null  null
Camshafts
The right cam choice can make the difference between a bike that performs well or fails to perform.
VThunder® cams provide the ultimate in arm-stretching, white knuckle power in both street and competitive
applications.
Most cam designers concentrate on getting the most power in a particular RPM range and disregard valve train
clatter and power band width. The designers at VThunder® pay particular attention to ramp design to keep our
cams as quiet as possible and lobe design to maintain as wide a power band as possible. VThunder® cams are
made from 6150 aircraft quality steel for ultimate durability and resistance to premature cam failure from metal
fatigue. We heat treat our cams to provide a case depth that allows for long term use under extreme loads.
With the aid of computer controlled machining centers, VThunder® cams are held to extremely
precise tolerances.
Backed by hundreds of hours on the Dyno and on-bike testing, our power proven cams provide added punch for
all levels of performance needs and riding styles for Evolution® and Shovel engines. Our cams provide the
longevity and valve train integrity you’ve come to expect with Harley Davidson®. Made in the U.S.A. with
American steel, our cams are packaged in full color high-strength boxes complete with detailed installation
instructions. VThunder® by COMP Cams® also offers a one-off special cam grind service.
Why do we do all these things? Easy . . . We want you to be happy with our products!!!
• Increased compression ratio or decreased camshaft duration will
increase cylinder pressure.
• Lift helps produce torque and horsepower.
• 30º or less overlap normally produces the best low-end power.
• The tighter the centerline; the shorter the power band.
1
Some products not legal for sale or use in California on pollution controlled vehicles
Evolution® Xtreme Energy™ Big Twin
Cams Specs
Gross
Part # Valve Lift
in.
/
ex.
Lobe Lift
Duration
@.053
in.
in.
/
ex.
/
ex.
Lobe
Base
Valve Timing Center
Lobe
Circle Tappet Lift Valve Lift
Open/Close Line Separation Radius
@TDC
@TDC
in.
/
ex.
in. / ex.
in. / ex.
in. / ex.
EVL-5000 .562 / .562
.346 / .346
230 / 230
17/33
41/9
98 / 106
102
.515”
.106” / .080” .172” / .130”
EVL-5005 .569 / .569
.350 / .350
236 / 236
18/38
42/14
100 / 104
102
.515”
.109” / .097” .177” / .158”
EVL-5010 .585 / .585
.360 / .360
244 / 244
22/42
48/16
100 / 106
103
.505”
.125” / .105” .203” / .171”
EVL-5015 .585 / .585
.360 / .360
252 / 252
26/46
52/20
100 / 106
103
.505”
.140” / .112” .228” / .182”
EVL-5020 .585 / .585
.360 / .360
260 / 260
28/52
56/24
102 / 106
104
.505”
.147” / .133” .239” / .216”
EVL-5025 .601 / .601
.370 / .370
268 / 272
32/56
64/28
102 / 108
105
.495”
.162” / .148” .263” / .240”
EVL-5000...
EVL-5005...
EVL-5010...
EVL-5015...
EVL-5020...
EVL-5025...
excellent low end and mid range power from idle to 5300 rpm. Great for two up riding or pulling a trailer
Power from 1500-5500rpm. Strong low end and mid range power for heavy bikes. Good on highway
Increased mid and upper end power for lighter bikes. Stock heads with spring change ok. 1800-5800 rpm
Great mid and upper end power in modified 80/88 in. Increased compression (9.5:1), pipes and carb work
88 in. and up, 10:1 compression, performance carb. / exhaust. Good power in light bike. Up to 6500 rpm
For serious power in 88 cu. in. and up, 10.5:1 compression, head work, performance exhaust and carb
Add NG for cam without gear (5020NG/5020SPNG)
Evolution® Xtreme Energy™ Big
Twin Cam Kits
Kit Part #’s
Includes
EVL-5000P-5025P
EVL-5000SP-5020SP
EVL-5001SP-5021SP
EVL-5025SP
EVL-5026SP
Includes cam, 7002R-KIT adjustable push rods and VT7006 Torrington bearing. (NG for no gear)
Includes cam, 9702-KIT spring kit, 7002R-KIT adjustable push rods and VT7006 Torrington bearing.
Includes cam, 9703-KIT spring kit, 7002R-KIT adjustable push rods and VT7006 Torrington bearing.
Includes cam, 9801-KIT spring kit, 7002R-KIT adjustable push rods and VT7006 Torrington bearing.
Includes cam, 9802-KIT spring kit, 7002R-KIT adjustable push rods and VT7006 Torrington bearing.
9702-KIT:
9703-KIT:
9801-KIT:
9802-KIT:
VT908 spring, 749 chromemoly retainer, 618 locks (10º super locks w/lash cap recess), 4784 spring seat
VT908 spring, 727 titanium retainer, 618 locks (10º super locks w/lash cap recess), 4784 spring seat
927 spring, 732 titanium retainer, 618 locks (10º super locks w/lash cap recess), 4770 spring seat
927 spring, 721LW titanium retainer, 618 locks (10º super locks w/lash cap recess), 4770 spring seat
Part #
O.D.
I.D.
[email protected]
Checking
Height
[email protected]
Open Height
Height
Coil Bind
Application
Good To
9702 / 9703-KIT
1.510"
.745"
184 @ 1.850"
422 @ 1.280"
1.080"
.675" lift
9801 / 9802-KIT
1.539"
.731”
221 @ 1.900"
514 @ 1.300"
1.175"
.665" lift
7002R-KIT: Fast Times .049 wall chromemoly adjustable pushrods
We also offer special grind EVO cams
2
Evolution® Big Twin Cams
With
Gear
Without
Gear
EVL-2000
EVL-2000NG
EVL-2015
EVL-3000
EVL-2015NG
EVL-3000NG
EVL-3010
EVL-3010NG
EVL-3020
EVL-3020NG
EVL-3030
EVL-3030NG
EVL-3040
EVL-3040NG
EVL-3050
EVL-3050NG
EVL-3060
EVL-3060NG
EVL-3070
EVL-3070NG
Description
hydraulic • bolt-in • excellent cam for stock replacements • good flat torque curve •
more power than stock • off idle to 4800
hydraulic • bolt-in • good low & mid-range power for fuel injected baggers
hydraulic • bolt-in • good low end torque for heavy bikes • two up riding • trailer
puller • off idle to 5500 rpm
hydraulic • bolt-in • 80 inch engines • good low end torque and mid-range in heavy
and light bikes • 1500 to 5800 rpm • excellent fuel mileage
hydraulic • bolt-in • 80 inch engines • strong mid-range and upper end power with
stock heads • 1800 to 6000 rpm
hydraulic • use 9702 / 9703-kit V-Thunder springs • 80-88 inch engines • more mid
and upper end power than EVL 3020 • works well with up to 10:1 compression
2000-6800 rpm
hydraulic • use 9702 / 9703-kit V-Thunder springs • split duration cam for light bikes
• 80-88 inch engines • more mid-range and upper end power than EVL-3030 •
2500-6500 rpm
hydraulic • use 9702 / 9703-kit V-Thunder springs • good performance cam on light
bikes • pulls hard at upper end • likes pipes, carburetor and 9:1 to 10:1 compression and up • 7000 rpm
hydraulic • 9702 / 9703-kit V-Thunder springs • hot street or strip cam • needs
carburetor, pipes and 10:1 compression • 88 inch engines and larger • 7000+ rpm
hydraulic • 9900-kit V-Thunder springs • serious cam for outstanding top-end power
• needs good heads, pipes & carburetor • power to 7500 rpm • 11:1 compression
and up • works best in 88 inch engines and larger
Evolution® Big Twin Cam Specs
Gross
Part # Valve Lift
in.
/
ex.
EVL-2000 .480 / .456
Lobe Lift
Duration
@.053
in.
in.
/
ex.
/
ex.
Lobe
Base
Valve Timing Center
Lobe
Circle Tappet Lift Valve Lift
Open/Close Line Separation Radius
@TDC
@TDC
in.
/
ex.
in. / ex.
in. / ex.
in. / ex.
.300 / .285
220 / 214
2/38 / 35/1
108 / 108
108
.530"
.059" / .049" .094" / .078"
EVL-2015 .500 / .500 .3125 / .3125
224 / 234
14/22 / 49/5
94 / 112
103
.530"
.092" / .069" .147" / .110"
EVL-3000 .500 / .500 .3125 / .3125
224 / 224
10/34 / 34/10
102 / 102
102
.530"
.080" / .080" .128" / .128"
EVL-3010 .500 / .500 .3125 / .3125
234 / 234
15/39 / 39/15
102 / 102
102
.530"
.096" / .096" .154" / .154"
EVL-3020 .500 / .500 .3125 / .3125
240 / 240
18/42 / 42/18
102 / 102
102
.530"
.106" / .106" .170" / .170"
EVL-3030 .530 / .530 .3313 / .3313
240 / 240
16/44 / 44/16
104 / 104
104
.525"
.099" / .099" .158" / .158"
EVL-3040 .510 / .510 .3188 / .3188
242 / 252
17/45 / 50/22
104 / 104
104
.528"
.101" / .117" .162" / .187"
EVL-3050 .510 / .510 .3188 / .3188
252 / 252
20/52 / 52/20
106 / 106
106
.530"
.111" / .112" .180" / .182"
EVL-3060 .585 / .585 .3625 / .3625
260 / 270
26/54 / 59/31
104 / 104
104
.515"
.131" / .145" .213" / .236"
EVL-3070 .608 / .608
270 / 274
29/61 / 63/31
106 / 106
106
.508"
.144" / .149" .230" / .238"
.380 / .380
VT7006...
EVO Torrington Camshaft Bearing
Add NG for cam without gear. (EVL-3030NG)
3
Evolution® Big Twin Cam Kits
The EVL-3000 thru EVL-3020 will work as a bolt in cam with your stock springs, but if your stock springs are
old or well used, new springs will insure the performance the cam is designed to give.
Kit Part #’s
Includes
EVL-3000P, EVL-3010P
AND EVL-3020P KIT
Includes cam and 7002R-KIT pushrods and VT7006 Torrington camshaft bearing.
The EVL-3000SP through EVL-3020SP kits use 9700-KIT, EVL- 3001SP through EVL-3021SP uses 9701-KIT.
Kit Part #’s
9700-KIT:
9701-KIT:
Includes
VT977 spring, 740 chromemoly retainer, 618 locks (10º super locks w/lash cap recess),
4770 spring seat
VT977 spring, 730 titanium retainer, 618 locks (10º super locks w/lash cap recess), 4770
spring seat
The EVL-3030SP through EVL-3060SP kits use 9702-KIT, EVL- 3031SP through EVL-3061SP uses 9703-KIT.
Kit Part #’s
9702-KIT:
9703-KIT:
Includes
VT908 spring, 749 chromemoly retainer, 618 locks(10º super locks w/lash cap recess),
4784 spring seat
VT908 spring, 727 titanium retainer, 618 locks(10º super locks w/lash cap recess), 4784
spring seat
EVL-3070SP kit comes with the 9801-KIT spring kit.
Kit Part #’s
9801-KIT:
9802-KIT:
Part #
Includes
927 spring, 732 titanium retainer, 618 locks (10º super locks w/lash cap recess), 4770
spring seat
927 spring, 721 lightweight titanium retainer, 618 locks, 4770 spring seat
O.D.
I.D.
[email protected]
Checking
Height
[email protected]
Open Height
Height
Coil Bind
Application
Good To
9700 / 9701-KIT
1.460"
.700"
160 @ 1.850"
440 @ 1.280"
1.200"
.600" lift
9702 / 9703-KIT
1.510"
.745"
184 @ 1.850"
422 @ 1.280"
1.080"
.675" lift
9801 / 9802-KIT
1.539"
.731”
221 @ 1.900"
514 @ 1.300"
1.175"
.665" lift
4
Shovelhead Cams
With
Gear
Description
SHV-4000
SHV-4001
SHV-4010
1978-84 engines • hydraulic • bolt-in • strong low end • good mid-range
1970-77 engines • hydraulic • bolt-in • strong low end • good mid-range
1978-84 engines • hydraulic • valve springs required • more lift than SHV-4000 & SHV-4001 • more
low end and mid-range
1970-77 engines • hydraulic • valve springs required • more lift than SHV-4000 & SHV-4001 • more low
end and mid-range
1978-84 engines • hydraulic • valve springs required • increased mid-range over SHV-4010 & SHV-4011
• good roll-on power
1970-77 engines • hydraulic • valve springs required • increased mid-range over SHV-4010 & SHV-4011
• good roll-on power
1978-84 engines • hydraulic • hot street cam for small strokers • 74-80 inch engines • good power to
6000 rpm • likes carb, pipes and increased compression • valve springs required
1970-77 engines • hydraulic • hot street cam for small strokers • 74-80 inch engines • good power to
6000 rpm • likes carb, pipes and increased compression • valve springs required
1978-84 engines • hydraulic • valve springs required • good split duration cam for 74-80 inch engines
with carburetor and pipes • longer exhaust help cool engine • power to 5800 rpm
1970-77 engines • hydraulic • valve springs required • good split duration cam for 74-80 inch engines
with carburetor and pipes • longer exhaust help cool engine • power to 5800 rpm
1978-84 engines • hydraulic • very hot cam for street or drag • likes big engines • carburetor, pipes
and increased compression a must • 84 to 96 inch strokers • 7000 rpm
1970-77engines • hydraulic • very hot cam for street or drag • likes big engines • carburetor, pipes
and increased compression a must • 84 to 96 inch strokers • 7000 rpm
SHV-4011
SHV-4020
SHV-4021
SHV-4030
SHV-4031
SHV-4040
SHV-4041
SHV-4050
SHV-4051
Shovelhead Cams Specs
Gross
Part # Valve Lift
in.
/
ex.
Lobe Lift
Duration
@.053
in.
in.
/
ex.
/
ex.
Lobe
Base
Valve Timing Center
Lobe
Circle Tappet Lift Valve Lift
Open/Close Line Separation Radius
@TDC
@TDC
in.
/
ex.
in. / ex.
in. / ex.
in. / ex.
SHV-4000 .450 / .450
.316 / .316
236 / 236
14/42 / 42/14
104 / 104
104
.515"
.093" / .093" .133" / .133"
SHV-4001 .450 / .450
.316 / .316
236 / 236
14/42 / 42/14
104 / 104
104
.515"
.093" / .093" .133" / .133"
SHV-4010 .485 / .485
.340 / .340
236 / 236
14/42 / 42/14
104 / 104
104
.470"
.093" / .093" .133" / .133"
SHV-4011 .485 / .485
.340 / .340
236 / 236
14/42 / 42/14
104 / 104
104
.470"
.093" / .093" .133" / .133"
SHV-4020 .485 / .485
.340 / .340
242 / 242
17/45 / 45/17
104 / 104
104
.470"
.103" / .103" .147" / .147"
SHV-4021 .485 / .485
.340 / .340
242 / 242
17/45 / 45/17
104 / 104
104
.470"
.103" / .103" .147" / .147"
SHV-4030 .485 / .485
.340 / .340
252 / 252
22/50 / 50/22
104 / 104
104
.470"
.120" / .120" .171" / .171"
SHV-4031 .485 / .485
.340 / .340
252 / 252
22/50 / 50/22
104 / 104
104
.470"
.120" / .120" .171" / .171"
SHV-4040 .485 / .485
.340 / .340
242 / 252
17/45 / 50/22
104 / 104
104
.470"
.103" / .120" .147" / .171"
SHV-4041 .485 / .485
.340 / .340
242 / 252
17/45 / 50/22
104 / 104
104
.470"
.103" / .120" .147" / .171"
SHV-4050 .550 / .550
.385 / .385
260 / 270
24/56 / 61/29
106 / 106
106
.470"
.128" / .145" .182" / .207"
SHV-4051 .550 / .550
.385 / .385
260 / 270
24/56 / 61/29
106 / 106
106
.470"
.128" / .145" .182" / .207"
Late Model (78-84) has groove in Cam Gear.
Early Model (70-77) does not have groove in Gear.
5
80-81 Engines are restricted to .430 lift due to the valve guides.
Shovelhead Rocker Ratio - 1.43.
FAST TIMES™ Pushrods
So, what does it matter what pushrod I use? I mean, a pushrod is a
pushrod . . . right? WRONG!! The quality & construction of a pushrod
can mean the difference between valve train stability or instability due
to uncontrolled vibration (pushrod resonance). When the configuration
and material properties of the pushrod are increased for the better, so
will the performance of that pushrod.
Because each and every VThunder® pushrod is manufactured from .049"
wall, 4130 chromemoly steel and precision machined to exacting tolerances,
they provide the ultimate in reliability and performance, with applications for EVOs, Shovels,
and Panheads. Our “Fast Times™” pushrods feature an innovative adjustment system which makes
installation a snap on EVO Big Twins by eliminating the necessity to remove the rocker boxes. The adjuster portion of the
pushrod features 4140 high strength steel, with an induction hardened tip for severe service applications. Made in the United States.
Pushrods
VThunder
Year
Model
Engine
Panhead–1948-1965 Big Twin
1948-1965
Big Twins
Pan
9002S-KIT
Panhead–Stroker Pushrods*
1948-1965
Big Twins
Pan
8002-KIT
Shovelhead–1966-1984 Big Twin
1966-1984
Big Twins
Shovel
8002S-KIT
Shovelhead–Stroker Pushrods*
1966-1984
Big Twins
Shovel
7002-KIT
Evolution–1984-up Big Twin
1984-present
Big Twins
Evo
7002S-KIT
Evolution–Stroker Pushrods*
1984-present
Big Twins
Evo
9002-KIT
Application
*Stoker Pushrods are .250” longer than standard pushrods
7013-KIT
Stock Setup
1999-present
Twin Cam
TC88
7002R-KIT
Evolution–Fast Times w/stock HD blocks
1984-present
Big Twins
Evo
Build-Your-Own Stroker Pushrod Kits
7003-KIT
.049 wall thickness -for tall cylinders
1984-present
Big Twins
Evo
7004-KIT
.080 wall thickness -for tall cylinders
1984-present
Big Twins
Evo
VThunder® push rods are 24 threads per inch. With 24 threads per inch one flat equals .0069”. One turn (6 flats) equals .0417”.
You must adjust lifters to the lifter manufacturers specifications.
• When installing Fast Times™ pushrods with stock style lifters, turn
the adjuster out 3 turns (18 flats) from zero lash.
Build-Your-Own
Our new 7003-KIT and 7004-KIT are specially designed for stroker motors with tall cylinders. They
both feature 7/16” diameter tubing. The 7003-KIT has a .049 wall thickness and features press-in
ends. The 7004-KIT has a slightly thicker .080 wall designed for fuel motors and features screw-in
ends. Just measure the length you need, cut the tubing, and press in the end. Faster, easier, precision
pushrods built on a history of winning performance and made in the United States. The 7004-KIT,
with the threads right in the tube, works great in Stroker Motors where pushrod tube cover clearance
is a problem.
6
Springs, Retainers & Locks
Harley Davidson®’s unique V-Twin design puts a tremendous amount of
stress on the valve train. With the increased pressures, valve spring
consistency and reliability are at a premium. At VThunder®, we’ve
eliminated the worry.
In order to deal with these excessive demands, VThunder®
springs, retainers and locks are made from the highest grade
materials, such as Chromemoly and Titanium. Heat treated to
the highest industry standards, our valve train components
are tested at levels that can’t be duplicated on the street or track.
Our torture testing ensures not only consistent quality, but
unmatched performance as well.
Our spring kits incorporate an interference double spring design with a
damper. The damper keeps the inner and outer spring coils from
locking together, while controlling power-robbing harmonics in the spring.
VALVE LOCKS
PART #
VT612-4
DESCRIPTION
Super Locks w/lash cap recess
YEAR
1948-1984
MODEL
Big Twins
ENGINE
LOCK ANGLE VALVE STEM SIZE
Pan/Shovel
10°
3/8"
VT616-4
Super Locks +.050 Inst. Hgt.
w/o recess for lash caps
1957-1985
XL Exhaust
Sportster
10°
3/8"
VT617-4
Super Locks w/o lash cap recess
1984-Present
Big Twins/XL Exhaust
1957-1985 XL Intake
Evo BT/Evo
Iron Sportster
10°
5/16"
VT618-4
Super Locks w/lash cap recess
1984-Present
Big Twins/XL Exhaust
1957-1985 XL Intake
Evo BT/Evo
Iron Sportster
10°
10°
5/16"
5/16"
PART #
DESCRIPTION
YEAR
MODEL
ENGINE
LOCK
ANGLE
VT730-4
Titanium, double springs
1984-Present
Big Twins
Evo
10°
All
1.437-1.500"
VT732-4
Titanium, double springs
1984-Present
Big Twins
Evo
10°
All
1.500-1.550"
VT740-4
Chromemoly
1984-Present
Big Twins
Evo
10°
All
1.437-1.500"
VT741-4
Chromemoly
1984-Present
Big Twins
Evo
10°
All
1.500-1.550"
VALVE SPRING RETAINERS
SPRING SEATS
ENGINE
THICKNESS
PART #
DESCRIPTION
YEAR
MODEL
VT4770-1
Spring Seat
1984-Present
Big Twins
Evo
VT4770-4 Spring Seat(set of 4) 1984-Present
Big Twins
Evo
PART #
VT927
7
DESCRIPTION
1.539 Hi-Tech™ Endurance Valve Spring
I.D
.O.D.
.060"
.585"
.060"
.585"
VALVE
VALVE SPRING
STEM SIZE
DIAMETER
1.500"
FITS
I.D.
NA
SPRING
I.D.
.690"
1.500"
NA
.690"
VALVE SPRINGS
SEAT LOAD
OPEN LOAD
COIL BIND
RATE (lbs/in)
.731”
221 @ 1.900
514 @ 1.300
1.175”
488
I.D.
VT972
1.460 Outer w/Damper
1.060"
125 @ 1.800
275 @1.300
1.150"
300
VT973
.970 Inner Spring
.700"
45 @1.750
120 @ 1.200
1.075"
136
VT954
1.540 2 Spring Assembly
.725"
195 @ 1.900
515 @ 1.250
1.175"
492
VT999
1.550 H-11 Spring Assembly
.710"
230 @ 1.875
700 @ 1.200
1.100"
696
VT908
1.51
.745"
184 @ 1.85
422 @1.280
1.080"
425
Spring Kits
VThunder®’s high performance valve spring kits are engineered for maximum performance in severe service applications such as high
compression, big inch motors.
Whether you’re cruisin’ on the streets or makin’ a pass down the track, our spring assemblies will last longer, fight harder and lift
better. Our spring kits come in a variety of ranges and include locks, retainers and spring seats that are custom fit to provide positive
location to prevent the spring from ‘dancing’ around on the cylinder head which can create harmful harmonics and excessive wear.
We also feature a full line of springs and components for race applications that are available to professional racers direct through our
‘Racers Only’ program. Bottom line . . . you wanna’ go fast? Use VThunder® Springs and components!!!!
Don’t believe us? Ask world record holder Pro Stock racers Rob Korn and speed wizard Craig Walters, or Lee Clemens of Departure
Bike Works Racing what springs they chose to keep their bikes winning and setting records!!!
PART #
APPLICATION
9700-KIT
9701-KIT
9702-KIT
9703-KIT
9800-KIT
9801-KIT
9802-KIT
9900-KIT
TC88
Evo Big Twin
Sportster EVO
TC88
Evo Big Twin
Sportster EVO
TC88
Evo Big Twin
Sportster EVO
TC88
Evo Big Twin
Sportster EVO
TC88
Evo Big Twin
Sportster EVO
TC88
Evo Big Twin
Sportster EVO
TC88
Evo Big Twin
Sportster EVO
TC88
Evo Big Twin
Sportster EVO
DESCRIPTION
YEAR
O.D
.I.D.
PRESSURE
@ CHECKING
HEIGHT
PRESSURE COIL RETAINERS INDIVIDUAL
@ OPEN
BIND
SPRING
HEIGHT HEIGHT
PART #
KITS INCLUDE SPRING LOCKS, RETAINERS AND LOWER SEATS
Good street &
performance spring
1984-up 1.460" .700" Lbs.-160/
Lbs.-440/
to .600" lift
In.-1.850
In.-1.250"
Good street &
performance spring
1984-up 1.460" .700" Lbs.-160/
Lbs.-440/
to .600" lift
In.-1.850
In.-1.250"
Super springs. Excellent
street & performance 1984-up 1.510" .745" Lbs.-184/
Lbs.-422/
spring up to .675" lift
In.-1.850
In.-1.280"
Super springs. Excellent
street & performance 1984-up 1.510" .745" Lbs.-184/
Lbs.-422/
spring up to .675" lift
In.-1.850
In.-1.280"
For race applications
Lbs.-195/
Lbs.-515/
up to .675" lift
1984-up 1.540 .725"
In.-1.900
In.-1.250"
1.200" Chromemoly
VT972
VT973
1.200"
VT972
VT973
Titanium
1.080" Chromemoly
VT908
.080"
Titanium
VT908
1.175"
Titanium
VT954
Performance spring up
to .640” lift
1984-up 1.550
.585”
Lbs.-233/
In.-1.875
Lbs.-545/
In.-1.235
1.175”
Titanium
VT927
Performance spring up
to .665” lift
1984-up 1.550
.585”
Lbs.-233/
In.-1.875
Lbs.-545/
In.-1.235
1.175”
Titanium
VT927
1984-up 1.550" .710"
Lbs.-230/
In.-1.875
Lbs.-700/
In.-1.200"
1.100"
Titanium
VT999
For race applications
up to .700" lift
Performance Hydraulic Roller Lifters
VThunder® by COMP Cams®, the leader in valve train technology, introduces their new replacement
Evolution® Big Twin hydraulic roller lifter to its line of V-Twin aftermarket products. Our new lifter
features a rigid nodular cast iron body with a 52100 bearing, axle and wheel assembly for strength.
VThunder®’s lifter utilizes an advanced ultra-high flow metering system which allows more oil
movement through the engine to aid in cooling. Each lifter is precision I.D. Ground and matched
with a Graded piston, and features a high performance retaining ring.
Part #’s
Description
7390-1
7390-4
Performance replacement hydr. lifter
Performance replacement hydr. lifter
850-1
High Energy® hydr. lifter
Year
Applications
Engine
1984-1999
1984-1999
Big Twin 86-90 XL
Big Twin
EVO
EVO
1999-present Twin Cam, Buell® 2000-pres.
Sportster® 2000-pres.
TC88
8
This blend of technology and precision manufacturing prevents improper bleed down that is often experienced with other so-called
“performance” lifters. Our race engineered Velva Touch™ lifters have become the standard of the industry through the use of strict
quality control, precision manufacturing, and the highest grade materials available.
Lifter Kits
VThunder
®
Application
Year
Model
Engine
Big Twins
Big Twins
Big Twins
Big Twins
Big Twins
Big Twins
Evo
Evo
Shovel
Shovel
Pan
Pan
Big Twins
Big Twins
Big Twins
Big Twins
Big Twins
Big Twins
Evo
Evo
Shovel
Shovel
Pan
Pan
KITS WITH CHROME LIFTER BLOCKS
7500-KIT
7600-KIT
8500-KIT
8600-KIT
9400-KIT
9500-KIT
7000-KIT
7100-KIT
8000-KIT
8100-KIT
9000-KIT
9100-KIT
Evolution–standard pushrods
1984-Present
Evolution–Stroker pushrods*
1984-Present
Shovelhead–standard pushrods
1966-1984
Shovelhead–Stroker pushrods*
1966-1984
Panhead–Stroker pushrods*
1948-1965
Panhead–standard pushrods
1948-1965
KITS WITH BLACK LIFTER BLOCKS
Evolution–standard pushrods
1984-Present
Evolution–Stroker pushrods
1984-Present
Shovelhead–standard pushrods
1966-1984
Shovelhead–Stroker pushrods
1966-1984
Panhead–standard pushrods
1948-1965
Panhead–Stroker pushrods
1948-1965
*Stroker pushrods are .250" longer than standard pushrods.
• Check to make sure the screws that hold the lifters in the block
are tight. Do not over tighten or you could distort the lifter bores.
• Trial fit the lifters in the engine, make sure the lifters are free in the bores
after you tighten them down. If any of the lifters tighten up in the bores after you tighten them
down, remove the nose cone and check to see if the blocks are touching the engine crankcase.
If they are, remove the lifter blocks and clearance them with a die grinder.
• For street bikes, adjust the pushrod out 1 1/2 turns from zero lash. If you have a race bike,
adjust the front pushrods 7 wrench flats and the rear 4 wrench flats.
Velva Touch™ Lifters
Velva Touch™ Hydraulic Lifter Kits are the world’s only “engineered from scratch”
lifter assembly and provide the ultimate (bar none) in total performance and
precision for your street driven Harley®.
VThunder®’s patented Velva Touch™ lifter blocks replace and far
outperform the stock aluminum lifter blocks; our lifter blocks are
manufactured with a tough cast iron alloy to closely match expansion
rates of our lightweight steel lifters so they can maintain precision
tolerances even when the engine is hot. A patented oiling system provides each
lifter with its own independent supply of oil to insure proper lubrication and
enhanced tappet operation at low or high RPM ranges.
* Only EVO Kits come with Pushrod Covers.
9
7500-KIT
Shown
Hy-Rev™ Hydraulic LIfter
All of the lifters components are produced on state-of-the-art computer controlled machinery which holds the O.D. size, straightness
and roundness tolerances to .0003", for the precise fit demanded of today’s high performance engines. Proudly made in the United
States, each lifter must pass a stringent quality control test to ensure proper manufacture and function.
HY-REV™ Lifters
VThunder®
Description
Year
Model
Engine
™
7410-1
HY-REV Anti Pump up
Hydraulic Lifter
1991-99
SPORTSTER
EVO
7410-4
HY-REV™ Anti Pump up
Hydraulic Lifters - Set of Four
1991-99
SPORTSTER
EVO
1999-Present
TWIN CAM
Buell® 2000-pres.
Sportster® 2000-pres.
TC88
875-1
™
HY-REV Hydraulic lifter
• When installing any hydraulic lifter, always clean the tappet screen
which filters the oil to the filters.
• After installing and adjusting the pushrods, always let the front lifters
bleed down before rotating the engine to install the rear lifter blocks.
This HyperFyre™ ignition is programmable by switch or with our proprietary ProFire™
software. It also features an LED for static timing, a two-step rev limit RPM activated
RPM switch coupled to an automatic timing retard. Hidden inside the gear cover, the
HyperFyre™ is housed in billet aluminum that is guaranteed to withstand the high
temperatures found in the cover. The wiring harness is optimally located on the
face of the HyperFyre™ for easy installation. The HyperFyre™ is manufactured in
Tennessee, U.S.A. with the highest heat and vibration rated, premium quality
Mil-spec components available. One unit operates in either single or dual fire
modes with the stock trigger wheel; just remove the stock sensor, route the high
temperature silicone jacketed wiring harness through the bottom of the gear
cover, and bolt it down with the stock standoffs. The HyperFyre™ Ignition’s
components allow for increased amperage to the spark plugs and its micro
circuitry makes it only 1/2" thick for ultra easy installation.
Part #’s
Description
Year
VTI2010
HyperFyre™ Digital Covert Ignition
1970-Present
Applications
Big Twin & XL Model 45° V-Twins
10
Are you tired of the limitations that manufacturers place on the amount of adjustability and tunability you get in so-called “high tech” ignitions? Are you waiting for
an ignition that is bolt-on easy and fully adjustable for street tuning, but totally
programmable for really serious tuners?
Built right here in the good old United States of America, our new super
performance Ignition Controller features high-energy, accurate spark
timing, the industry’s easiest installation and unmatched programming
capability. This combination of simple sophistication will meet the needs of
racers and professional engine builders, as well as weekend enthusiasts who
wish to try their hand at a little “home tweaking”. The VThunder® Ignition Controller is
fully potted to protect internal components from weather hazards, vibration and heat.
Installation is virtually “stock replacement” easy with no need even to remove the cone
cover. Fourteen (14) factory programmed baseline curves will cover most popular
engine combinations, but for the more progressive tuner, our unique “switch programming” method allows access to advanced features such as dwell control and nitrous
retard for use with the RPM switch feature. The optional Programming Interface Module
and ProFire™ Software disk allows unlimited access to all integral computer settings for
complete programmability.
VThunder®
Description
Year
Model
Engine
*VTI2000A
Ignition Controller
7 pin
1995-earlier Softail, Dyna, FXR, FX (w/conversion harness) Shovel, Evo, Sportster
1993-earlier
XL (except 1994-later FLT & XL models)
VTI2000B
Ignition Controller
8 pin
1996-present
1994-present
*VTI2001A
Power adapter (7-pin connector)
fits all VTI2000A applications
Softail, Dyna
FLT (except F.I.), XL
VTI2001B
Power adapter (8-pin connector)
fits all VTI2000B applications
VTPM2100
PC Programming Interface
Module w/ProFire® software
For use with VTI2000A/B
Ignition Controllers
VTE2200
RPM switch harness
For use with VTI2000 A or B
Evo
*For 1979 and earlier models use pickup #32402-80A and rotar #32402-83. For 1991 and earlier models use OE harness #32408-90.
• When installing the Controller™ Ignition Computer, be sure that you
have a good ground to the ignition and the battery, as well as an
adequately charged battery. A poor ground or undercharged battery
are common causes of ignition problems.
• Solid core (copper/stainless) plug wires tend to produce a high amount of RFI (Radio Frequency
Interface), which can disrupt the operation of some electronic ignitions. For those types of
ignitions, it is best to use a suppression (graphite) core type plug wire.
• Both ‘A’ & ‘B’ switches should be on ‘0’ for static timing.
11
Velva Ride™ Vibration Control Systems
Harley® riders love the loping, pulsing idle that the Big Twin power plant produces. But these same uneven power pulses also produce
excessive vibration that can contribute to significant rider fatigue during long rides. That is the precise reason to install our total Velva
Ride™ Vibration Control System which dramatically reduces transmitted engine vibration to the rider by up to 50%. Now you can have
the sound and torque you want without experiencing that numbing feeling at the end of a long day’s ride.
Velva Ride™ Evolution® Motor Mount
The best cure for the Big Twin’s transmitted vibration problem was rubber
isolating the engine from the frame. We took this idea to the next logical step by
using a specially designed urethane motor mount with matching compression
and rebound sides to quell vibration using modern plastics technology. Urethane
has a much better “memory” than does ordinary rubber, and will out-last and
out-dampen the stock rubber mount by a substantial margin.
The end result? Now you can enjoy that famous Milwaukee rumble with up to a 20% reduction in
transmitted vibration. The Velva Ride™ Motor Mount is now available in a highly polished billet aluminum, or
the original black powder coat.
VThunder®
Description
Year
Model
Applications
9200-KIT
9200P-KIT
Front Motor Mount (Black)
Front Motor Mount (Polished)
1980-present
1980-present
FXR/FLT
FXR/FLT
Shovel/Evo
Shovel/Evo
Velva Ride™ Engine Stabilizers
Transmitted engine vibration is the enemy of every long weekend ride. With this in mind, our
engineers attacked the problem by developing a patented stabilizer that emulates a miniature shock
absorber to successfully fight the transmission of vibration.
The stainless steel body contains a plunger encased in specially formulated urethane that
significantly outperforms the stock stabilizers.
When properly installed on rubber mount models, the urethane plunger and rod ends isolate the
engine from the frame by cancellation of metal to metal contact. Each pair comes complete with
rod ends and are ready to install on most rubber mount frames from 1980 to present. They are
available single or in pairs, and with standard finish or fully polished stainless body and rod ends.
VThunder® #
Description
9600P-KIT
™
Year
Model
Engine
Velva Ride Polished
Engine Stabilizer (pair)
1980-2000
FXR/FLT
Shovel/Evo
Twin Cam
9600P-1
Velva Ride™ Polished
Engine Stabilizer (single)
1980-2000
FXR/FLT
Shovel/Evo
Twin Cam
9600-KIT
Velva Ride™
Engine Stabilizer (pair)
1980-2000
FXR/FLT
Shovel/Evo
Twin Cam
9600-1
Velva Ride™
Engine Stabilizer (single)
1980-2000
FXR/FLT
Shovel/Evo
Twin Cam
• When installing the Velva Ride™ engine stabilizers, always set the
Velva Ride™ stabilizers to the same length as the stock stabilizers.
If you think your engine is out of alignment, check your Harley®
manual for the proper way to align your engine.
12
Torsional Vibration Absorber
Due to their mechanical design, all internal combustion engines emit torsional crankshaft
vibrations. Harley Davidsons® are no exception. These twisting vibrations are caused by
slight increases and decreases in engine speed during the power and compression strokes.
This twisting can be controlled either by dissipating the energy, or by absorbing the energy
that causes the crankshaft to twist.
The VTVA5 provides torsional control in the form of internal rollers designed to automatically
offset the twisting forces, thereby eliminating the vibration. The VTVA5 is a CNC machined,
high-quality mechanism that simply bolts in place of the OEM compensator and crankshaft torsional vibration
absorber. Made in the United States.
Torsional Vibration Absorber
®
VThunder #
VTVA5
Description
Fits all 1983 - up Harley Davidson® Big Twin Rigid Mount
Engines (Including all Softail® models). It can also be
used on 1970-82 if a late primary sprocket (OE#40275-83A)
is used. Fits all 1991 - up Dyna models. The VTVA5
will not fit Sportster or FXR models.
Evolution® TC88 Roller Rocker Arms
VThunder® by COMP® announces the newest addition to its impressive list of innovative high
performance Harley® components, EVO Roller Rocker Arms.
VThunder®’s EVO Roller Rocker Arms are designed to reduce friction and valve wear.
Constructed of 4130 Chromemoly steel. They can be used with a stock camshaft, but when
combined with a high performance camshaft, they are a must to maximize your motorcycle’s
power potential.
VT7008-KIT
Evo Rocker Arm KIT
Much Needed Tools & Accessories
Harley® Head Plate
If you work on Harley Davidson® cylinder heads, you need this tool. Our new Harley Head Plate works with Evolution™,
Sportster™ and Shovel Head™ styles to act as a foundation when doing any cylinder head work. Once the head is
attached to the anodized aluminum plate, you can use ordinary peg head holders to position the head for porting &
polishing, guide work, grinding seats and checking stem heights. Our plate is also perfect for mounting on a seat & guide
machine or bolting to a resurfacer.
VT351415
Harley Head Plate
Peg-Style Head Holders
Our Peg-Style Head Holders are a great low cost way to suspend your cylinder heads above your workbench when performing port
and polish work. The tapered pins slide into the cylinder head bolt holes so you can hold the head right-side up or upside down.
POW351410
13
Peg-Style Head Holders (pr.)
Pro Valve Lapping Tool
Tired of the prehistoric valve lapping ritual? There is finally an answer to your prayers. This patented valve lapping tool uses a vacuum
generating piston to create a suction that will not slip off the valve. It includes three interchangeable suction cups, which allows use on
virtually any valve size. It also features a non-slip foam rubber grip that improves grip and comfort over the traditional "wooden stick" designs.
The tool is made from machined aluminum, which will provide durability and value for years to come.
POW351051
POW351069
Pro Valve Lapping Tool
Replacement Suction Cup Set
Spark Plug Hole Thread Chaser
A stripped spark plug hole is not a fun thing to fix. Avoid this trouble by using our Spark Plug Hole Thread Chaser to renew
damaged threads and allow firm seating of plugs. Our long 13/16" hex design prevents wobble while the neoprene ring holds
the heat-treated chaser snugly in your socket. Our tool is double ended to fit both 14mm & 18mm threads.
POW351690
14mm & 18mm Thread Chaser
Valve Seal Installer
Our CNC machined aluminum Valve Seal Installer makes installing PC seals a breeze. This tool works with .500” and .531” PC
seals and prevents seal distortion or gouging during installation. Anodized for durability.
5334
Valve Seal Installer
Mini Valve Spring Tester
Our hydraulic Mini Spring Tester is designed to be a portable and low cost alternative to a bench top style spring tester. Our
0-1000lb tester is scaled off in 20lb increments and includes a rubber gauge protector and a recalibration feature. The hex
design body can be placed in a vise, used with an arbor press, or with the addition of a flange, used in a drill press.
5314
5315
5316
0-1000 lb. Mini Valve Spring Tester
Drill Press Flange
Calibrated Test Spring
Arbors & Seat/Guide Cutters
Most high performance engines require larger than stock diameter valve springs. Our Spring Seat Cutters allow you
to machine the spring seats using an ordinary hand drill. We even offer seat cutters to accommodate the spring seat
cups that are so widely used today (Note: all seat cutters cut to .630" inside diameter). Our Valve Guide Cutters are
designed to shorten the valve guide boss for high lift cams, and also reduce the outside diameter to accept triple
springs and/or aftermarket valve seals. Each tool utilizes our Interchangeable Arbors, which are sold separately, so
order the one that matches your valve stem diameter.
4719
4720
4722
4727
4725
Spring Seat Cutter 1.550" O.D.
Spring Seat Cutter 1.580" O.D. (For use with cup)
Spring Seat Cutter 1.680" O.D. (For use with cup)
Valve Guide Cutter .446" (For triple springs)
Valve Guide Cutter .485" (For triple springs)
4726
4728
4730
4732
4734
Valve Guide Cutter .530" (For standard teflon seals)
Valve Guide Cutter .625" (For stock diameter seals)
Arbor/Pilot for Cutters - 5/16" diameter
Arbor/Pilot for Cutters - 11/32" diameter
Arbor/Pilot for Cutters - 3/8" diameter
V-Twin Performance Tuners Handbooks
Three excellent technical books by Denny Dennish covering high performance parts to engine design and building,
tuning tips to performance theories, and power curve analysis to track side tuning. If you are serious about
building or tuning for power, these books are a must.
VT901055
VT901060
VT901065
Big Twin High-Performance Guide
V-Twin Tuner’s Handbook, Volume One
V-Twin Tuner’s Handbook, Volume Two
14
Pro Valve Lock Removal and Installation Tool
Don’t risk your fingers when removing or installing valve locks anymore. Our new magnetic tool is definitely the best way to perform this
delicate task. To install locks; compress valve spring, place valve locks on magnetic stem, push body of tool over the locks and position them on
the valve stem, release valve spring. To remove locks; use the magnetic stem to pluck off the valve locks once the spring is compressed. Several
sizes available to cover most automotive and motorcycle applications.
5307 Pro Valve Lock Tool - 5mm, 5.5mm, and 6mm Locks
5308 Pro Valve Lock Tool - 7mm, 8mm, and 5/16” Locks
5309 Pro Valve Lock Tool - 11/32” Locks
5310 Pro Valve Lock Tool - 3/8” Locks
Valve Spring Height Micrometers
This is by far the quickest, easiest, and most accurate way to measure valve spring installed height. Our height mics install
just like a valve spring then the tool is expanded until it has fully seated the valve, locks, and retainer. This simulated installation is what allows ultra precise readings. The tool is then read like a micrometer and is accurate to .001”.
4928
4929
1.400” to 1.800” Range Height Micrometer
1.600” to 2.200” Range Height Micrometer
VThunder®Racing T-Shirt
Vthunder® 100% preshrunk cotton T-shirts have a full color VThunder® logo on the back and a smaller logo on the chest. They are
the perfect racing T-shirt for any occasion. The shirts are available in... L, XL, XXL, & XXXL.
VT106
Vthunder® Racing T-Shirt
Research & Development
VThunder® by COMP Cams’® attention to the future has set it apart in the motorcycle aftermarket industry. At VThunder® we don’t wait on
technology, we define it. Our R&D team provides unmatched ability in designing the world’s finest camshafts and valve train
components. That experience, coupled with the latest computer-aided technology for carrying out every phase of the design process,
provides the ability to produce a product that few, if any, can match.
The following are just a few of our ingredients for success which ensures YOUR success.
• A one-of-a-kind computer based cam profile organizer, custom made to our specifications, which is used for cam design as well as
measuring and recording all data from each and every performance cam and stores the information to a database by serial number.
• Two independent valve motion analyzers. One is OPTRON-based, while the other uses a laser transducer to sense valve motion.
• A spin fixture for valve train component durability and over stress testing capable of maintaining speeds up to 12,000 RPM.
• Three fully functional CAD stations, each equipped with the latest in design and modeling software.
• A complete Superflow Dynomometer, with baseline test engines.
• A computer driven camshaft master maker that cuts what was previously a four day process to make a camshaft into a two
hour process.
In addition to these items, we have a complete machine shop on premises to do anything from tooling and prototype fabrication to all
aspects of engine rebuilding, as well as a fully equipped dimensional/material analysis laboratory for measuring any feature of our parts that
we desire. All this technology gives us the ability to provide our customers with “Products That Have Unmatched Quality & Unbelievable
Performance.”
Degreeing a Cam
Without a degree wheel:
If the engine is in the chassis, use a stand to get the rear wheel off the ground. Using a dial indicator to get a measurement at the lifter, start
with the intake lifter. Put the transmission in high gear then rotate the rear wheel forward until the intake lifter is at the lowest point (heel of
the cam), and set the indicator to zero. Continue to rotate the rear wheel in the same direction and watch for the TDC (Top Dead Center) mark
to center itself in the timing inspection hole. Take note of the indicator reading at this point. Now, rotate the rear wheel in the opposite
direction back to the zero reading on the indicator. At this point, double check that the intake lifter is again at its lowest point. The exhaust
lifter is done in the same manner, however start by rotating the rear wheel backwards to get the lowest point of the lifter (0˚ indicator
reading). Then continue in the same direction until you get the TDC mark centered in the timing inspection hole. Note the indicator reading
and then rotate the rear wheel forward until you again see the exhaust lifter at its lowest point and a ‘0’ indicator reading. The readings for
the intake and exhaust should coincide with the manufacturers cam spec card supplied with your cam.
15
With a degree wheel:
Install the degree wheel and pointer on the sprocket shaft, being sure that the degree wheel will not slip on the sprocket shaft while the
engine is being rotated. (Substitute a camshaft holder plate in place of the gear cover so that the cam lobes are visible to the eye. The plate
must be installed without excessive play to locate camshaft). Starting with the front cylinder, use the spark plug hole and find approximate
piston TDC. Adjust the pointer on the TDC mark on the degree wheel. Now find true TDC: back up the engine approximately 15˚ (Reading A)
and thread a piston stop in the plug hole until it touches the piston. Rotate the engine in the same direction (backwards) until the piston
gently touches the piston stop and note the reading on the degree wheel (Reading B). Add Reading A to Reading B and then divide by two
(Reading C). Move the pointer on the degree wheel to Reading C without actually cycling the engine, so the piston stop is still against the
piston. Now cycle the engine in the reverse direction until the piston gently touches the piston stop again. The degree wheel pointer should
be at the same point as Reading C. If it is not the same, repeat the procedure until both readings are identical. This will be true TDC!
Once you have an accurate TDC reading for the degree wheel and pointer, set up the dial indicator so that it is solidly on the intake lifter, and
make sure that the dial indicator has enough travel for the lifter to go over the cam lobe. Cycle the motor until the intake lifter is at the
lowest point (heel of the cam, base circle of the camshaft) and zero the dial indicator (verify that the indicator always returns to zero after
the engine is cycled in either direction). Cycle the motor again (in the normal direction) until the intake lifter is at the lowest point (heel of the
cam, base circle camshaft) and zero the dial indicator (verify that the dial indicator always returns to zero after the engine is cycled in either
direction). Cycle the motor again (in the normal direction) until the intake lifter is pushed up *.053". (Do not reverse rotation of the motor as
this will cause inaccurate readings). Check to see if the intake opening event at .053" agrees with the manufacturers cam spec card. Cycle
the motor so the intake lifter is .053" off the base circle on the closing side. Check the intake closing events at .053" with the manufacturers
cam spec card. If both readings agree with the spec card, then the cam is in time (+/- 1˚ is acceptable). If the cam timing was out on either
reading, you must press the gear off and reinstall it in a new position or use our keyed multi-index gear.
*Note: Our cam spec sheets display opening and closing events at .053". This is the most accurate method of degreeing the cam.
Valve Timing
In an effort to simplify what actually happens inside an engine, VThunder® by COMP Cams® invites you to “take a walk” inside a typical
engine, just like the one you have in your motorcycle. We’ll discuss valve events, piston position, overlap and centerlines. Although we don’t
have enough room to explain cam design in great detail, we will try to clear up several of the most often misunderstood terms, and hope to
give you a more clear understanding of what actually occurs in the operation of a four-stroke engine. We’ll graphically illustrate the relationship between all parts of the engine and try to help you understand how the camshaft affects the power of the engine.
We begin with the piston all the way to the top of the cylinder with both valves closed. Just a few degrees ago the spark plug fired and the
explosion and the expansion of the gases forced the piston toward the bottom of the cylinder. This event which pushes the flywheels is
referred to as the “power stroke” (fig. 1). Each stroke lasts 1/2 crankshaft revolution. Since the camshaft turns at half the speed of the
crankshaft, the power stroke only sees 1/4 of a turn of the cam.
As we move closer to the bottom of the cylinder, a little before the piston reaches the bottom, the exhaust valve begins to open. By this time
the charge has been burned and the cylinder pressure begins to push this burnt mixture into the exhaust port where it exits the engine. After
the piston passes true bottom or bottom-dead-center, it begins to rise. Now we have begun the exhaust stroke (fig. 2). This forces the
remainder of the gases out of the cylinder to make room for new air and gas. While the piston is moving toward the top of the cylinder, the
exhaust valve quickly opens, goes through maximum lift and begins to close.
Now something quite unique begins to take place. Just before the piston reaches the top of the cylinder, the intake valve is not fully closed.
The exhaust stroke of the piston has pushed out just about all of the burnt mixture and as the piston approaches the top, the intake valve
begins to slowly open. Here begins a siphon or “scavenge” effect in the chamber. The rush of gases into the exhaust port will draw in the
start of the intake charge. This is how the engine flushes out all of the used fuel. Even some of the new gas escapes into the exhaust. Once
the piston passes through top-dead-center and starts back down, the intake charge is being pulled quickly so the exhaust valve must close
at precisely the right point after the top to keep any burnt gas from re-entering. This area around top-dead-center with both valves open is
referred to as “overlap”. This is one of the most critical moments in the running cycle and all points must be repositioned correctly with the
top-dead-center of the piston.
We have now passed through overlap. The exhaust valve has closed just after the piston started down and the intake valve is opening very
quickly. This is called the intake stroke (fig. 3), where the engine “breathes” and fills itself with another charge of the air/gas mixture. The
intake valve reaches its maximum lift at some defined point (usually about 106 degrees) after top-dead-center. This is called the intake
centerline, which refers to where the cam has been installed in the engine in relation to the crankpin. This is commonly called degreeing.
The piston goes all the way to the bottom as it starts up, the intake valve is rushing toward the seat. The closing point of the intake valve will
determine where the cylinder actually begins to build pressure, as we are now into the compression stroke (fig. 4). When the mixture has all
been taken in and the valves are now both closed, the piston begins to rise, compressing the mixture. This is where the engine builds power.
Just prior to the piston reaching the top of the cylinder, the spark plug fires and we are ready to start again.
16
Cam Recommendation Form
Name:
Address:
VThunder® by COMP Cams®
3406 Democrat Road
Memphis, TN 38118
ATTN: Tech Dept.
City:
State:
Zip Code:
Daytime Phone (
)
WE NEED THIS INFORMATION ON YOUR HARLEY®
Model & Year:
Engine Size:
Bore & Stroke:
Compression Ratio:
Rocker Arm Ratio:
Carb Size:
Intake Manifold:
Fuel Injection:
Cylinder Heads:
Valve Size:
Intake
Compression Ratio:
Exhaust:
Motorcycle Weight:
RPM Range of Engine:
Exhaust
Ported?:
Piston Type?
Yes
No
HOW WILL THIS ENGINE BE USED?
Street
Strip
Street & Strip
Performance Street
Economy Street
WHAT CAM ARE YOU USING NOW?
Stock
Brand:
Part No.
Specs.
CONSIDERING THE PRESENT PERFORMANCE OF YOUR BIKE, PLEASE ANSWER THE FOLLOWING
Do you want more low speed torque?
Yes
No
Do you want more RPM?
Yes
No
Where do you want to improve your bike’s performance?
*Please Copy and Fax this form to us at 1.901.366.1807 or mail copy to the address at the top of the page.
17
General Information
Hours of Operation: Advisory sales personnel are available from 7 a.m. to 8 p.m. (CST) Monday through Friday.
VThunder® is closed Saturday, Sunday and all legal holidays
Technical Assistance: Technical advice is available from any of the VThunder® sales personnel. For assistance call 1-800-967-1066,
FAX us at 1-901-366-1807 or write to: VThunder® by COMP Cams® 3406 Democrat Road, Memphis, TN 38118. We can also be reached
via the internet at www.vthunder.com.
Sales Information: Warehouse Distributors must be able to maintain a representative stock of VThunder® camshafts, valve train
components and other accessories for distribution of jobber accounts. In addition, an initial stocking order is required. Contact
VThunder® for details.
Shipping: Shipping is normally via UPS or FEDEX. Express air freight, airport-to-airport, bus, parcel post, air mail, etc. are possible
methods when absolutely necessary or requested by the customer. Where possible, orders are shipped the same day. Large
shipments to jobbers and warehouse will usually be made by truck upon mutual agreement between the customer and VThunder®
Terms: All orders to jobbers or warehouse distributors will be sent C.O.D. for cash or certified check, unless other arrangements have
been made with VThunder®.
Damaged Merchandise: All shipments are fully insured; therefore, all claims must be made with the freight company. Do not return
damaged merchandise to VThunder® unless prior arrangements have been made.
Returned Merchandise: Merchandise may be returned only if prior approval has been granted by VThunder®. All merchandise returned
for credit must be returned in perfect condition. Merchandise will be inspected at time of receipt. It should be returned prepaid and
insured and may be subject to a handling fee. Credit will be issued at lowest purchase price within the last 12 months.
Warranty Returns: All merchandise returned for warranty consideration, inspection, repair, regrind, etc. must be sent prepaid and
insured. Included must be the sender’s name, address, phone number and an explanation of the problem as well as the work to be
done. All merchandise returned must be accompanied by a written authorization number. To obtain and authorization number contact
VThunder® at 1-800-967-1066.
Prices: All prices are subject to change without notice. Price lists are available from VThunder®. Except as noted, in this catalog, all
products are not legal for sale or use on pollution-controlled vehicles.
Limited Warranty: VThunder® by COMP Cams® warrants that all of its product are free from defects in material, workmanship and
against excessive wear for a period of 12 months from the date of purchase. This limited warranty shall apply for a period of one year
from the date of purchase and shall cover only the original purchaser. This warranty is valid on camshafts only where new lifters and
proper valve springs are used, such as those found in VThunder® kits. VThunder®’s obligation under this warranty is limited to the
repair or replacement of its product. To make a warranty claim, the part must be returned within one year from the date of purchase
to VThunder® by COMP Cams®, 3406 Democrat Road, Memphis, TN 38118, freight prepaid. Items covered under the warranty will be
returned to you freight collect.
There is absolutely no warranty on the following:
A) Any parts used in racing applications.
B) Any product that has been physically altered, improperly installed or maintained
C) Any product used in improper applications, abused or not used in conjunction with proper parts
There are no implied warranties of merchantability or fitness for a particular purpose. There are no warranties which extend
beyond the description on the face hereof. VThunder® will not be responsible for incidental and consequential damages, property
damage or personal injury damages to the extent permitted by law. Implied warranties of merchantability and fitness are limited for a
term of one year from the date of original purchase. Some states do not allow limitation on how long an implied warranty lasts or do
not allow the exclusion or limitation of incidental or consequential damages, so those limitations may not apply to you. This limited
warranty gives you specific legal rights and you may have other legal rights which vary from state to state.
Please note: This catalog has been compiled to the best of our ability. We assume no liability for errors contained herein. It is the
responsibility of the installer to ensure that the components are correct before installation. We assume no liability for any errors made
in components selections or installations. VThunder® reserves the right to make necessary changes in products it manufactures and
markets at any time to improve product performance.
18
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