Engine Block preparation for the Do-it-yourselfer Standard Abrasives Motor Sports Division

Engine Block preparation for the Do-it-yourselfer Standard Abrasives Motor Sports Division
Engine Block preparation for the Do-it-yourselfer
by the Technical Staff of the
Standard Abrasives Motor Sports Division
Block Preparation
Engine block preparation is the cleaning and abrasive operations performed to an engine’s cylinder block prior to the
machining operations (boring, honing, align boring, balancing,
etc.) that set the block’s critical dimensions. For the purposes of
this Guide, we’re going to look at block preparation in a wider
sense and include work on the crankshaft, the connecting rods
and the pistons.
All of the block preparation techniques discussed in this
Guide, surface conditioning, deburring and polishing, can be
done by any do-it-yourselfer using the Block Prep Kit (p/n
260003) from the Standard Abrasives Motor Sports Division
along with a die grinder and a few common hand tools.
Everything the DIY needs to
prep a V8 cylinder block is in
this kit.
The Block Prep Kit contains six types of abrasive products: Surface Conditioning Discs, Grinding
Discs, Cartridge Rolls, Cross Buffs™, Flap Wheels and a 3-foot by 2-in., 320-grit Handy Roll. There
are enough abrasives in the kit to perform basic deburring and polishing on a V8 cylinder block, crankshaft, connecting rods and pistons.
The Kit also includes all of
these tools. Top is the holder
for Discs. Middle is the mandrel for Cartridge Rolls.
Bottom and left are the mandrel pieces for Flap Wheels
and Cross-Buffs.™
Also included in the Standard
Abrasives Block Prep Kit are holders
and mandrels for all the abrasive products. These components are designed
for mounting in a die grinder having a
maximum speed of 18,000-20,000 rpm
and a 1/4-in. diameter collet or "chuck".
-1Standard Abrasives Motor Sports Division - 4201 Guardian St., Simi Valley CA 93063 - (800) 383-6001 - www.sa-motorsports.com
Copyright 1999 - All rights reserved
An air-powered die grinder is desirable because of its relatively low cost and variable speed. It
requires an air source and most air compressors powered by motors rated at 2.5 horsepower or more
will work well. The air system should be equipped with an adjustable pressure regulator. The abrasive
products’ safe speed rating is 18,000-20,000 rpm. If an air grinder’s maximum speed exceeds that, you
must reduce it by using the regulator.
This is a typical die grinder with a
right-angle head and a 1/4-in.
chuck. A die-grinder with a
straight head works acceptably. A
right-angle head can make certain
deburring operations less awkward.
While the never-exceed speed is 18,000-20,000 rpm, the
majority of the abrasive products in the Block Prep Kit will
have best durability when the grinder runs at 10,000-12,000
rpm. Measuring the die grinder’s speed is difficult, however,
most tools cite their maximum speed either in the unit’s
instructions or on a specification plate attached to the tool.
Suppose maximum speed of your unit is 20,000 rpm, but
you want to run it at 10,000. Operate the grinder at half throttle and listen to the noise it makes. Then, run it at full throttle and adjust the pressure regulator such that the noise is
about the same as before. That will approximate 10,000
rpm.
The pressure regulator is important for another reason. It
is easier to manipulate a die grinder with the throttle wide
open than it is to control the grinder and modulate the throt-
tle at the same time.
You may be using an electric die grinder. That is acceptable as long as its maximum rpm is below
the 18,000-20,000 rpm limit. Because electric grinders are often capable of exceeding that by a significant margin, an electrical device allowing the user to reduce the tool’s speed is necessary.
Additionally, speed regulation of an electric grinder will be necessary if you want to use the abrasives
at 10,000-12,000 rpm.
Additional tools required are: a 5/64-in. hex key (Allen wrench), the die grinder’s chuck wrenches,
a medium-sized ball peen hammer, a medium-sized flat nose punch, a medium-sized cold chisel, taps
to fit the bolt holes in your block and a roll of good-quality, duct or "racer’s" tape.
None of the techniques used in a block preparation project are dangerous as long as proper safety procedures are followed, however, misuse of the tools or failure to observe a few safety rules may
result in injury. Deburring and surface conditioning work throws lots of metal chips around, so the first
thing you need to protect are your eyes. The minimum protection is shatterproof eye wear designed
for industrial use. Better is a face shield made of shatterproof material.
Next, you need snug-fitting work gloves. We recommend the Mechanix Wear brand since they allow
a good sense of touch while still offering protection. An alternative is a generic leather work glove of
medium thickness. Avoid thin leather gloves or the very thick units intended for welding and do not use
rubber gloves.
People sensitive to airborne dust may want a respirator mask such as the type used by paint and
body shop workers. These inexpensive, white cloth masks are held to your face with an elastic string.
-2Standard Abrasives Motor Sports Division - 4201 Guardian St., Simi Valley CA 93063 - (800) 383-6001 - www.sa-motorsports.com
Copyright 1999 - All rights reserved
The noise some air grinders make is quite loud. If loud power tools are a discomfort, do your block
preparation work wearing ear protection. Best are the muffs airport workers wear around jet engines.
Acceptable are a set of ear plugs intended for industrial use.
Mechanix Wear gloves can be found anywhere racers buy parts and supplies. You should be
able to find the rest of this safety equipment at a hardware store. Dedicated safety vendors, such as
Lab safety Supply, are also good sources.
The first die grinder operation to learn is changing tools. Virtually all die grinders come with a set
of wrenches used to loosen and tighten the chuck. Typically, one wrench holds the air grinder shaft
and the second wrench turns the chuck’s nut. You loosen the nut, insert the abrasive product’s holder or mandrel, then tighten it, again. Finally, you will attach the abrasive to the holder or mandrel. In
the process of your block preparation work, you will change the abrasive product several times.
Always disconnect the air grinder from the air source and the electric grinder from the power source
when making the change.
Once you start working, move the grinder as smoothly as possible. Grinding in one place will result
in removal of too much material and uneven surfaces. Also, don’t forget to set the speed of the grinder
at 10,000-12,000 rpm.
If you are working with an aluminum cylinder block, use grades of abrasives suitable for aluminum
and, regardless of the grade, use a more gentle touch than you would if you were working on cast
iron. Because aluminum is softer than iron, it abrades faster. If you use the same grinder pressure you
would with iron, before you know it; you will have shaved off too much material. Additionally, when
working on aluminum under most conditions, the abrasive tool will "load-up" with caked on aluminum.
Spraying the tool frequently with a light lubricant, such as WD-40, reduces this problem.
Block Cleaning and Surface Conditioning
If your project starts with a used cylinder block,
you’re probably going to have to clean it before any
abrasive procedures begin. If a used block comes
from an engine that was fairly clean inside, it may just
need to be washed with solvent, then scrubbed with
hot soap and water (Tide laundry detergent works
well) and blown dry with compressed air. Shooting the
solvent and hot, soapy water through some kind of
pressure blaster makes the job easy.
If a high-mileage, used block is your starting point,
it’s probably coated with black, gooey, sludge making
the solvent/hot-soapy-water method impractical. It is
best to have a block that dirty "hot-tanked," a process
that submerges the parts in a hot solvent or caustic
solution. Typically, the block is left in this hellish brew
If you start
with a used
block, here is
an example of
a near-worstcase-scenario
and a great
illustration of
why used
blocks need to
be hot tanked.
Sludge? You
got lots of it,
here.
-3Standard Abrasives Motor Sports Division - 4201 Guardian St., Simi Valley CA 93063 - (800) 383-6001 - www.sa-motorsports.com
Copyright 1999 - All rights reserved
for an hour or so. If everything works right, it comes out of the tank devoid of sludge, dirt and paint.
Hot tanking is a service offered by some auto parts stores, automotive machine shops and engine
rebuilders. Use caution if you are working with an aluminum block. Some cleaning processes and solutions that are safe for iron blocks are not compatible with Aluminum. When in doubt, ask the facility
doing the cleaning if the process they use is safe for aluminum parts.
The majority of DIY engine builds will probably be done with cast iron blocks. If that’s the case with
you, whatever cleaning process was used on your block, you will probably be confronted with a thin
coating of rust on machined sealing or mounting surfaces, such as cylinder head decks, oil pan rails,
timing chain cover mounting surface and accessory mounting pads. Even though the block has been
cleaned, these surfaces should be conditioned to remove rust and any traces of old gaskets, paint,
gasket sealer, and dirt left after hot-tanking. Aluminum blocks will have no rust, of course, but may
have corrosion, gasket remnants or other residue left after the cleaning process.
Using a putty knife or scraper to removing this stuff is not acceptable
because neither will clean those surfaces completely. If your block is aluminum, putty knifes or scrapers may even damage those surfaces. The first
step in block preparation is to clean those surfaces with a Standard
Abrasives General Purpose Surface Conditioning Disc. The Block Prep Kit
contains two different types of them. The Medium grade discs are for iron
blocks and the Very Fine grade discs are for aluminum blocks.
These are GP Surface
Conditioning Discs.
Some engine builders
call them "Gasket
Blasters". The bluegray units are Very
Fine grade and the
red-brown ones are
Medium discs.
Disconnect the grinder, install the Standard Abrasives Quick Connect, 2in. holder pad into the chuck and tighten the nut. The conditioning discs use
Standard Abrasives’ unique Soc-Att™ locking system, so installing the disc
on the holder is as simple as a twist of your wrist.
One of the best features of Standard Abrasives Surface Conditioning
Discs driven by a die grinder is their ease-of-use. Little or no downward
pressure on the die grinder is necessary. The combination of the Surface
Conditioning Discs’ unique abrasive material and the high-speed rotary
motion of the die grinder will do the work. If you apply any significant pressure to the die grinder while using Surface
The key to
Conditioning Discs, damage to the surface being
good work with
abraded may occur.
power-driven
If the work surface is aluminum, additional care
with tool pressure and abrasive grade must be
observed. Use only the Very Fine grade discs and
make sure downward pressure on the tool is almost
non-existent.
After installing the proper Surface Conditioning
Disc, reconnect the grinder, put on your gloves and
eye protection, then start conditioning the head
decks the easy, Standard Abrasives way. Once the
gasket surfaces are down to bare metal, disconnect
the grinder and remove the conditioning disc set-up.
abrasive products is to control the grinder
with both
hands and let
the rotating
action of the
abrasive do the
work. Use only
limited downward pressure,
if any at all.
-4Standard Abrasives Motor Sports Division - 4201 Guardian St., Simi Valley CA 93063 - (800) 383-6001 - www.sa-motorsports.com
Copyright 1999 - All rights reserved
Install the Cartridge Roll mandrel into the die grinder chuck and install an 80-grit Cartridge Roll. Use
that to clear the water holes in the cylinder head decks of rust, scale and casting flash. Doing this will
improve coolant flow.
After you’re done with the decks, reinstall the Surface Conditioning Disc and abrade the rest of the
block’s gasket surfaces, accessory pads and other machined surfaces.
Deburring the Block
You deburr a block for several reasons: 1) deburr the inside surfaces of the engine block to improve
oil return. 2) deburr or radius other inside surfaces that are under high stress, such as sharp edges
and casting flash around the main bearing webs, to make it more difficult for cracks to start 3) deburr
the outside of the block or appearance purposes and to reduce the amount of nicks and cuts you get
from handling the block.
You’ll be deburring with the Block Prep Kits’ Cartridge Rolls or its Grinding
Discs and the Cartridge Rolls will be used most of the time. Deburring to
improve oil return is done to two areas: 1) the oil return holes in the "valley"
between the cylinder banks and 2) the surfaces of the cylinder bank walls
that make up the sides of the valley.
Cartridge Rolls are
the mainstay of many
automotive abrasive
operations. The Block
Prep Kit has four different types: 40-grit,
full-tapered; 80-grit,
full-tapered, 40-grit,
straight and 80-grit,
straight.
Oil is delivered to most of the engine’s moving parts under pressure but
flows back to the oil pan over the engine block’s internal surfaces by force
of gravity. Iron blocks are sand castings and the rough finish left by that
process impedes oil flow. This is seldom a problem for a production engine
in normal passenger car duty, however, in street high-performance or racing engines, it can cause trouble. At high engine speeds oil can be pumped
up into the top of the engine faster than it can drain back. This causes two
problems: 1) a shortage of oil in the oil pan resulting in occasional inconsistencies in oil supply and 2) an excessive volume of oil in the top end of
the engine resulting in oil leaks and oil ingestion into the intake tract. One
way to reduce the severity of those problems is to remove casting flash inside of the oil return holes,
then deburr the holes and the inside of the block valley.
If the oil return holes have a lot of casting flash restricting them you may need to knock large pieces
out with the ball peen hammer and a flat-nosed punch or cold chisel. Once that’s done or if there are
no large oil return
It’s best to use tapered Cartridge
restrictions, open
Rolls to clear the oil return holes
up the Standard
because most of these holes will be
Abrasives
Block
fairly small. Some engines will have
Prep Kit and select
so much casting flash and crud in
either a 40-grit,
these holes that a cold chisel and a
straight Cartridge
hammer may be necessary to remove
Roll or a 40-grit,
heavy concentrations. Two hands on
full-tapered
the grinder makes for better control.
Cartridge Roll. The
-5Standard Abrasives Motor Sports Division - 4201 Guardian St., Simi Valley CA 93063 - (800) 383-6001 - www.sa-motorsports.com
Copyright 1999 - All rights reserved
type of roll you select will be dictated by the size of the oil return hole
you are working on. If it’s a large hole, the straight Cartridge Roll will
work best. A small hole will be better "de-flashed" with a 40-grit,
tapered roll. Typically, one starts from the top or "valley side" of the
block but, don’t forget to roll the block over and look at the other ends
of the oil returns as they exit into the crankcase. In many cases these
passages, as they dump into the roof of the crankcase around the
main bearing webs, will need deburring work, too. Once the oil passages have been cleared with the 40-grit rolls, then go over everything again with 80-grit rolls to smooth the surfaces.
After the oil hole work,
depending on the surface,
use tapered or straight cartridge rolls, to deburr and
smooth valley areas.
The next step is to turn the block back over and deburr the areas
in the valley over which oil flows on its way to the oil return holes.
Generally, this will be the cylinder block walls above the valve lifter
bores and the surfaces surrounding the lifter bores. You may be able
to deburr most of these surfaces using the 80-grit Cartridge Rolls but,
some of the rougher areas will go faster and your abrasives supplies
will last longer if you start with the 40-grit rolls then finish with the
80s. Also, there may be some large, flat or nearly-flat areas where
the 100 grit Grinding Discs may work better. If you are working on an
aluminum cylinder block, use only the 80-grit rolls and the 150-grit
Grinding Discs with a soft touch.
The final block preparation task done in the valley is to Cross Buff
the valve lifter bores. The Standard Abrasives Cross Buff™ is unique in the industry. It was designed
exclusively for automotive use and is the perfect solution to a block preparation challenge: refinishing
the valve lifter bores. Typically this is done with a clumsy brake cylinder hone which, if you can even
find one these days, sometimes can do more damage to the lifter bore finish than good. Using one of
the High-Strength, Very Fine grade Cross Buffs™ from the Block Prep Kit, lifter bore finishing becomes
easy. Install the Combination Mandrel used for both Cross Buffs™ and Flap Wheels, add the hexsocket screw, tighten with a 5/64ths in. hex key, then screw the Cross Buff on that.
These are CrossBuffs,™ a very specialized type of automotive abrasive product developed by
Standard Abrasives
Motor Sports Division.
In block preparation work, the main application of Cross-Buffs™ is the surface
preparation of the valve lifter bores.
-6-
Both Cross-Buffs™
and Flap Wheels
require the long, silver mandrel. When
Cross-Buffs™ are
used, the black set
screw is attached to
the mandrel and the
Cross-Buff™ goes on
the end of the screw.
Standard Abrasives Motor Sports Division - 4201 Guardian St., Simi Valley CA 93063 - (800) 383-6001 - www.sa-motorsports.com
Copyright 1999 - All rights reserved
Of the abrasives in the Block Prep Kit, Cross Buffs™ are most sensitive to grinder speed and should
be run at 10,000 rpm for best results. Also, Cross Buffs™ must be used with a light lubricant, such as
WD-40 or automatic transmission fluid. Dip the Cross Buff™ in the lube or spray it on. Place the Cross
Buff™ at the top of the lifter bore then turn on the die grinder. All that is required is one or two passes through the lifter bore and its surface will be free of corrosion and properly conditioned.
Though cylinder block cracking due to the stresses of high rpm operation is not common with street
high-performance and many race engines, it does happen. If it does, it is more likely to occur in the
structural areas of the crankcase around the main bearings.
It is not necessary to deburr all of the crankcase surfaces.
You want to grind a small radius onto sharp edges and deburr
places where casting imperfections are obvious places for
cracks to start. You may even find casting imperfections in
the sharp-edged part of the main webs that are actually tiny
splits or gaps in the cast iron that surely could become
cracks. Those problem areas need to be carefully deburred.
Don’t forget to lightly deburr the sharp edges and corners
of the main bearing caps. In the case of engines that have the
Lightly round sharp edges on all the oil pump bolted to the bottom of the block and the main oil
main caps, however, do not heavily feed running from the oil pump and into a main bearing cap
radius these edges.
or the block itself, inspect the areas where that main oil feed
goes into the main cap or block surface. Those entry and exit holes may need to be slightly deburred
or chamfered to remove flash or sharp edges that will impede oil flow.
For the most part, deburring or radiusing to eliminate stress risers can be done with 80-grit Cartridge
Rolls but in some cases the 100-grit Grinding Discs may work well. If you are working on an aluminum
block, use only the 80-grit rolls and the
150-grit Grinding Discs with a light
touch.
Some of the surfaces inside the
lower end of most cylinder blocks can
be anything but easy to access, but
with a compact die grinder and the
variety of abrasive products in the
Standard Abrasives Block Prep Kit,
you should have little trouble in work- Some engines, like
ing on the most difficult-to-reach spots. Chevrolets, that mount the
oil pump to the bottom of
Once the work inside the crankcase the block or to a main
is complete, you should turn your block bearing cap, need to have
preparation efforts to the outside of the the main oil feed line tranblock. All casting flash should be sition from the pump body
removed and all sharp edges should to the block deburred to
be radiused. You’d think most of the remove sharp edges that
work on the block’s exterior will be for restrict oil flow.
This is what you call
"heavy deburring". Major
casting flash areas on the
outside of the block
should be attacked with a
40-grit, straight cartridge
roll.
-7Standard Abrasives Motor Sports Division - 4201 Guardian St., Simi Valley CA 93063 - (800) 383-6001 - www.sa-motorsports.com
Copyright 1999 - All rights reserved
ascetic purposes–you want your engine to look as good as it runs. There is a safety reason, as well.
Blocks with lots of sharp edges and casting flash can cut ones hands during the inevitable handling
that will occur during an engine building project. A good block deburring job will greatly reduce the
chances of cuts and nicks. A third reason to deburr the outside of the block is, like the main bearing
webs inside the crankcase, there will be some areas of the block’s exterior where deburring will eliminate stress risers and defray cracking.
The exterior of a cast iron block will be done mostly with 40- and 80-grit, straight Cartridge Rolls
and 100-grit Grinding Discs.. If you are working with an aluminum block, use only 80-grit rolls and the
150-grit Grinding Discs and a light touch.
Once the deburring and radiusing work on the outside of the block is complete, get out your taps
and run them into each bolt hole on the block. It is especially important to do this to the cylinder head
bolt holes. This removes any debris and repairs the threads in any holes that have been damaged.
Either of those problems interferes with proper bolt tightening during the assembly process.
Our finished demo block
shows the comprehensive
deburring job one can do with
the Standard Abrasives Block
Prep Kit.
Once painted, the outside of the block looks professionally detailed. No sharp edges to cut your
hands and no flash nor casting crud to make you
look bad.
-8Standard Abrasives Motor Sports Division - 4201 Guardian St., Simi Valley CA 93063 - (800) 383-6001 - www.sa-motorsports.com
Copyright 1999 - All rights reserved
Crankshaft
The crankshaft is the largest moving part in the engine and
is the device that converts the reciprocating motion of the pistons into the rotary motion that moves the vehicle.
Crankshafts are either cast of nodular iron or forged from
high-strength steel. Regardless of the material, most crankshafts have sharp edges that need to be radiused and rough
surfaces that need to be deburred.
Like the block the first step is to clean the crank. Run a
Crankshafts, especially nodular wire-bristle brush though the crankshaft oil passages. Many
iron units, have a multitude of "engine cleaning" kits have specific brushes for this purpose.
sharp edges, flash and part lines A excellent and perhaps more easily-obtainable substitute is
that need to be removed.
a 22-caliber pistol cleaning kit which usually contains both
the brushes and a cleaning rod that comes in handy for this
Edges of counpurpose. Next, you want to clean the crank’s exterior. This
terweights are
can be done with a cold solvent washing or dipping or with a
best removed
hot-tanking.
with a straight
cartridge roll. It
The crankshaft’s sharp edges need to be radiused. It is not
is not necesnecessary to significantly grind down these edges. Just put a
sary to heavily
small radius on them using either the Standard Abrasives
radius the
Block Prep Kit’s 80-grit Cartridge Rolls or the 100-grit
counterweight
Grinding Discs. You may find some big holes in the counteredges, just
weights and the edges of those holes need to be radiused
remove the
using a tapered Cartridge Roll.
sharpness.
Part lines left by the mold (for a cast
crank) or forging die (for a forged crank)
should be deburred away. A Cartridge
Roll is best for this.
Tapered
Cartridge Rolls
are best for
counterweight
holes. Use a
straight roll and
the diameter of
the roll maybe
too large to
round the edges
of the hole without chattering or
destroying the
Cartridge Roll.
For best results, the diameter of the roll must
always be noticeably less than the hole and in
many cases that means a tapered roll.
-9-
Standard Abrasives Motor Sports Division - 4201 Guardian St., Simi Valley CA 93063 - (800) 383-6001 - www.sa-motorsports.com
Copyright 1999 - All rights reserved
Duct tape greatly decreases the threat of a
nicked journal if you catch a bearing journal
with the tool.
Sharp edges
just outside
the bearing
journals must
be
approached
with care
using a
tapered
Cartridge Roll.
Do not heavily
radius these
edges. In
some cases,
such as this Chevrolet crank, you may be working near the
crank’s thrust bearing surface. Take care not to nick the
thrust surface.
There are parts of the crankshaft deburring process where you
will have your abrasive tool very close to the bearing journals. You
absolutely do not want to abrade those surfaces. To protect them,
wrap each journal with several layers of good-quality duct tape. If
you do nick a taped-over journal, stop deburring, remove the tape
from that journal and put a fresh wrapping on it.
If you make a mistake by touching one of the journals and the
abrasive cuts all the way through your layer of tape, immediately
stop working and re-tape the journal, then continue the deburring
process. After the deburring is complete, strip the tape off the nicked
journal and use the 320-grit Handy Roll to deburr the nick. You will
be able to tell then the nick is properly deburred by running your fingernail over the damaged area. When you can’t feel anything, the
nick has been deburred.
In the unfortunate event
you do damage a crankshaft journal or thrust surface, the Block Prep Kit’s
Handy Roll will usually
repair the problem.
Once you’ve radiused all the crank’s sharp edges, you may find
the flat surfaces of some of the counterweights to be rough or
scarred from the casting and/or machining process. The rough
areas should be deburred using the 100-grit Grinding Disc or an 80grit Cartridge Roll.
Lastly, run a tap through all the crankshaft’s bolt holes to clear
them of debris and repair any minor thread damage.
-10Standard Abrasives Motor Sports Division - 4201 Guardian St., Simi Valley CA 93063 - (800) 383-6001 - www.sa-motorsports.com
Copyright 1999 - All rights reserved
Connecting Rods
The rods are probably the most stressed moving parts in an engine. Most street-high performance
engines and some race engines will use production, forged steel connecting rods. They will have
sharp edges maybe even some casting flash and a noticeable parting line along the rod’s "beam". The
edges and the parting line are stress risers and it’s
important to radius all sharp edges on the rod and
rod cap then deburr and polish the connecting rod
beams.
The first step is to clean parts with either a solvent spray or by the hot-tank process. Next, understand there are three parts of each rod from which
you want to keep abrasive products away: 1) the
rod bolts, 2) the rod cap mounting faces and 3) the
rod bearing mounts. Take care to keep the abrasive
tool away from those areas.
At left is a rod after preparation using the
Block Prep Kit. At right is the production
rod. The greatest value in deburring block
parts comes when you do the rods.
Radius sharp edges on the rod and rod cap using
the 80-grit Cartridge Rolls out of the Standard
Abrasives Block Prep Kit. Generally you’ll use a
straight roll but some of the complex shapes on the
rod caps might require a tapered roll.
Once the edges are radiused, it’s time to polish
the rod beams. Start with a 100-grit Grinding Disc
and remove all traces of casting flash and the parting line left by the forging process.
Begin the process with a 100-grit Grinding
Disc. Remember to let the grinder’s rotary
motion do the work.
The second stage of the rod work is
done with the 80-grit Flap Wheel.
-11-
Standard Abrasives Motor Sports Division - 4201 Guardian St., Simi Valley CA 93063 - (800) 383-6001 - www.sa-motorsports.com
Copyright 1999 - All rights reserved
Once you’ve removed the heavy stuff with the Grinding Disc, select the Flap Wheel mandrel from
the Block Prep Kit, install one of the 80-grit Flap Wheels and further polish the beam surface. It is
extremely important during the Flap Wheel stage to move the abrasive such that the marks it leaves
are parallel to the beam. The final step must not deburr or polish across the beam.
It is very important, to apply the Flap Wheel’s
rotary motion parallel to the rod beam. Applying it
across the beam actually creates stress risers
almost as bad as the ones you are trying to
remove in the deburring process.
This is how the rod beam should look
after the Flap Wheel work.
Pistons
The final step in a block preparation project is
some minor abrasive work on the pistons. Like the
other engine parts we’ve covered in this DIY
Guide, if you are working with used pistons, they’ll
need to be cleaned.
Only use the Flap Wheel on pistons. The
aluminum will abrade rapidly. Only light
radiusing of the piston skirt edges is necessary.
Lightly radius the edges of the piston skirts and
tops. This must be done with care because the
edges will be very narrow and the material is aluminum which abrades much faster than iron or
steel. Use either the 80-grit Cartridge Rolls or 80grit Flap Wheels for this part of the job and remember–you need a very light touch with the abrasive.
You only want to lightly radius the edges not grind
them down substantially.
-12Standard Abrasives Motor Sports Division - 4201 Guardian St., Simi Valley CA 93063 - (800) 383-6001 - www.sa-motorsports.com
Copyright 1999 - All rights reserved
Closing Out the Job
Though many of the parts we’ve worked on in this block preparation Guide will next go to a machine
shop for operations such as boring, honing, rod re-sizing and piston pin-fitting, you want to send the
machine shop clean parts.
We suggest you rewash everything with hot soapy water, give them a water rinse then blow them
dry with compressed air.
Typically, there will be enough abrasive products left in your Standard Abrasives Block Prep Kit such
that, if you get the parts back from the machine shop and find you missed a sharp edge or a little casting flash somewhere, you can go back and remove it before the assembly process begins.
For information on more advanced block prep techniques typical of that used on all-out racing
engines, Standard Abrasives markets a video tape titled "Race Block Prep" (p/n 269847) which covers DIY methods for preparing a block for extreme high output applications.
-13Standard Abrasives Motor Sports Division - 4201 Guardian St., Simi Valley CA 93063 - (800) 383-6001 - www.sa-motorsports.com
Copyright 1999 - All rights reserved
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