The Rebuilding Process
CONNECTING RODS
1. Check the parallelism, alignment and the roundness
of the connecting rods.
2. Replace or recondition the unaligned or bent connecting rods.
3. Replace all the connecting rod bearings.
4. Inspect rod bolts for stretching and thread damage. If in doubt, replace the rod
bolts. This should be done
before the connecting rod is resized because some bolts are
pressed into the rod and will cause distortion
that will be corrected during the resizing process.
CRANKSHAFT
1. Inspect and clean the crankshaft-clean with a cloth over the oil ducts.
"Eliminate burrs".
2. Use a nylon cleaning brush to thoroughly clean all oil passages in the
crankshaft.
3. Check the alignment- replace a bent crankshaft.
3. Rectify scratched, scored, conic or oval shaft journals. Usually grinding is
necessary to correct problems.
4. After grinding the crankshaft, it must be micro polished to remove peaks that are
created during the
grinding process.
CAMSHAFT
1. Inspect and clean the camshaft.
2. Clean camshaft with hot water and blow dry. Wash and blow out any oil galleries.
3. Replace camshaft if bent or if the cam lobes are worn.
4. Always replace all lifters when installing a new camshaft.
5. If re-using the old camshaft, lifters must be installed in the original position in
which they were removed.
6. Use and approved lubricant on the cam lobes. Engine oil is not satisfactory for a new
camshaft. It will be
wiped off the lobe before you have even completed assembly. Molybdenum-Disulphide grease is the
preferred choice of many engine builders for cam lobe lubricant on new
camshafts.
CYLINDER BLOCK
1. Inspect the main and cam bearing bores for size and roundness.
2. Main bearing bores may require align honing or boring to correct size, round, or
alignment problems.
3. Inspect cylinders for straightness, out of round, and size. Bore oversize to correct.
4. Inspect deck surface for straightness and surface imperfections. Mill decks to correct.
4. Inspect complete block for cracks by magnafluxing.
5. Thoroughly wash complete block with soap and hot water to remove all dirt and grinding
particles.
Special attention must be given to all oil gallery holes. These must be
cleaned with nylon cleaning brushes.
6. Cylinder walls should be cleaned with lint free cloth and ATF or equivalent to remove
all honing residue.
PISTONS
1. Clean the old pistons. Do not wire brush ring lands. Use and old ring or ring grove
cleaner, taking special
care not to scratch the sides of the ring lands. Do not cut the bottom
of the ring land.
2. Replace cracked or worn pistons. Replace pistons with excessive wear in the ring lands.
3. Inspect piston skirts for being collapsed. The lower portion of the skirt should be at
least as large, if not
several thousands of an inch larger than the center of the skirt. On
used or damaged pistons, you may
find the bottom of the skirt to be smaller than the center, which will
usually cause piston knock.
4. When installing piston on press fit rod, it is recommended to use a rod oven to avoid
tight piston pins.
5. Oil piston pin holes immediately after installation. Transportation of pistons with dry
pin bores can lead
to pin bore scoring.
6. Install rings with a ring expander. If the rings a bent by a winding method often used
to install them on the
piston, they will not provide an adequate ring land seal, causing blowby and
oil consumption.
CYLINDER HEADS
1. Clean and inspect cylinder heads for cracks by Magnaflux testing.
2. Check heads for warpage. Mill to correct.
3. Inspect all valve guides and valve seats for wear and replace as necessary.
4. Inspect valve stems for wear and valve heads for burning. Replace as necessary.
5. Check valve springs for cracks and replace any that do not satisfy spring pressure
requirements.
6. Wash heads with soap and hot water, taking special care to brush valve guides to remove
machining debris.
VALVE TRAIN
1. Inspect push rods for straightness. Check ends of push rod for damage or excessive
wear.
2. Inspect rocker arm fulcrums for wear. Check push rod ball socket on the rocker for
wear. NOTE: Rocker
arm and fulcrum or ball must be kept together because they create
mating wear patterns and become not
interchangeable.
3. Inspect lifters for wear on camshaft mating surface and replace as necessary.
4. On overhead cam engine, Inspect rocker arms that run on the camshaft for wear. Always
install new
rocker arms when replacing a camshaft on this type of engine.
5. Special care must be taken not to damage or distort valve seals during installation.
The seal can be
damaged when sliding over burred valve keeper grooves.
SPECIAL NOTES ON REBUILDING YOUR
ENGINE:
1. If you have contracted the machining operations out to an engine machine shop,
you should inspect all
work performed before starting to assemble the engine. If there is a
problem with the machine work, you
should bring it to the attention of the shop before engine is assembled. Most
shops will not consider
warranty on machined components after they have been in a running
engine.
2. Inspect all new, replacement parts for damage or imperfections before installing in the
engine. It is far
easier to try and obtain a replacement for a defective part before it has
been installed in an engine than
trying to argue that the failure was caused by the part and not improper
installation.
3. This is the most important part of the rebuilding process. CLEAN.
Each and every component in the
engine most be clean. The machined parts, the new parts, tools that you
use, and of course, your hands.
I have seen more rebuilds fail because of built in dirt when assembling an
engine than any other reason.
Each little piece of dirt acts as a miniature machine tool which starts
grinding and cutting new components
as soon as the engine is placed into service. I have even seen several
engines that had dirt related
damage from just rotating the engine during assembly. These engines had never
even been installed in a
vehicle.
Remember, CLEAN parts, CLEAN
hands, CLEAN Tools |