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| Re: [GMCnet] Rebuilt Engine Break-In Procedure [message #325483 is a reply to message #325473] |
Fri, 27 October 2017 10:58  |
bdub
Messages: 1578
Registered: February 2004
Location: Central Texas
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Dick Paterson says:
If you are replacing a blown motor, then you must understand that the oil
cooler in the radiator and its connecting oil lines will have metal debris
in them. That debris must be cleaned out. I mean hospital clean. Take the
lines and radiator to a radiator shop for this. Unless this step is done, I
give the new motor maybe 200 miles and BANG, the rods and mains will be out
of it.
There are many opinions on starting procedures and in the following text, I
am simply outlining how we do it here at Springfield Ignition.
It has been known forever that the first 20 minutes from start up on a
rebuild are the life or death factor in initial camshaft survival. With
todays motor oils, that now have minimal anti-wear additives (ZDDP Zinc /
Phosphorous), the start up process is most critical; becoming the single
factor between a 30 minute cam/lifter failure, and any anticipated motor
service life.
During the motor build, the builder coats the camshaft lobes and lifter
bases with a special lube, (if hes sharp he will do the same to the rocker
arm ends and fulcrum). This special lube will cling or stay on those parts
until the motor is started, provided it is not spun over in the interim.
After the motor is fired, the only lube the cam lobe and lifter foot get is
from oil splash (there is no pressure lube to those contact points. This is
the reason that the motor speed must be brought up to 2000 rpm then slowly
cycled through 2000-2500 for the first 20 minutes of run time. There is
insufficient oil spray at idle or low rpm to supply enough oil to save the
cam.
Now here is the important point; anything that can cause a motor to be shut
down during this start phase will surely impact the cam/lifter run-in. If
you do your homework before you fire the motor, you will reduce the chances
of having to shut down. We have the letters S O - V F W written large on the
wall beside the run in test stand, and on its instrument panel. If the motor
is still in the coach, write them on a piece of masking tape and stick it
where you see it. Our rule is that these letters must be gone though twice,
no exceptions, because the motor must fire right away, like a modern fuel
injected motor, with the first turns of the starter. This is our letter
check for a carbureted only motor;
(S) SPARK - You have to be able to see it. We always finish assemble the
motor at TDC #1. (Number one spark plug at Top Dead Center) You will need to
verify yours. Find and mark the slot in the balancer with white out then
with a ½ inch breaker bar on the harmonic balancer center bolt, have some
one hold their finger in the #1 spark plug hole. As you rotate the motor
there will be air pressure at the plug hole as the piston approaches TDC.
Line the mark under the timing tab at about 10 degrees. If you dont do the
finger pressure test, then the slot could be under the timing tab, but the
motor will be on TDC #6. This is called half out of time and will cause
backfire or sneeze and wont start. It is crucial that the lube paste not be
wiped off the cam. The motor must be left undisturbed at TDC #1 until you go
through all the letters. Next step, use a test light and check for spark
with key on at the coil positive (+) terminal or BATT pink wire to the HEI
distributor.
(O) OIL - We fill the sump with 15w-40 Shell Rotella T (regular HD
gas/diesel oil) and add a container of GM EOS. If youre not sure what
your motor builder did, take the rocker covers off (before you have the A/C
brackets on) and pour some of the oil and EOS on the rockers and valve stem
ends. Leave the rocker covers off until you pre lube the motor later.
(V) VACUUM - Verify that all vacuum ports into the intake manifold and the
carb base are attached or capped off. Any big vacuum leak will cause you to
shut the motor down. We attach our vacuum gauge to a manifold source.
(F) FUEL - You should have fresh gas, especially if the vehicle has been
sitting for any length of time without STA-BIL in the fuel. If you do not
have an electric pump, then carefully fill the carb bowl through its top
vents, not by spinning the motor over. Go over all the fuel line connections
for tightness. Fuel leaks are a major cause of fires!
(W) WATER - Filling the radiator is always a slow chore, due to the air
locks created in the block. Take the heater hose connection at the back of
the intake manifold off (above #8 cyl) and fill until you see water
here. Now go over each hose clamp on the water pump and rad. A tight motor
is going to create a lot of heat and any cause for a boil over will mean a
shut down.
Now we go back through our letters for the second time.
It is now time to pre-lube the motor. We put our homemade (from a cobbled
distributor base) tool down into the distributor hole to engage the oil pump
drive shaft. Spin it backwards with an air wrench or good 3/8 drill until
you see oil pressure on the gauge and oil at the rocker arms; this could
take 5 minutes or more. Drop the distributor into the motor, pointing the
vacuum can back at the firewall, set the dist. cap on loose (without plug
wires on it), now, peeking under the cap, rotate the dist. base until the
rotor tip points at a plug wire tab inside the cap. Tighten the dist. hold
down clamp. That plug wire tower has now become #1 cyl and after you put
that plug wire on, install the plug wires following the firing order counter
clockwise around the cap. Then verify the firing order twice. (1 8 4 3 6 5 7
2) Any crossed wires could cause a backfire. Now is the best time to hook up
your timing light, keeping the wires away from belts exhaust manifolds,
etc..
The motor is now ready to start. We make sure we know where the fire
extinguishers are and have additional radiator water on hand. Turn up the
idle speed screw on the carburetor linkage. Look into the front ½ of the
carb and move the throttle, watching for a squirt of fuel. Turn the key,
pump the throttle, and the motor should start on its first revolutions. IF
IT DOES NOT, then something is wrong and you need to go back through the
letters ( S ) SPARK and ( F ) FUEL. Above all, DO NOT continue spinning the
motor and wiping all the assembly lube off the cam. If the motor is fuel
injected, then you must work your way through the spark and fuel maps to
verify all the sensor current parameters.
Once it fires, hold the RPM up to 2000 and verify the timing is about 15-20
degrees. Then begin to gradually cycle the rpm up through 2500 and back to
2000 for at least the next 20 minutes, keeping an eye on the water temp and
oil pressure, and of course, any fluid (or vacuum) leaks. Never let it idle
during this first run as there is insufficient oil splash at idle to save
the cam.
We now shut it down and let it cool off completely. This takes 3 or 4 hours
and allows the valve springs to go cold and take their set.
We use a FILTERMAG on every motor so we leave the break in oil for the
next 2 ½ hours, you may want to change just the filter then, to get rid of
as much internal trash as possible. The best way to complete your run in is
to drive the coach, putting the motor under load. The break in oil should be
left in for at least 1500 miles, topping it up as necessary. Thereafter you
can select a motor oil of your choice. (Our choice is always a synthetic!)
This break in procedure will give your motor the best chance to deliver a
long service life.
Dick Patersons Springfield Ignition
705-325-4554 dick@paterson-gmc.com
www.paterson-gmc.com
GMC Engines Transmissions Carburators
Distruibuters Ignition Wire Sets
bdub
-----Original Message-----
From: Gmclist On Behalf Of Ray Erspamer
Sent: Friday, October 27, 2017 9:07 AM
Subject: [GMCnet] Rebuilt Engine Break-In Procedure
I'd be interested in hearing what members of the group think would be the
best break-in procedure.
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bdub
'76 Palm Beach/Central Texas
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