Hi Gang,
A year ago I helped a friend drop a new 225ci V6 into his 67 Jeepster.
He has heard me brag about the people's knowledge this list and has asked me
to forward this question.
There are several guys in our group that have a total mystery in our 225
odd-fire Buick V6 motors. Most of these are in '67-'73 Jeepster Commandos,
or early CJ's, but one is even in a boat. To my knowledge this "problem"
doesn't exist with the Buick 231 either odd or even-fire motors.
The symptom:
The engine has an initial timing of 30-40 degrees BTDC!! The original
setting is supposed to be 8-12 degrees.
If running a points distrib. there is about 12 degrees of vacuuum advance,
+ 18 degrees of mech. advance. In mine, starting at 37 degrees, this yields
a total advance of 67 degrees! I CAN NOT retard below 30 or the engine will
stall. HEI conversion yields the same result. The engine seem to run
fine, with decent mileage, but perhaps the low end power is compromised.
What we've checked:
Initial thought was that the harmonic balancer is off. Pull the head, set
to TDC and the piston is squarely at the top.
Timing chain off a tooth. Nope. Bad cam? Seems unlikely since we have
different manufacturers, but the guy with the boat degree'd his and says
it's right on.
All of these have low restriction exhaust pipes (mine has a flowmaster going
into 2 1/2 in pipe instead of a muffler) and the guy with the boat is
running straight pipes. We thought of backpressure, but these engines fire
up immediately and I would assume that this is before any back pressure
could have an effect. Same would be true for a massive internal vacuum
leak.
Plugs look clean and uniform in color. All have spark. Serial numbers off
the dist was used to verify correct cap/rotor/points/condensor (there in an
even-fire version for the HEI, and several different caps for the Delco or
Prestolite points setup depending on year).
If you know about odd-fire motors, you know that if you ran even-fire
ignition, 2 cylinders would fire at the correct time, 2 a little off and 2
WAY off. But compression is equal in all cylinders and when I pull the plug
wires, I get a drop of 50 RPM from each one. If it were 2 cylinders that
were firing at the wrong time, I would get less of a drop with some, more
from others.
All the motors, to my knowledge are 0.030" over, but there doesn't seem to
be a common thread. If anyone has even heard to this happening please let
me know. I'm no pro, but some very experienced mechanics are stumped after
spending MANY hours under the hood (I'm sure no one EVER spends time on a
Tiger, right? ;-) and at this point we're looking for help.
Sorry to be off-topic and long-winded, but if you have any ideas I'd love to
hear them.
Thanks,
Michael
mderksen@microcide.com
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