Dave, if your timing is floating around that much in a couple days, you
might check for the following:
1. See if the distributor mounting bolt is loose.
2. The harmonic balancer outer ring may be loose enough to have rotated
on it's rubber cushion and your timing marks are not what they seem.
3. I would try starting the motor and advancing the distributor and see
if it smooths out. Then check the timing again and see what it reads.
Often times your best judge of how an engine is running is your ear!
4. Best thing is to find TRUE TDC by using one of those devices that
are inserted into the #1 spark plug hole and you manually rotate the
engine back and forth to its limits. TDC is the average between the 2
limits. Compare this with the timing marks on your balancer and tab.
It helps to have a balancer with a timing tape on it, but you can
improvise for finding TDC. If things don't agree, sounds like either
balancer problem (more likely) or timing chain jump (less likely). When
you get to true TDC, pull the distributor cap and see if #1 plug is
almost ready to fire.
HTH...Wally / Templeton, MA
53 3100
>
> I have a chevy 350 in my 67 nova and it is running TERRIBLE. <missing,
> sputtering, and even an occasional backfire. I set my timing at 8
> before
> TDC, dwell at 30, and adjusted the carb (600 holley). It helped for a
> day or
> two, then it was even worse. I checked my timing again, days later,
> and it
> was somewhere near 18-20.
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