List, racers,
I made a bonehead mistake on the track last weekend. This topic was brought up
recently and we all talked about the great insurance benefits an MSD 6AL box
with rev limiter has to offer. Unfortunately my box is just the 6A. On the
track last weekend I shifted into third but hit fifth, no problem, until I went
to hit third again and hit first gear. OUCH. I sent the RPMS pretty high. I
caught it quickly but obviously not quick enough. After the incident the car
ran fine, but ran slightly rough and had a harmonic vibration like the balancer
was not doing its job. Anyway, after a quick diagnosis I found the upper
timing chain had jumped a tooth. Compression was at 90 psi on all cylinders so
I figured it was a timing issue. After reseting the cam timing I started the
car and found no change in compression and the harmonic vibration was still
there. I have not put a timing light on it as I called it quits for the night
when I made no progress. I didn't want to pull the front cover but it seems I
might need to. I guess I can diagnose the timing issue if I "degree" the cam.
If any of you have experience with this, what could be causing my harmonic
vibration. I speculate the balancer could have been damaged. I am thinking of
putting a timing light on it to see if it is still timed where it used to be
(outer ring could have moved radially on its center?) and maybe I can stop/slow
the motion with a timing light to see if the balancer is damaged and moving
around?
Any other ideas on what I should look for? I don't think that I could have
bent a crank, jackshaft or cam, or affected the clutch/flywheel. I did do a
quick check on the valve adjustment and all clearances seemed within the
ballpark. I didn't find any excessive gaps that would indicate a bent valve.
I also didn't hear any unusual noises when this happened. It just revved high
and I quickly stomped on the clutch.
Any thoughts are appreciated. Please keep negative comments to yourself. I
remember some negative remarks towards the last guy this happened to. Hey,
sh*t happens.
John Over
68 2000
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