I was trying to set the timing in my '87 camaro 4bbl the other day. I want it set to 5 deg advance. I took the appropriate plug off of the distributer and and used a timing light to set timing. The timing started at 0 deg or slightly retarded. when I turned the cap, the timing advanced smoothly until about 4.5 deg where it immediatly jumped to 15 degrees advanced. What the heck is going on?
I set the timing back to 5 deg advanced from there and it was fine. Then I shut off the car and restarted it and I'm at 5 deg retard. Any suggestions?
A friend of mine at work seems to think that it may have something to do with the mechanical advance in the distributor. Could this be? Where would I get an adjustable mechanical advance kit to replace parts? How would I test for problems?

 

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I would try to lock the mechanical advance downand see it the timing stays steady. If the timing is boucing around during the timing process, then I would also look into testing the ignition coil. If you have an msd ignition, check on this site for msd ignition problems.