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Old 10-13-2018, 06:55 PM   #18
Cape Codder
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Join Date: May 2010
Posts: 991
Default Re: Terriable backfiring

FIRST I want to thank everyone that has responded to my "Terrible backfiring" post.

We have tried: changing the distributor body & cap, re-gapped the points, changed the condenser, changed the coil & coil wire, re-timed the engine, checked for vacuum leaks at the intake/exhaust manifolds, did I say retimed the engine cause I forgot to tighten the screw on the cam, used a jumper to check the ignition switch, adjusted the GAV from almost closed to 1/4, 1/2, and maybe as much as 3/4. After these few checks, we still have a Terrible Backfiring.

Soooo.......we are thinking of changing the plugs. We found the washers? on the bottom of plugs crushed and don't seem to be sealing. Don't know for sure about that but they sure are flat. However, the plug tips are a lite tan color with no oil or soot.

I have Champion W16Y plugs in there now but which one do most use looking at the below chart which was posted by someone on this site? Should I have a hotter or colder plug?

Champion (hotter down to colder):


Thanks for any help you can supply because we are at witts end with this problem.
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