I've got one for you,a buddy of mine has a Spitfire that he's put a 4.3 chev motor in.He was having problems with it running good one minute,then it would be backfireing and spitting gas out the carb the next time he tried to run it .He was sure it was the carb,but i thought it sounded more like timing issues.I went through the carb for him(2v dual-jet),choke set right,new needle/seat and gaskets.The only thing i found was alot of dirt in the inlet and bowls.He put a new timing chain set on and said compression was healthy when he did a test.Anyway,i went to check the timing and found the #1 plug was getting no spark.All the others were.I thought he had a bad plug wire so i put a different wire on it.I set the timing at 10deg. and the thing ran like a champ.He tried to start it a couple of days later and it was doing the same thing again,checked the #1,no spark???I Took the cap and rotor off and everything looks brand new,weights and springs work nicely.His vac.advance can leaks,but thats not getting vacuum at idle and would only give him a little vacuum leak,maybe a stumble at worst.Any ideas?

 

I'm afraid this doesn't meet the TGO board rules for 3rd gen applicability.

Sorry.