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Discussion Starter #1
Hi, all. Have a perplexing problem. I've got a 66 GT convertible that is driving me nuts. Car runs great, has plenty of power but at idle has an annoying pop in the exhaust. It's not very loud and is intermittent but seems to become more pronounced as the car heats up. Does not seem to cause any drivabilty issues. I've tried adjusting the mixture screws on the carb, adjusting the timing and adjusting the valves. All with no luck. Anybody got a suggestion? I'm fresh out of ideas.
 

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Got a small leak in the exhaust system up stream? Cross firing spark plug wire or distributor cap? Have you run a compression test to check for a possible broken valve spring, burnt valve, flat cam? Bruce
 

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Discussion Starter #4
Thanks for the replys. No smog on the car and I was running a fairly rich mixture which seemed to curb but not cure the popping. However I did have the exhaust manifolds off this past winter to detail them. Hmmmmm, maybe I do have a slight exhaust leak? I haven't noticed it but I'll certainly check it out tonight. Thanks for the tips, I'll let you know what I find.
 

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Discussion Starter #5
Update:

Ok, I swapped out the cap and rotor. No change. Checked the plug wires. Getting spark at the plug on all wires. Checked out the Pertronix. Regapped and checked ground wire. Still no change. Replaced plugs. A few were carbon fouled. Probably from the semi rich mixture I was experimenting with. Viola! Problem solved!!!

Yeah, not so much. It stopped popping upon start up and at idle. Took it for a drive of about 2 miles. Got out and checked, no popping. Drove a few more miles, checked again, no popping. Called friend to tell him problem fixed and I heard a pop. Then another, and the them a few more. Drove home and the popping was back to the way it was before. Other friends are suggesting stuck/collaped lifter, stuck valve or exhaust valve erosion(Not sure if it has hardened seats).

Back at ya guys(and girls). Any other suggestions before I tear this thing apart?

Thanks,

Chris
 

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Suggestion: 1 pint of Marvel Mystery Oil in the crankcase, 1 pint in the fuel tank. If that doesn't work, 1 qt ATF down the carburetor at 3000rpm until you stall it and let it sit overnight.
 

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Discussion Starter #7
Thanks bartl! I'll give the Mystery Oil idea a shot. Question thou. After I try the ATF trick, I need to change the oil...correct?
 
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