Re: Help from DCOE owners (archive)

If you stick your head under the car while its running you might be able to hear the exhaust leak. If not, wait until it cools and take a good look at it. I would suspect the joint between the downpipe and the center section or a muffler weld seam, but check everything.

Your mains are a little large (I run 125s) but without knowing all the particulars of your setup its hard to say. Check your spark plugs and see if they're fouled - if they are, you're running rich.

Good luck.

: Thanks to you and Corey for the help. This is a great board. Yes it is backfiring out of the exhaust. How do I check for exhaust leaks? Run my hands near the header gasket to the head? Where would the exhaust leaks be, anywhere, like even at the tailpipe? I am running 130 main jets, which appear bigger than what Braden shows in the back of his book for typical 2002 applications (think he shows 120's). What do you guys show. On the timing front, I have been noodling a bit with the Big Dog timing method I read about in the archives. I don't have that method. Does counterclockwise advance timing? I thought timing too retarded would cause backfires.

: : Is it backfiring through the carbs or out the exhaust? If its the former, you're probably running lean. If it is the latter, you likely have an exhaust leak, perhaps exacerbated by a rich condition. The Braden book goes through this in more detail. Let me know if you have any further questions.

: : : I've got 40 DCOE's on my 74 2002. The engine's had some work done on it. It has an E21 head, 300 cam, headers, and 10:1 pistons with good compression (170 even all around). Just rebuilt the carbs. Good thing is it still runs and I have no parts left over. Bad thing is I still have slight backfires on throttle between 3k and 4k RPM. Runs good WOT, and then backfires like made under load coming back down the RPM range. Idle is good and I have synched the carbs. What could be causing this? TIA

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