new engine backfire

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Mar 24, 2004 | 06:32 PM

tastyklair

Thread Starter

Elder User

Joined: Jan 2004

Posts: 867

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From: Eastern Pa

new engine backfire

Started my 400 up last night and it started right up. New everything inside. Raised the idle to about 2000 for the new cam and all was good for about 4 minutes then a very loud backfire out the right side. As it continued to warm the backfires became much more numerous and seemed to be random. They were LOUD. I had to shut it down and it was late so left it for later when I get some time. Any thoughts on a backfire like this. I'm going to recheck timing and will also check the lifter preload again. What caused loud backfires out the exhaust? I'm used to chasing down intake pops but not exhaust.

Mar 24, 2004 | 07:58 PM

danlee

Postmaster

Joined: Aug 2001

Posts: 4,270

Likes: 5

From: Delaware

Unburned gas in the exhaust, being ignited by the hot exhaust valve. Check the color of your plugs.

That is only one possibility, another is crossfiring. Recheck all your plug wires.