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Discussion Starter · #1 ·
I have a built supercharged 2V with Comp XE270AH cams, stock heads with upgraded valve springs and SS valves. The engine runs fine, but suddenly it started backfiring at idle. The engine idles fine. It's choppy because of the cam, but otherwise it idles at 700rpm and it revs fine, but every few seconds there is a loud backfire. I mean gunshot loud. From a cold start, the back fire starts as soon as the engine is slightly warm.

A/F ratio is right at 1. I pulled the injector plugs one at a time and the problem doesn't seem to be isolated to a single cylinder. I also added fuel thinking the gas could be the cause.

I'm stumped. Getting ready to pull the valve covers looking for broken springs, rockers, cam gears, etc.

This car is a dumpster fire. Has anyone had something similar?
 

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This car is a dumpster fire.
Oh how little you know about dumpster fires.

Did this start out of the blue or with a new build?

Realistically it's one of two things that usually cause a backfire; cam timing or ignition timing. Did you degree the cams per the spec? And what is done in the tune for timing?
+1on the cam timing, i would check tune then cam timing. Perhaps it jumped a tooth.
 

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Discussion Starter · #4 ·
Getting ready to pull the front of the engine apart to check for broken parts. I also have new cams and OPG ready to go in so its a good time to do it. I swear this is the last time I pull that engine apart.
 

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Discussion Starter · #5 ·
Just a quick update. Tore the engine down. Found that the timing wheel keyway was worn allowing the timing wheel to rotate side to side. I thought the balancer would lock it in place, but maybe not. Ordered a new one for $12. Other than that, nothing.
 
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