Backfiring through exhaust

[Mopar to ya]

@$#%&%! I had a thread about this before, so here is the readers digest version and updates. I have some questions and really need advice. Here goes. Car ran great. I installed Comp Cam XE268H cam and lifter kit. Broke in, drove around town, life was good. Degreased underhood and backfired through exhaust immediately on start up. Figured it was wet and would dry out. No such luck. Since then:

turned to TDC, lined up timing marks, verified rotor pointing to #1
new plug wires
new plugs
new cap and rotor
checked for vacuum leaks, none found.

It started with this stuff, which is better than a few days ago. Even ran pretty good, but still popped every now and then. Warmed it up, got timing about right. Stopped popping, or so it seemed. turned idle down maybe 1/8 turn and it dropped idle hard and almost died. Backfired more. Throttle response sucked. Played with mixture screws. got throttle response and popping seemed to stop. Revved and let off, no popping. Go for test drive and as soon as I put it in gear it starts popping.

I am guessing I should do a compression check.

Can a bad or poorly adjusted carb cause backfiring through exhaust?

I am wondering if the ignition module is wet internally. It did get sprayed.

I am sorely in need of some Mopar wisdom. Anyone have any to spare?

 

[magnumdart]

I had a vehicle start this on a very foggy evening. Turned out the coil was going bad. Just a thought, I try not to think the worst, but maybe the cam didn't break in properly. Since it was the last thing you did to the car it is worth looking into.

 

[66dartman]

mine did this after adjusting valves. Thought the worst and started removing valve covers. Turns out wires were crossed for #2 & #4. If it isn't plug wires crossed, pull valve covers and confirm rockers are all ok and no excessive valve lash on any, which could be a flat cam lobe or misadjusted lifter preload. Timing marks lined up for sure? Don't ask me why I am suggesting these things, LOL.

 

[JoeDust451]

@$#%&%! Broke in, drove around town, life was good. "Degreased Underhood" and backfired through exhaust immediately on start

This is most likely the cause, something is still wet even though you "think" everything is dryed out, I've had this happen before years back, drove me friggen crazy & wished i'd never did it :angryfir:, I'd check the coil for wetness/moisture in the tower, The backfiring through the exhaust is do to fouling plugs or bad coil or ignition related IMO, You could have gotten the Pick-up coil in the dizzy wet, the ECU box ect. Try a different coil 1st.