at part throttle, mostly from a standstill or rolling stop i will get what sound like a muffeled backfire. its a single pop that sounds like its coming from inside the intake manifold. valves are not out of sink and i backed the timing off a little too. that did not help. i checked the wires at night and they are fine. i was told it could be a rocker stud working its way out, but then wouldnt it do it all the time. this problem is random, some days it dose it, other days its fine. could it be a cracked rocker? has any one else had this problem, and what can i do to fix it.

 

An intake rocker stud or rocker arm backing off would tend to keep a valve closed, not open. An exhaust stud or arm backing off would do the same, and may affect cylinder exhaust to the point of a light backfire when teh intake valve opens. However, either of these should be accompanied by a lot of valve train noise ling before the backfiring would become a problem.

Backfire is commonly caused by:

• A poorly sealing intake valve(s);
• Incandescent carbon buildup in a combustion chamber(s);
• Advanced valve timing;
• Lean fuel mixture;
• Spark plugs with too high a heat range;
• Poor fuel atomization and puddling in the intake;
• Spark scatter from a worn distributor or cap/rotor problem;
• Cross-firing of spark plugs

 

Ok I have a 355 TPIS intake with a 58mm BBK throttle body on my car with a vortech S/C and 42 LB injectors. The car was running fine on the old intake but I decided to play around. I never had the S/C plumbed into the intake. I set the distrib timing to match the AUJP bin @ 8 degrees btdc. I finally plumbed the S/C into the intake and datalogged the car while in Drive and brake was on have VE master adjust the fuel for the car. My BLM's are around 126 at idle. I am now getting severe popping through the intake only when I hit the throttle. I am guessing I would have to add more fuel to PE, Am I correct? or what would be your guess on this one?