backfire miss

[jaspermaggie]

I have a strange backfire or miss at 5600 and then the powere comes back and runs to 6200 no problem. It only does this under load, It does not do it when I rev it. I changed to a different plug that ngk recomended but I think it might be something else. My timing is fine. Do you think I have the valves adjusted to much 3/4 turn or is it the carb or distributer? Chevy 355, trickflow heads ,holley 750 vac, hydrolic flat cam. mallory box coil and distributer. What do you think?

[sc racing]

Which lifters are you using? I usually adjust hyd cams "0" lash and the 1/4 turn but in my steet car I have Comp Cams hyd lifters which want .002 lash. But your problem doesnt sound like its an adjustment issue.

[jaspermaggie]

I use trickflow. I got a topend kit and it states 1/2 to 3/4 but sounds like you know more than me. I changed from ngk 7373 fr5 to 7938 bkr5e.

[sc racing]

I wouldnt say I know more than you but I would run the valves again and check all the "simple " stuff like cap,rotor,wires coil connections ect ect.

[jaspermaggie]

I changes the plugs back to what I had I will see if that helps. I just cant think of why it is at 5600 all the time and then it pulls to 6300.

[sc racing]

Anything setup for those rpm's like shift light,two step,timing retard,nos activation, etc etc?

[jaspermaggie]

no my nitrous is at 3200 but that is off. My rex is 6450 and light is 6000. It does feel like the rev limiter but it continues to go. The car is pulling then the backfire or popping is 5600-5700 does that about 4 times then it picks the nose back up again.

[jaspermaggie]

it was the plugs.

[bvr421]

" It was the plugs "
what plugs? why?
It would be nice to know what solved the problem.
Maybe someone else could learn from your experience.