jca

Hi after some ideas I have a ls1 383ci stroker 246/252/113lsa cam 80pound injectors 5000rpm converter etc it has a intermittent misfire at 4500rpm running ngk tr7 plugs tried gapped at 0.8 it's like spark blow out i have replace crank /cam sensors cleaned and flowed the injectors new pumps checked pressure which is fine swapped coil packs fitted new alternator engine runs perfect most pulls on Dyno gets worse with heat but doesn't do it every run a/Fs are 0.85lamba timing peaks at 28degrees also fitted new ignition leads

Bowtie316

iTrader: (1)

I am curious why the tr7? That seems pretty cold for a NA motor.

What is your static compression ratio?

Alvin@PCMofNC

Do you have a log? That is likely way to much timing especially at that RPM.

jca

Hi have run 6s just trying colder plug as it feels like spark blow out same as boosted engine it has 11.5 comp and is running on e85 tried less timing 24-25degrees I think I have a Efi live log or 2 it basically breaks down at peak cylinder pressures