High RPM Spark Breakdown

[JDP]

I have a general question to ask in regard to spark plug gap. Would a low compression engine, say 8.5:1, require a smaller plug gap that a higher compression engine if using the same coils and ignition, etc.? I have a low compression engine and I notice what I think is a ignition breakdown at redline, 6000 RPM, where engine is missing slightly.

I installed the MSD Blaster Coils 8207 and thought I could run a larger gapped platinum plug with the hotter coil than what was in the car originally. The original coils are Bosch, approximately 10K Volts, and the manufacture's recommended gap is only .028". The NGK plugs came with a .039" gap, which may be too much for this low compression engine. I will reduce the gap to .035" an see if that helps. Thanks, JDP

[Gaz64]

What engine and what carburetor?

[JDP]

I'm running a BMW 5.0 V12 with stock fuel injection, ECU, etc.

[Gaz64]

What's wrong with the Bosch coils? 10K volts, where's that info come from?

[msdtech50]

low compression were your at should be anywhere from .34 to .45 when the compression is higher the gap needs to be smaller. then when you go to power adders( Nitrous, turbo, super charger, race fuel) the gap will change

[Gaz64]

low compression were your at should be anywhere from .34 to .45 when the compression is higher the gap needs to be smaller. then when you go to power adders( Nitrous, turbo, super charger, race fuel) the gap will change

Perhaps gaps of .034 to .045 would be more correct.

[msdtech50]

yes so if you want you can start at .40 and run it for about a week then check the plugs and go from there