I have a gen 6 502 mag mpi with about 500-520hp, has MSD coil, distributor, 8.5mm wires, and 6M-2L box. I run the NGK BR6FS plug. What do you guys gap your plugs to or what should I gap them to in my set up? I just put a new set in and was pretty sure the old set was gaped to .045, so I gaped these to .045 as well. I am sure this is on here somewhere, but the search feature hasn't been working for the past 2 days for me, and I have read a few different specs.

if it runs fine with a ,045 gap leave it alone and run it.imo anywhere from .030 to .045 should be fine.

Thanks Mike, I need to check the ones I pulled out and see what they are actually gaped to. Haven't done any testing, but having an issue right now, and just want to cover all basis. I will gap to .040" from here on out I think.

.030

With the msd box you should be fine at .045. You might try the NGK projected tip plugs BPR6FS. They are worth a few HP on a naturally aspirated engine.

Bob Lloyd