MR41T's in a Cigarette with 502's, blowers making about 5 lbs of boost, approx 600 HP...

These are the plugs in the boat, getting ready to replace, curious what I should set the gap at. Thx.

.035”

.03551.....

.03123

.035

What type of ignition do you have? My old MSD and my new Daytona Sensors called for a larger gap due to the added spark power they provided. If your running stock then .035" otherwise go with the ignition manufacturers suggestion. Other than that you are running really rich.

D.U.I ignitions recommend 0.055 which doesn’t work well at all.

MSD... distributors and 6AL boxes...

In that case max .040”

The strength of msd box is being able to fire an otherwise fouled plug. Keeps larger cammed lower quality idle mixture engines idling well. Larger gaps don’t do much but eat ignition parts (caps, rotors wires) in small block and big block chevy engines.

Which coil are you running? Some of the newer coils put out a lot more current than the old Blaster. In big bore engines spark strength can make a measurable difference.