Bryan Rose

Has anyone here run these plugs on a superchargered applicaton....Ac Delco R42TS?

I have been recomended to run them in a 500 EFI with an M3 - SC @ 5 lbs Boost Looks to be 1 heat range colder than the stock MR 43 T's the merc book call sfor in stock configuration.

Set the Gap @ .35 with stock ingnition.

Bryan

Crazyhorse

I've run the MR43T plugs in my supercharged carb 509 engines without problems but I don't run hard. Mine make 650@5lbs boost. But as I said, I don't run hard.

kennyo

I've got the same setup as you. I run the 43t's also. When i ran the 42's they seemed to foul easier. Other than rusting, what is the difference in the mr43t and regular 43t's?

BY U BOY

THE ONLY DIFF IS FOR MARINE.

Crazyhorse

Yup, the M is a marine designation and they used to be stainless. Lately I've been buying the MR43T plugs and they have been painted steel.

RaggedEdge

In the older 525 SC Merc used the MR 41 T, a little colder plug than the MR 43 T used in the non blower motors. Ran them in the pair of 525 SC's I had and they always worked fine for me, better a tad on the cold side than melt down a piston.

BadDog

I am running the MR41T with no problems. B&M 250 502.
Get pretty dark if you idle but clean right off once up to temp.

Griff

I run NGK UR5's in my 525SC with a hotter cam and 7.5# of boost. They are the same heat range as the AC MR41T. Never had them foul out, but after a long idle in humid weather they are pretty dark.

Hydrocruiser

NGK's are my personal favortie. I use locktite anti-seize and get easy on and off's.

kennyo

What gap would you run on a procharged 502?