Spark Plugs
 

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

Re: Spark Plugs
 

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.

Re: Spark Plugs
 

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?

Re: Spark Plugs
 

THE ONLY DIFF IS FOR MARINE.

Re: Spark Plugs
 

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.

Re: Spark Plugs
 

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.

Re: Spark Plugs
 

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.

Re: Spark Plugs
 

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.

Re: Spark Plugs
 

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

Re: Spark Plugs
 

What gap would you run on a procharged 502?