625hp - Iron Heads, 1050 Dominator carb
Had Champion RV15YC4 - which ran fine, I've been told this is to hot of a plug, I swapped them out for NGK BPR6FS while doing a tune up , I have not tried them yet, just looking for other opinions/options, and recomended heat range

thanks,

I think the NGK are the best thats what I run in mine. And all my other buddys run them to no problems.

With a similar set up, we use the NKG 5672A-8 or the Autolite 3911 which are both a similar heat range. The NKG-6 range plug is definitly hotter than the 8. I could see a 7 but don't see a reason to go any hotter.
Except for cylinders 1 & 2, we get a nice brown/toast color. 1 & 2 in the BBC are generally fat...especially with a single plane intake.

i agree,i like the ngk plugs.5672a-8 would be my choice,a 6 would be hotter than i would ever run in any marine engine.

Which heads do you have? If they are GM heads and take a tapered seat plug, you shouldn't be running a projected tip plug. the BPR is a projected tip.What is the compression? What is the cam?

Those items will determine the heat range. Without knowing any specifics on the engine, I would say that the 6 is a little hot. I would go to a 7 with the NGK plugs. If they are the GM heads, then you need a R5673-7.
Eddie

My heads are Brodix iron, & take a tapered seat plug, ran the boat last night & it was hard to start once hot, I will try 7 or 8...