500 hp plugs

[donzi2287]

What plugs go in a 502/500hp? I have used the Delco MR 43 T and the marina recommended an NGK. It has longer threads than the Delco. Will the longer threads work and maybe this is why I have been backfiring.

[J.T.]

I used NGK BR6FS's in mine without any problems.

[donzi2287]

Are those short threads or long?

[J.T.]

I don't recall what the thread length was.

All I remember is that it ( BR6FS) was one of the recommended
plugs used for HP500's in my mercury hi perf. manual.

I've used them in a couple different HP500's without issue

[Geronimo36]

BR6FS is the std. hp500 plug. The MR43T should be the equivalent plug.

[donzi2287]

Thanks again!!!!!