What sparkplugs do you use in AFR heads? I had a tech cross reference the reccomended Chanpion( because they didn't stock the Champions) in a NGK and the plug they gave me was kind'a weird. Thin electrodes, small gap, about .020. The boat ran ok, I'm just curious what other people are running. Thanks, Ian

I run NGK's with heat range 8 (NA 502s). I can check the part number when I go to my boat shed this weekend if you need.
Tom

That would be helpful. Thanks.

When I built my motor I called the NGK tech line, the guy spent about ten minutes with me and was very knowledgeable.

Might be worth a call 1-877-473-6767 prompt #2

Thanks, i'll try that.

I used the NGK R5671A-7. The -7 is the heat range. -10 is coldest and -1 is the hottest. I think on these heads they only go to 5 or so. I'm running the -7's. N/A 502

Dave

Axa, those sound familiar. Are those the ones with the thin electrodes?

I'm not sure if they are thinner....not sure what you are comparing them to. That's what I'm using though. My heads are the 305cc CNC'd to 315 cc.

Dave

I am presently running the NGK 5671A-9. This plug does cross reference for use in the Mercury Racing HP900SC motor.
Also, this plug was a recommendation from Dean Nickerson.
I fielded this question to one of our members, Wette Vette. He suggested that I could go to the -8's, with my NA 540, which is equipped with the AFR 305 CNC'd Chamber heads. He didn't think that the -9 would be a problem but could foul out easier rather than the hotter -8 variety.
My engine builder installed the Champion RC9YC4 plugs for the dyno pulls.
I will probably go with the -8's come this season.

Those are the one's I am currently using.