Correct spark plugs for PCM Pro Boss 5.8

Friend has a 92 nautique with a PCM engine. Cover on the carb states pro boss 5.8 so I assume this is the 285HP engine with GT40 heads? It certianly has a lot more poke than my 2001.

If so should the correct plugs be NGK BPR6EFS? (I'm in the UK so NGK are easiest to obtain).

I have some bpr6efs plugs and on comparing the autolite ones removed the NGK ones are slightly longer on the thread part. I think this is where the "E" in the bprefs comes from.

So is it possible the previous owner had installed the standard output plugs (think these are NGK BPR6FS) and it's run ok with them?

I'm concerned with use the longer plugs in case the piston bumps into them.

I understand I can check for GT40 heads by looking at the number on ribs cast into the end? 3 ribs should be a GT40 so if so can I safely use the BPR6EFS plugs?

Anyone care to confirm?

Has anyone tried E3 spark plugs? www.e3sparkplugs.com
I have only heard good things about them and might have to try a set on my PCM 351.

Autolites are not available in this country. Generally its NGK or champion plugs.

Fitted the BPR6EFS and they are fine.

horkn wrote: NGK's work great and are 100% direct swaps for autolites.

Are the NGK's in the Martinique that won't rev past idle??!!

Kapla checked yesterday at skidim, the Autolites 764 that I have work for your engine with the Gt40s and the protec ignition, Wanna trade them for the Tshirt?

LOL.

That's not the reason. Although I would have posted the same thing if I were you. ;)

It's a SB ford, I have run NGK's in all my SBF vehicles with no issues.

As a matter of fact, I put in new NGK's when I first bought the boat in 2000 and it ran great with them:)

kapla wrote: I run NGK also in my engine, with gt40p heads..maybe also thats why I can;t make it past the 4500 rpm at wot

I use the BPR6EFS in my 5.8 HO. Did WOT 5200 with stock prop, now 5000 with new Acme #328.

NGK is the only brand thats easy to get here too. But often get bad press.

michiel200 wrote: kapla wrote: I run NGK also in my engine, with gt40p heads..maybe also thats why I can;t make it past the 4500 rpm at wot I use the BPR6EFS in my 5.8 HO. Did WOT 5200 with stock prop, now 5000 with new Acme #328. NGK is the only brand thats easy to get here too. But often get bad press.

those are the ones I have in my engine also just confirmed with an old post I did...
I`m possitive the reason I don´t see more rpm´s its ignition realted (protec) or the tach not giving accurate readings...