jskorz

Looking for spark plug recommendation for street driven 455 , 10.0 to 1 compression , Keith Black hyper. pistons , rebuilt quadrajet , cam. - 496" int. , 520" exh. , 224 int. 234 exh. @ .050 duration , factory 1978 40k volt High Energy Ignition for now ( stock ignition curve ) , 3.08 rear , Speedmaster Heads .

Looking for spark plug manufacturer and part # ( will not use champion plugs )

Thanks in advance

bccan

ASSuming they’re the same as Edelbrock Gen 1 heads, mine are NGK BKR 7E. I don’t know if they’re ideal as I haven’t removed one in 10 years despite a new set sitting on the shelf.

….

edzolz

There is a spark plug cross reference in the Tech Editor's Desk section.

BillK

What do the Speedmaster heads recommend ? That would be the first choice.

Most aluminum heads use a 3/4" reach gasketed plug. Champion RC12YC would be my starting point. Not sure why you dont like Champion but you should be able to cross reference that number.

olds 307 and 403

A lot of people had issues with Champion plugs. My Uncle would not run them in anything, except small engines, which seemed Ok. My Boss who was a licensed mechanic would not stock them till Champion came out with the truck plug, it took a money back guarantee, I believe, a really nice plug, nothing but issues with the regular plugs, this was 20 years ago. The rumour was once lead was removed from fuel, Champion plugs ran terribly but who knows. Obviously, all the plugs, except maybe NGK, have changed their design and place of manufacturing over the years.

Duh

NGK BKR7E is a good start from the info you gave.
Champion made excellent race plugs up to a few years ago. Recently quality is not there and they discontinued alot of part numbers. I used to run C61YC's in my old motor 11:1. I had one NOS set of C63YC that I ran in my current motor, ran good but could not get a new set, discontinued.

cutlassefi

Also known as a 4644. BKR6E would be a 6962.
Hope this helps.