BBC Spark plug help. Not MR43t
07-10-2020, 10:20 PM
#21
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Originally Posted by BillK
The other thing is you probably should get with your engine builder and find out what pistons he used. Those heads are closed chamber heads and typically result in a pretty high compression ratio on a 454. You will probably have to run at least premium fuel. Make certain so you dont run into detonation issues.
Platinum Member
07-16-2020, 08:35 PM
#23
Originally Posted by BillK
Wow,
Those are old heads. 1967-1972 If you get plugs for a 1970 Chevy truck 402 they should be ok. Although I have built plenty of marine engines I have never really used a "Marine" spark plug. Typically use an NGK plug that fits the engine. Looks like NGK YR5 is the oem replacement ? Or an AC Delco R44T should work fine too. Those are gasketed short reach plugs probably like the one you bought to try. There might be a marine equivalent.
The other thing is you probably should get with your engine builder and find out what pistons he used. Those heads are closed chamber heads and typically result in a pretty high compression ratio on a 454. You will probably have to run at least premium fuel. Make certain so you dont run into detonation issues.
Those are old heads. 1967-1972 If you get plugs for a 1970 Chevy truck 402 they should be ok. Although I have built plenty of marine engines I have never really used a "Marine" spark plug. Typically use an NGK plug that fits the engine. Looks like NGK YR5 is the oem replacement ? Or an AC Delco R44T should work fine too. Those are gasketed short reach plugs probably like the one you bought to try. There might be a marine equivalent.
The other thing is you probably should get with your engine builder and find out what pistons he used. Those heads are closed chamber heads and typically result in a pretty high compression ratio on a 454. You will probably have to run at least premium fuel. Make certain so you dont run into detonation issues.
