Spark Plug seating and types
Thread Starter
Instructor
Joined: Jul 2009
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Spark Plug seating and types
Hi Guys, can anyone help a Brit with a 72 Corvette. The engine is not original, the spark plugs fitted are R43S and need to be changed. The R43S has a sealing ring as opposed to the conical type like R44TS which is what I have seen specified for 1972. Are these different sealing types interchangable or must I stick with R43S with sealing ring? I have read a post here where a member said the R43S thread was also different to the R44TS. Appreciate any help. Cheers Greg
Le Mans Master
Joined: Aug 2006
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
The 'T' stands for 'tapered seat' which would fit the original heads, since your engine has been upgraded the original plugs will not seal without the 'sealing ring'.
Look where the plugs seat in the head, if flat you nead the seal if tapered you need a tapered plug.
Look where the plugs seat in the head, if flat you nead the seal if tapered you need a tapered plug.
Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
Hi Guys, can anyone help a Brit with a 72 Corvette. The engine is not original, the spark plugs fitted are R43S and need to be changed. The R43S has a sealing ring as opposed to the conical type like R44TS which is what I have seen specified for 1972. Are these different sealing types interchangable or must I stick with R43S with sealing ring? I have read a post here where a member said the R43S thread was also different to the R44TS. Appreciate any help. Cheers Greg
It sounds like the original cylinder heads got pulled off and replaced with earlier heads that use the crush washer style of spark plugs. Use your middle finger to probe into the spark plug hole to see if it has a flat bottom or take a close-up picture to see if it has a flat bottom. If so the heads will use the crush washer style of plugs.
Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
Right after I bought my '68 with it's 454" engine I pulled the spark plugs out and found their gaskets had all stuck to the head. The previous owner had put a set of gasket-type spark plugs into heads that had tapered seats!
Melting Slicks
Joined: Mar 2008
Posts: 2,989
Likes: 198
From: Meriden CT
He must have been a candy wrapper machine engineer.
Melting Slicks
Joined: Mar 2008
Posts: 2,989
Likes: 198
From: Meriden CT
Hi Guys, can anyone help a Brit with a 72 Corvette. The engine is not original, the spark plugs fitted are R43S and need to be changed. The R43S has a sealing ring as opposed to the conical type like R44TS which is what I have seen specified for 1972. Are these different sealing types interchangable or must I stick with R43S with sealing ring? I have read a post here where a member said the R43S thread was also different to the R44TS. Appreciate any help. Cheers Greg
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Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
Yep, an R45-S would be the best heat range for a daily driver. If you can find an equivalent platinum plug it'll last about 10 times as long.