Longer spark plugs ok?
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Instructor
Joined: Jul 2017
Posts: 217
Likes: 21
Longer spark plugs ok?
I'm replacing the spark plugs on the 81 vette I just bought. I don't know much about the engine in it yet but it's supposed to be a 383. I know it's not the original engine since the dip stick is on the driver side on this one and it's always on the passenger side on 81s. I pulled a plug out and it's shorter than the ones I bought. The one that came out is a NGK YR5 and the ones I got are NGK FR5. Is there any danger of the piston hitting the new plug?
Old plug: https://www.jegs.com/i/NGK-Spark-Plugs/739/YR5/10002/-1
New plug: https://www.jegs.com/i/NGK-Spark-Plugs/739/FR5/10002/-1
Old plug: https://www.jegs.com/i/NGK-Spark-Plugs/739/YR5/10002/-1
New plug: https://www.jegs.com/i/NGK-Spark-Plugs/739/FR5/10002/-1
Safety Car
Joined: Oct 2004
Posts: 3,927
Likes: 740
From: Youngstown Ohio
Which heads do you have? The specs should list the spark plug threads and reach. That being said, I would use plugs equal to the reach of the old plugs, since they fit and work OK. Do not use the longer reach plugs you bought without knowing the head specs and requirements.
