Spark plug issue

[98 Vette]

Does anyone know why a spark plug would blow right out of the cylinder while driving it other than bad threads on one end or the other?

 

[Rruuff Day]

Does anyone know why a spark plug would blow right out of the cylinder while driving it other than bad threads on one end or the other?

If it wasn't tightened down when installed, it would slowly loosen until it came out. My experience with this was a 351 Windsor I installed in a Ford truck a long time ago. Got it on the road and left for PEI the next day. On the way back from PEI all of a sudden the engine was making a wop wop wop wop noise. I pulled over, popped the hood and here was a plug wire with the plug in it laying off to the side. I screwed the plug back in, checked the rest and drove home. Never had another problem.

 

[Murray20c8]

Something similar happened to me. I'd replace the plug anyway just to be on the safe side..

 

[98 Vette]

Thanks. I did that but it blew out again so I believe it’s a thread problem in the block.

 

[Rruuff Day]

Thanks. I did that but it blew out again so I believe it’s a thread problem in the block.

Yup. Assuming the threads on the plug are ok, it sounds like heli-coil time.

 

[98 Vette]

Yes which sucks. Lol

 

[Rruuff Day]

Yes which sucks. Lol

Or a replaced cylinder head is the only other option.

 

[98 Vette]

Boy I hope not.

 

[Rruuff Day]

Don't blame you.