what size bolt on the back of the head

[Jkstang78]

I need to put a bolt in the back of the head for the exhaust cross over. The pipe that goes to the H-pipe I think it is. Need to know size of bolt and thread size.

 

[the pony boy]

i used a spark plug with the top snapped off. good luck phil

 

[Jkstang78]

Oh crap that is right those do fit thanks man. I forgot all about the trick.

 

[89MustangGX]

I believe spark plugs are actually the wrong size, but all the carbon makes them seem ok. Correct size is 5/8-11 IIRC.

 

[Black 93 Fox]

It is a 5/8 11 course thread. Make sure to put some thread sealer on it.