Stripped the bolt-hole for the coolant crossover bolt. The bolt is not anything normal. Not any 14mm or 12mm, not 1/2". Maybe 13mm, but can't seem to find that size tap.

 

It's a special thread (1/4-18 NPSF) dryseal, straight pipe thread. Can't see how you would be able to fix it with the head on the car.

 

the LT1 is in a thirdgen, i might be able to get a tap in there

 

Still, you are going to have to helicoil it or use other thread repair. Running a tap of the same size in a stripped hole isn't going to fix it.

 

that could suck then. I'll try the tap first though and also look into thread repair like you mentioned. Thanks for the advice, at least now I have an idea of what I have to do to fix this.

 

if it's not too bad you could run a thread chaser....or a tap...through to clean the threads. then when installing a bolt if there's oil/coolant you could apply some thread tape.

 

Ok, I'll pick up some thread tape too.

Another question...Is there a common-name store(like home depot) that would carry this odd size tap or would I have to order it from somewhere.

 

I used a 1/4" NPT tap on mine. Just dont go too far since its tapered. Taping the threads with thread tape wont help since they dont seal. All the bolt does is hold the sealing washers in place and let coolant pass through to the tube.

If its too bad, It would probably be easier to just tap both heads to 1/4" NPT, put in pipe fittings with 90* hose barbs, and just run rubber hose with a T to connect them and then go to the radiator. I think you would have a very hard time finding that thread in a heli coil.