So I posted on here a few weeks ago, I have a 1995 Camaro LT1,I recently did head gaskets on. When I was reassembling the motor I tore up the threads on the passenger side head steam pipe bolt (banjo bolt). So I wanted to go back to factory being I've already spent money in that direction. But I can not find the thread and size of those bolts. I wanted to have the machine shop drill out the hole and replace with a helicoil. Does anyone know what helicoil I would need?

 

A helicoil would leak. I would go with 1/4 npt fittings. Search for "LT1 steam pipe mod" for pics and how to.
You would need to tap both heads.

 

But from what I’ve gathered it’s like a M13 thread. Slightly bigger than a half. With calipers I got it to .510. So I’m not sure how I would switch to such a small size. There has to be a way to switch without pulling both heads

 

Would a helicoil really leak?

 

Eh, the threads are not what do the sealing. You should have two seals on each side of the banjo bolt therefore if you can put the same kind of torque on heli-threads then it shouldn't leak. I will try and remember to see if I can look it up. I have a manual that gives all the LT1 bolt part numbers and thread sizes, or you can try and look it up to see if it's still on the internet.

 

I already have the new bolts. I spoke to the dealer they couldn’t find the thread. I called the manufacturer that I purchased the bolt from and they didn’t know either. The machine shop said he’d figure it out and make something work so I guess I’m not worried about it now. Now I just have to take my time when putting it back on.

I fully assembled the motor minus minus the steam pipe then discovered my mistake. All gaskets were torqued to spec. Do I really have to replace all of them even tho the motor never fired

 

No. I've reused those rubber seals after being on the engine for a long time. Just as long as they're there and not damaged.

 

Excuse me I wasn’t clear I apologize. Do I have to reuse the head gasket intake and exhaust

 

Out of those I would replace the head gaskets. Once they're compressed, that's it. Intake gaskets I have reused with no issue if the engine has not been restarted. Exhaust I have reused several times after use as long as they aren't blown out. JMO.

 

Cool that’s kind of how I looked at it. Intake and exhaust gaskets aren’t a huge deal to replace. But the head gasket takes some time

 

The bolts are 1/4 NPSF, a straight thread. 1/4 NPT is tapered pipe thread slightly larger than the NPSF, .546". One would think you could run a 1/4 NPT tap while on the car.

 

If you are pulling heads, just swap em, and run a NPT tap thru the messed up ones, plug em and use the other side threads for steam pipe.