The V8 Owners Forum -

I’ve stripped an exhaust manifold thread in the head and am wondering about what’s the best/least worst way of repairing it. I’ve been using cap head bolts because of clearance problems so it looks like a helicoil is needed or is there a better way?
The engine is uncovered so access is dead easy if it can be done without taking the head off.

I would expect a helicoil is the way to go

Ian

Helicoil definitely the easiest and best option.

Kits are cheap too and always handy to have, and will let you retain your existing thread size.

I think they are 3/8 unc ? Don't recall them being 5/16"

https://www.engineeringsupplies.co.uk/3 ... r-kit.html

Cheers for the replies, I've ordered a 3/8" UNC kit. They look easy enough to use as long as the drill goes in straight so I think I'll knock up a fixture to guide the drill - a thick lump of mild steel with a hole for the drill and a hole to bolt it to the other exhaust port thread should do it.

This is one of the reasons I went to studs instead of bolts

Yes, studs are definitely preferable but there isn’t room to turn nuts or bolt heads on my exhausts hence I’m using cap head bolts.
However I have a cunning plan to make 16 off 3/8” UNC internally threaded tubes the same O/D as the cap heads and screw a cap head into one end so I can do them up on studs.
I haven’t checked yet but I’ve been told there’s a high temperature loctite that works on exhausts, this would keep the studs in the heads and the cap heads in the threaded tubes.
Edit - I don’t know what I’ve done wrong here, the first pic is upside down and the second is sideways???

Looks like you'd have room for a flanged nut maybe ? ie

https://www.westfieldfasteners.co.uk/UN ... nless.html

ALthough stainless vs not is debatable. Stainless can be nice, but a bugger if you drop it and need to use a magnet.

I've been moving back to regular mild steel for a lot of stuff. I dislike allen keys for anything these days. They look nice, but they're just a nightmare if too tight, stuck, access etc