Rover exhaust thread repair

[ratwing]

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.

[Ian Anderson]

I would expect a helicoil is the way to go

Ian

[stevieturbo]

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

[ratwing]

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.

[Blown v8]

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

[ratwing]

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???

[stevieturbo]

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