Header pipe studs

[dbeardslee]

Does anyone know the correct length for header pipe studs? My F model is developing issues with steel bolts in aluminum housings, so I'm thinkin' I'll get rid of them, repair the damaged threads and put some locktited stainless steel studs in their place. Trying to avoid multiple trips to the hardware store, although it seems like I'm there every day anyway

[Mathh]

Thanks to Miti from the UK forum, there are two types :

part# 95611-08625-00;
Internal thread - 16 mm long , external thread - 18 mm long, overall length - 41 mm (centre shank - 7 mm)

part# 95621-08615-00 (same as 3H3);
Internal thread - 15 mm long, external thread - 12 mm long, overall length - 31 mm (centre shank - 4 mm)

[dbeardslee]

Math - you da man. Thanks

[DiverRay]

The Standard uses the LONGER studs. If you have an aftermarket exhaust system, the shorter stud may work.
Chevy uses the same size studs on the newer smallblocks, so you CAN pick up a kit from the parts store, with the BRONZE bolts that hold and don't stick to the stud.

[dbeardslee]

Ray - Thanks for the reply. The longer ones it is.

The F models have a little lip that goes around the inside edge where the header pipe flange goes in. On mine some previous P.O. evidently didn't bother getting the pipes lined up correctly before tightening them in place, and crushed the lip on all four cylinders. Consequently, it wouldn't let the pipe go back in as far as it should and required a lot more torque on the bolts to get a good seal. As the pipe wasn't back far enough, all the torque was on the end of the threads, with predictable results.

I noticed on my brothers 80 that it doesn't have the lip. This weekend I'm taking the header off, and I'm going to grind the lip off and install studs. Should get a better seal that way and the pipes should go back to where they're supposed to. I was going to use the nice chrome hardware they have at ACE. You can never have too much shiny stuff

[dbeardslee]

Yesterday was interesting. What I thought was a lip was in actual fact million-year-old muffler gaskets that looked for the world like they part of the head. Somewhere up the line somebody decided to double-up the gaskets, and as I had already dug four old ones out I didn't catch it. I started grinding on 'em and I could tell by the way they were coming apart, something was amiss. Used a screwdriver and some picks to get 'em out - wasn't easy. Then the real fun began.

5 of the 8 bolts on my headers decided that was the last time they would function in the illuminum - they stripped completely. Thank god for helicoil - or in my case permacoil (which is pretty close to exactly the same thing.) I drilled and tapped the 5 offenders. A couple of the inside holes were tricky, and I had to remove the motor mounts and drop the engine as far as it would go to access.

I love the permacoil product, but there are a couple things you should be aware of if you use them. First the hole has to be VERY well tapped. After you get the tap through, you need to do it several more times until you can turn the tap with your fingers. Any little burrs in the threads can cause the coil to catch on the way in, and that can cause the little tab to break off. As long as you still have something sticking out of the hole, you can get 'em back out with needle-nose pliers but it destroys the insert. On the last three, as I was perfecting my technique, I found that a little shot of WD-40 in the hole and a little on the insert makes them go in much easier.

Ray - I think you're right about shorter studs working on aftermarket pipes - at least in my case. After getting the permacoils in place, however, I may just stick with the bolts. Now I have steel-on-steel contact, so wear shouldn't be the problem it was. Not to mention the fact that those darn automotive studs are $2.50 ea. at my local ACE. Additionally the hex-drive bolts I currently have give it a better look.