broken exh.man bolt

[Duncan1]

Anybody have a good how-to-source for fixing broken exhaust manifold bolts on the LT1? Thanks

[bobss396]

Can you grab any part of it? If so, buy or borrow a stud extractor. Sears used to carry them. Hit it with WD40 or some other penetrating spray, a Bernzomatic torch helps to break the rust bond. If not, it's go fish. You'll have to drill out the busted stud and re-tap the manifold.

If possible to reach, grind or file the stub flush with the manifold. Use a good center punch and make a center mark. Do it light at first, you can chase it over if it's off a bit.

Next, drill the stud with a small drill like 1/8". If you feel real brave, try to get the stub to turn using a left-hand easy out, you may have to drill a bigger hole. Heating up the manifold with a torch will help. But if you break the easy out you'll probably have to pull the manifold and replace it or go to a real machine shop with it.

If you don't feel so brave try to drill & re tap it. Work up to the tap drill size in a few steps, keep it as straight as possible. You can find the tap drill size online or ask me if you know what the stud size is. Hopefully you'll have the room to drill and work a tap wrench.

Bob

[57chevyragtop]

Originally Posted by Duncan1

Anybody have a good how-to-source for fixing broken exhaust manifold bolts on the LT1? Thanks

Good advice in above reply. You may also try using the corner af a small sharp chisel at the edge of the broken piece tapping it with a hammer...Sometimes the broken piece will work out easier than you think once the torque of the bolt head/nut has broken. This has worked for me more often than not over the years working on 283's 327's 305's etc. Let us know if you get them (you stated bolts) worked out.

[Duncan1]

Well, thanks guys.
The bolts broke off flush with the block and we can't get any drill bit to have any effect on the bolts. We bought the most expensive bits for hardened steel and the bolts seem to laugh at us. We have now started welding one spot on top of the other onto the bolts so we can grab on to something and number 1 came loose. Then we had to stop for the night. We'll see how it goes today. Thanks again.

Update:
Welding onto the broken off bolts is the way to go if they're broken flush with the block. Car is back together and running fine!