The Stovebolt Site Forums The Shop Area Engine Shop Is it all right to reuse head bolts?

I kept them organized when I took them off, and they are still organized. I reconditioned the threads in the block with a tap, and the threads on the bolt with a die & cleaned them off. Is it ok to reuse them if they all go back in their original holes?

You don't want to chase threads with a regular tap or die since they often partially recut the threads instead of just cleaning them. A thread chaser is what you need to use. I reused the original bolts on my 38 with no issues but I just wire brushed the bolts. Someone with more knowledge than me will have to advise on reusing bolts that have had a die used on them.

If the bolts got any material removed with the die, and if the block threads lost any metal to the tap, you've got less thread engagement than you had before. Chances are you'll be OK, but don't risk that kind of damage again. Thread chasers have blunted points, so no material is removed in the cleanup process. I use a somewhat dull tap in the block threads, and clean the bolts with a wire wheel on a bench grinder, if purpose-made chasers aren't handy. Use a good anti-sieze compound on assembly, and reduce the torque specification slightly on reassembly. Torque specs in most service manuals are for bolts lubed with 30 weight motor oil. Bolts lubed with Never-Seez or similar high-stress lubes need 5% to 10% less torque to get the same amount of stretch on the bolt.
Jerry

Hy LandonL, As tiny said a thread "chaser" or cleaner is a better choice to clean threads in the block than a tap, you don't actually want to remove any metal, just clean the threads that already exist. The wire brush is a better tool than a die to clean external threads, again you don't actually want to remove any metal.Something a lot of people have never heard of is class of fit, fasteners for different applications have a different class of fit, for example wheel studs and nuts, if they are in good shape they should be snug to install right from the first thread, that is because they have more stringent specifications for fit between the two pieces. Replacing head bolts is a fairly modern practise, all the engines from I believe the 70s and older routinely reused their head bolts. For the old Chevy/GMC engines, I believe there were two different strengths of bolts used, they had different head markings to identify the different bolts

No metal was removed when I used the tap there was so much grease in there. Good thing I guess, I'll never use a tap again. Rookie mistake I suppose.