Hey guys, how do I clean the threads in the block for the cylinder head bolts?

Thanks.

 

I was always told use the right size tap, and oil to lubricate so you dont bust if off. i had that happen on a exhaust manifold and i couldnt drill the tap out so i had to replace the manifold.

 

Don't use a regular tap for chasing the threads, unless they are really heavily damaged. There's a pretty good chance you will cross-thread the tap. Use a 'chasing' or 'cleaning' tap. They will take nicks off threads and get any gunk out, without damaging the existing threads. Some auto parts places have them, and Jeg's and Summit both carry them. Link here to the Jeg's page...

 

speedcat i bet i've done thousands of threads with a thread cutting tap and have never cross threaded a hole. you'd have to really be trying to do it, not know what you're doing, or have damaged threads to start with. the thing about thread chasers is you have to use a wrench on them, i like a tap and tap wrench. there's enough weight with my wrenches that it'll spin on it's own and it makes it easier to do. if you can find wire brush to fit a drill and small enough to go in the hole that works pretty good too. i use wire brush on my bench grinder to clean bolts.

 

Thanks guys for your help.. Once again came through with the goods

I bought a 7/16 tapered Tap, and it worked beautifully.