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JWL · 04-19-2015, 06:42 AM

I have found caps from other engines to perfectly align with the block in my hands. Maybe you will be lucky and no machining will be necessary?

If the new caps require align bore and hone you will need to find someone with the knowledge and experience to cut the clamping face of the caps. I have a special fixture for the lathe which I think I pictured in my book for everyone to see. But, it could also be done in a milling machine with very careful attention to detail. The amount to be machined from the face is usually only about .005 but some shops are accustomed to removing much more and that should be avoided. In some shops they think it is best to machine the pan surface of the block rather than the caps. If it is a matter of only a few thousands to allow for align honing I might not raise objection to that method. However, it has been my experience the normal situation is to lay the block on the table of the machine and begin cutting. Often it requires .020 or more just to get the pan deck parallel with the intake manifold deck. In other words there should be an aligning and shimming operation performed with a dial indicator before any cutting is done. Again, best to deal with a Flathead experienced shop and/or be certain it is even necessary.

04-19-2015, 06:42 AM	#4
JWL Member Emeritus Join Date: May 2010 Location: Fitzgerald, Georgia Posts: 2,204	Re: flathead line bore I have found caps from other engines to perfectly align with the block in my hands. Maybe you will be lucky and no machining will be necessary? If the new caps require align bore and hone you will need to find someone with the knowledge and experience to cut the clamping face of the caps. I have a special fixture for the lathe which I think I pictured in my book for everyone to see. But, it could also be done in a milling machine with very careful attention to detail. The amount to be machined from the face is usually only about .005 but some shops are accustomed to removing much more and that should be avoided. In some shops they think it is best to machine the pan surface of the block rather than the caps. If it is a matter of only a few thousands to allow for align honing I might not raise objection to that method. However, it has been my experience the normal situation is to lay the block on the table of the machine and begin cutting. Often it requires .020 or more just to get the pan deck parallel with the intake manifold deck. In other words there should be an aligning and shimming operation performed with a dial indicator before any cutting is done. Again, best to deal with a Flathead experienced shop and/or be certain it is even necessary.