Why do Flathead V8 Blocks Crack?

[Henry Floored]

Originally Posted by Johnnydidd

Flathead design has caused the cracking, very poor design. If you have flathead you will have the problem sooner or later. Block repair is a good answer, I had one repaired few years ago no problem(cracked from no 2 cylinder to valve seat). My recommendation keep as cool as possible, I am always looking for ways to keep engine cooler. I have a Model A that has been overheated to where it would hardly run no cracking, but look how the exhaust valve is next to the manifold.

Any cast part is subject to cracking. That is from any manufacturer. Even the much vaunted small block Chevy can acquire cracks.

The Flathead Ford can get cracked in one of three ways usually. One by freezing. Two by over tightening of the too large diameter head bolts. (the Flathead Ford would be better off with 7/16" "torque to yield" stretch bolts, there is simply too much ability to distort and yes crack the deck with the factory fasteners). Third is probably steam pockets as one other gentleman has mentioned, though that is an educated guess on my part. The Flathead block is a complicated casting and as such is quite a technical triumph to be as good as it is. It would be a strong challenge even for today's pattern makers and foundry men to try to duplicate it today.

When you comment that the Flathead is a "very poor design" I have to take issue a little bit sir. I think you might be referring to the internal exhaust porting. While yes that is unique to the Ford Flathead they do not constitute poor design. On the contrary, the exhaust porting was a no compromise solution to the problem of packaging and plumbing.

The Caddys and LaSalles ran exhaust out the top and it's very "busy" on the top of the engine. Intake and exhaust manifolds fighting for the same space.

Pick your poison I guess but the Ford solution is not a poor design in my humble opinion.