73 Bronco head

[larryejoh]

I have a 73 Bronco with a 200. The old head that was on it (C9DE 6090-M) has worn valve guides and needs 6 new valves. My machine shop has a head that that they did and the owner did not claim that has all new guides and valves for $211. This head has a C6DE 6090-B casting number. The question I have is that the C6 head is noticeably thinner than my head. The machinist measured the head and it is .100 thinner than mine. I believe this head is a 52cc head and with this much milled off my compression would be too high. I also found a E0BE-6090-B in a 82 Fairmont for $32.00. Should I rebuild my old head which will cost $245 with the 6 new valves and guides or try the E0BE-6090-B head which have the added benefit of larger intake valves and harden seats?

 

[Anonymous]

Larry -

The C6 head would actually provide a compression ratio of about 8.5:1 with a composite head gasket. Those heads had small chambers from the factory, but used a thin steel-shim gasket and mantained a CR of 9:1. The problem with this head is that the intake is much more restrictive than the C9 and later heads, and there's not a whole lot you can do about it. Avoid buying that head if possible.

Although I really doubt the C9 head you have on your 200 now is the original, I would rebuild it. You can add the larger valves and hardened seats then. The C9 heads originally had chambers that were significatly larger (62ccs) than previous heads as these were introduced for the 250 engine. Your CR is down way low right now - about 7.6:1

So... I would have it milled - down to about 48ccs. With a Fel-Pro composite gasket, you would then be sitting around 9:1 CR.... assuming you are using stock dished pistons and haven't milled the deck of the block.

 

[CZLN6]

Howdy:

The C9 head John is referring to has an "M" suffix after the second set of 4 digits. The earlier C9 heads are very comparable to previous heads.

I'd go for choice three- the EO head. It will have to be milled to accomodate for the larger chamber and the composite head gasket, but it will have large valves, the largest intake tract volume, a 1.75 carb hole, hardened seats. Add a three angle valve job and you'll be lovin' it.

Adios, David