I'm trying to save a pretty neglected set of CJ heads.

So far we've got them ground flat on all the sealing surfaces, and have all the guides replaced.

The exhaust seats look especially bad, the intakes may be salvagable.


My question to you experts are many :

1. what are the preferred exhaust seats to get? material? brand? source?

2. is it a bad idea to just install all new seats intake and exhaust?

3. what is the recomended interference fit tolerance for exh/int seats?


I have more, but that's enough for now...

the plan is to run all new stainless valves in these heads, springs matched to cam which will be a relatively mild hydraulic grind - something large enough to take advantage of the stroker kit, but small enough to keep the power brakes happy.

John
Milner351@comcast.net

Stellite are best. Intakes don't need it. Installing seats in both is asking for a crack. there's not much meat there.



1912 Model T Ford touring Salmon (ugh!)
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1967 Cougar GT 390 Cardinal Red / Black
1968 Cougar GTE 427 Augusta Green / Saddle
http://www.supermotors.net/vehicles/registry/15029/50071-2

SBI and Snyder both sell good seats, readily available through any parts warehouse. Local machine shop should have 'em. I like the smooth machine finish on the Snyders. S-I seats don't machine well, they are "stringy" when cut with a multi-angle cutter. They grind well though.

Ford sunk a lot of valve jobs right from the factory on the FE's. Lots of times, they are already at the max depth or past, before the first valve job. Exh is easy to correct, as you're installing new seats. Intakes, first try oversize valves, like a 2.15". We use these quite often. But, there are times, especially on CJ heads, that even the 2.15 valve won't help. You either have a sunk valve and have to cut a lot off of the tip of the valve, or you install intake seats. As a last resort, we have installed intake seats on FE heads for years with no problems.
But: you must use sharp, good quality cutters to ensure accurate size seat cuts. AND, you must always install the intake seats FIRST, exh seats second. Heat the heads before install. Two burner plate heater works well. Always measure your seat rings to catch any that are slightly out of spec. Make sure the seat rings are beveled on the outer edge. Any quality ring will be. Have fun.

Rob McQuarie

Thanks for the replies gents - I will forward this information to my friend that owns the machine shop, and we'll do our best from there.

Hopefully we can get away with exhaust seats and oversized intake valves - thankfully - we didn't buy valves yet.

John
Milner351@comcast.net