Thread: GT 14 hole bolt pattern?

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There are about five postings on ebay claiming GT heads (or not in some cases) with a casting number of C8AE-H. My books tell me that true GT heads are for tht year are C8OE-A or C8OE-B. What isa being sold are standard heads. The confusion is that some have the correct 14 hole pattern for mustangs etc. Was any exhaust manifold for a 390 found on a mustang and several other cars drilled for this pattern whether it was a true GT head?

Rob

Most interchange and parts books list those C8OE-A and B numbers as GT heads. Well in real life they are the engineering numbers found on the C8AE-6090-H FE head blueprints. And yes the 14 bolt C8AE-6090-H are true GT heads. The same ol heads found on all other FE's from late 67 on till the D2 heads came along. Just the bolt pattern makes them correct for the GT application. And those can be drilled if they have a different bolt pattern. My 68 S code Cat's 390 is bone stock with 14 bolt C8-H heads. In fact the whole engine, smog, AC and all is original. And shares quite a few smog and AC parts with the 428CJ applications. As far as the heads having different bolt patterns for other applications I'm not exactly sure. But I'd think the original GT parts were 14 bolt only. All the ones I've had were that were original. And service replacement castings were all 16 bolt to cover all applications exhaust pattern wise. Thus one head fits all applications.



G.

G,

So from what I could see in the specs I have is that GT heads were no different than any other 390 heads with ~68 cc chambers except for the 14 bolt pattern?

I assume then that the 14 bolt pattern was not exclusive to GT heads and could be found on any 390 mustang, cyclone etc. Or was it that these special exhausts were only offered on the GT?


Thanks,

Rob

Correct the heads are the same no matter what the bolt pattern.

Clearance was the main reason they used a diagonal pattern. There was not enough room to install the lower bolts in the 390 Mustangs, Cougars, Comets and Fairlanes. So a new exhaust manifold was used with the diagonal pattern. This allowed the clearance needed between the head and manifold. The exhaust manifolds and heads were the same for the 390 GT or std 390 when used in the cars listed above. I might have missed one or two models. Over the years the heads and manifolds have been "nicknamed" GT heads even tho they were used in non GT versions.


G.

Also to mention when the heads are installed in the Mustang and Cougar it's almost impossible to tell and see what bolt pattern they are. So if your heads are 16 vs 14 you'd have to look up from underneath the car to see if they were drilled or not.