2 different types of 427 J Heads?


i do compared J-Codes heads (C8AE-6090-J) and found 2 different Exhaust bolt pattern?

Please see the Pict.

I do have both, 1. row and 2nd row.

I am pretty sure 2nd is GT-E since they are fitting the exhaust headers.

But wondering what the other heads are for? (Both do have C8AE-6090-J #)

Thank you


What are the date codes on the heads, from top to bottom? I’ve never seen a set of J code heads with only vertical exhaust manifold bolt holes before.

I owned a set of J code heads that had only the vertical 8 bolt pattern. I bought them from a guy in El Paso, TX who had ordered a set of replacement heads for his '64 427 Galaxie from his local Ford dealer in 1968. They were a 7M date code.

Here’s a picture of them after I had them drilled for 16 bolt pattern:

i mean thes 2 types:


Date Codes of these in picure up: 7H…

down are: 7I… and 7M…

Differece is the very outer top hole


You have one listed as 7I…, that must be a mistake, because Ford didn’t use the letter I because it was too much like the # 1. Check again.

its maybe a J ?


Here you can see the different heights of the upper holes.
When Royce cylinder heads are the holes in line.


Ford likely drilled and tapped those holes for two different exhaust patterns.

The GT-E used the regular 390 exhaust manifolds and the first Mustang Cobra Jets used 428CJ exhaust manifolds.

These heads were used on the ‘135’ R code Mustangs too.

Hopefully Sportyworty will come along and confirm?

Do i understand right, Ford use 428CJ cast Exhaust Headers
on 427 Engines too?

No, they didn’t. But they did run out of 427 J code heads during production and switched to the 6090 - N heads, but with only 14 exhaust bolt holes drilled (ala 390). Slightly later (April 1, 1968 to be exact) when 428 production started they used 428 exhaust manifolds on the 6090 - N heads. Hope this helps.

Sorry, my reply didn’t make sense. The -J cylinder heads were also used on the first 50 Mustang 428 Cobra Jets, which were special built in December 1967 (I believe).

That is right Scott. The “135” cars were built with the 14 bolt J heads utilizing the 390 GT exhaust manifolds.

But Nobody explains to me why Ford make 2 different C8AE -J Heads
with different pattern of TOP exhaust holes?

Thank you in advance


The heads with just 2 vertical holes per port are service heads. These are considered low riser 427 heads and this later J casting served as a service part for earlier built 63-65 pre medium riser 427 cars. They were never offered on a production car with that exhaust bolt pattern. I believe the very rare late in 67 W code Fairlanes used the J head as well but would have also used the diagonal 390GT exhaust pattern and manifolds.

The basic answer is you have over the counter service heads from a Ford parts department. There will be no partial vin stamped on the end. They can be drilled for 14 390 GT manifolds or even 16 428 CJ as Royce shared in a previous post.

Because the Cougar GT-E 427 used the 14 bolt pattern it had the bolt holes drilled lower on two top holes to match the 390GT / 427 GT-E / 428 GT500 exhaust manifolds.

Jim, On the 427 cars built after April 1 68, what heads and manifolds should have been on them, because as stated above they ran out of J heads, does this mean that when they started using N heads, and also used CJ 2 1/4 manifolds and exhaust ?

interessting question ! :stuck_out_tongue:

They used an N CJ head with 14 bolt 390 GT Manifolds. The only cars that got CJ 16 bolt Head/exhaust were CJ 428 cars

Well, it looks like I am going to have to sell my J heads and buy some N heads with early 68 date code, which means I will be competing with the early CJ guys $$$$$

The N heads on my 14C built 427 GT-E are dated 8B2, fyi.