I've looked into them alot too, or i've tried but being the 16 bolt exhaust those aren't it i dont believe, the exhaust port is a full 1/4in taller than regular 390 heads
Yep- and the exhaust port location is different on some heads. The only significent difference in the GT heads is the dual bolt pattern on the exhaust- ports & valves are the same as the same year standard head- so if you ever need a few bux, you can sell those to someone restoring a 390 Mustang, Cougar, Fairlane, or Comet, and bolt on a set of verticle bolt-pattern ones, and it'll run just the same. You might want to check that your headers vertically match the port location on your heads- if they're off a bit, you can slot the flanges to get 'em closer
Atleast their gt heads, i figured they were but just wanted to check, so i have another question, i have another set of "gt" heads C7AE-A with 14 bolt exhaust and these exhaust ports are a 1/4in small than the ones previously listed, how can that be if their both 390 gt heads?
i have another set of "gt" heads C7AE-A with 14 bolt exhaust and these exhaust ports are a 1/4 in small than the ones previously listed, how can that be if their both 390 gt heads?
Ford ID Number: C7AE-A = Ford Part Number: C7AZ-6049-A .. Cylinder Head
I would have answered sooner, but I just returned from Hawaii.
Part number source: 1965/72 Ford Passenger Car Parts Catalog.
So technically those heads could be considered 428 heads?? And so than the first set of heads i listed, are those only 390 gt heads or were they ever used on the cobra jet since they are 16 bolt exhaust? And thats fine, hope you had a good time there!
I still dont know why guys get all gitty over the GT and CJ heads ? a Good ported set of C4's will out flow them anyday ! and better than out of the box edelbrocks !
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So technically those heads could be considered 428 heads?? And so than the first set of heads i listed, are those only 390 gt heads or were they ever used on the cobra jet since they are 16 bolt exhaust? And thats fine, hope you had a good time there!
You're making way too much fuss over these heads- the GT heads just have the extra bolt holes because of the difficulty bolting up manifolds in a shock-tower car with a verticle bolt pattern- same reason the CJ's do- don't perform any different than the regular 390 heads of the same vintage. You have heads that will work quite well for a "torque" pickup engine- which is what you have. Quit worrying about what "some people" say about this head and that head and just drive the critter- the heads you have are fine. They are NOT CJ heads- and you don't NEED CJ heads for a 4x4 engine
You're making way too much fuss over these heads- the GT heads just have the extra bolt holes because of the difficulty bolting up manifolds in a shock-tower car with a verticle bolt pattern- same reason the CJ's do- don't perform any different than the regular 390 heads of the same vintage. You have heads that will work quite well for a "torque" pickup engine- which is what you have. Quit worrying about what "some people" say about this head and that head and just drive the critter- the heads you have are fine. They are NOT CJ heads- and you don't NEED CJ heads for a 4x4 engine
There is no way on this earth that the real CJ heads will not out preform, especially at the big end, the standard heads of the same year. The ports, both intake and exhaust are a lot larger, like the pre-1966 heads ports were bigger. In 1966 the move was made to smaller ports because of improved performance and mileage at lower RPM because of high velocities thru the ports for the standard grocery getters.
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You're making way too much fuss over these heads- the GT heads just have the extra bolt holes because of the difficulty bolting up manifolds in a shock-tower car with a verticle bolt pattern- same reason the CJ's do- don't perform any different than the regular 390 heads of the same vintage. You have heads that will work quite well for a "torque" pickup engine- which is what you have. Quit worrying about what "some people" say about this head and that head and just drive the critter- the heads you have are fine. They are NOT CJ heads- and you don't NEED CJ heads for a 4x4 engine
Sorry i'm just trying to clarify everything and get all the little details right, and yes CJ heads will out perform regular stock 390 heads, that's kind of the reason "special" heads were made for the cobra jet, otherwise just anyone can tap holes in heads and call them CJ or GT heads, the valves flow better and the intake and exhaust ports are so much larger so how wouldn't they out perform??? And why not need em on a 4x4 truck? I like speed and horsepower, my trucks not for only offroad and i like to race in town. I just wanted to clear things up because people outside of this forum have said different things about the two sets of heads.
There is no way on this earth that the real CJ heads will not out preform, especially at the big end, the standard heads of the same year. The ports, both intake and exhaust are a lot larger, like the pre-1966 heads ports were bigger. In 1966 the move was made to smaller ports because of improved performance and mileage at lower RPM because of high velocities thru the ports for the standard grocery getters.
Actually the CJ's are basically just low-risers with extra bolt holes- not "special" heads- even the valves still have vestigal nubs in the center, not as large, but like the ones that were to work with the bumper top '63-'64-'65 low risers. The CJ was basically early low-riser heads, a 390GT juice cam, PI/low riser rods, and an improved cast iron version of the aluminum PI intake- a very strong, inexpensive engine built from existing parts on a 428 production block, by Bob Tasca, and put into production by Ford. And low riser ports (and chamber) are pretty close if not the same as the plain C4AE heads, just larger valves. You can build the functional equivalent of a CJ head by installing the larger valves in a plain C4AE head- just won't have the extra bolt holes. The later small (high) port heads follow the medium riser port style, since the lower part of the port doesn't move much air anyway, and the velocity improved with the smaller cross-section- ever looked at a set of MR's? You'll see that smaller, high port just like the later plain-jane heads. Yes, CJ's will outperform on top, especially with larger size engines- and the smaller-valve heads will be more torquey down low- like in a 4x4 engine. I have run both on the same 427 in a highrider, the plain C4AE heads had awesome torque and throttle response down low, and with the CJ's it started to really run good around 3500, with less low-end than the C4AE's. If you were to look at the ports in a stock iron CJ intake manifold, you would also find the smaller, higher port like a medium riser- and it works just fine with the downstream mismatch in the CJ heads, as the low part of the port is pretty much dead air anyway. This stuff is all pretty common knowledge amongst folks with 427 and CJ experience, not something I thought up. Do a little research on the serious FE car forums and you'll find the same info. BTW, the Streetmasters, Street Dominators and such also have the high, smaller port design, and will also work just fine with the older, tall-port heads, as well as the newer heads that "match" that port size
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heads C7AE-A with 14 bolt exhaust and these exhaust ports are a 1/4 in small than the ones previously listed, how can that be if their both 390 gt heads?
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