Can anyone tell me if the 428 cobra jet heads and the 390 fe heads are interchangeable as far as headers go? Posted using the Full Custom H.A.M.B. App!
Depends on the bolt pattern. Standard FE's had the 8 bolt vertical pattern. Engines used in Mustangs and Fairlanes also had a diagonal pattern, as the bottom bolts are inaccessible in the tight engine compartment. 390 GT heads had 14 holes for the diagonal plus top holes. 428CJ and SCJ heads should have a 16 hole dual pattern that works with either. Regular 428 heads have the standard vertical pattern.
Headers should interchange, however, you "might" have to slightly deepen the slot on the outer, upper bolt holes if using 390GT heads, as the outermost, upper bolt holes are slightly lower than other FE heads (something like 1/8"). Otherwise, should be no issues.
Thank you guys very much. I was racking my brain trying to find something that would work. Posted using the Full Custom H.A.M.B. App!
As stated in above , you can slot the header flange on the passenger rear cylinder. If you eaver plan on running exh manifolds , that won't work. If you have 428CJ heads the casting number between the center cyls should be C8OE-6090-N if my memory is right
You also have to be careful about the port location too- the later heads like C8AE's and D2TE's have the ports lower in the head, so even if they bolt up, they may not match right and may leak pretty good. As far as CJ's, they are basically a low riser type head with smog ports added, so the ports on any of the early heads match, like the C1's and C4's, which are nearly the same as LR's but with standard size valves. There were a few upgrades/ changes in port and chamber size and shape, some small chambers and such, but basically if you take a set of C1's or C4's and add the 2.09/1.65 valves, you will have the functional equivalent of a LR or CJ head- except there are no bosses cast in to add the extra exhaust bolt holes if needed. Isn't a big deal on a shock tower car with headers, as it's easier with headers to bolt up the upper and lower bolts anyway- you can get to the lowers from under the car. With the stock cast manifolds, you need the cross pattern
You guys rock. Thank you for the wealth of information. I have a 72 390 with 428cj heads in a 54 f100 with mustang II IFS and it has been a challenge finding headers/manifolds that would work for me. But I finally found some I just needed some more details on the differences. Thank you all again. Posted using the Full Custom H.A.M.B. App!
early 8 bolt factory 406 HP "shorty" cast headers will work with cj heads and can usually be had for around 300-500 set - the 427 long branch style would bolt up to but chassis clearance might be a problem - and the cost 1000-1200...I'm using later model hedman 2wd pickup headers on my '60
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