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Posted: 03/18/10
07:11 AM
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I hope this helps anyone who is looking to identify a AMC Head Casting Number.
THE BACKGROUND: The vehicle is a 1977 Jeep CJ5 w/304 (verified by the "304" stamped in the underside of the block), performer intake, carter 4bbl, DUI HEI, Hooker Headers & KN Air. I bought it in 1987 and am the 2nd owner. I recently found an outstanding deal on a set of 1980 304 heads that had been decked, new valves, springs tested, cleaned & painted by a performance race shop here in Phoenix. Knowing that my Jeep was due for a valve job I decided to bite the bullet, rationalize it to my wife, and then made the purchase. Once the old heads were off the block and we compared the new & the old, there was no comparison, it was like night & day. Not one of my Jeep manuals showed 304 heads with a studded rocker arm set-up. Needless to say the studs did not fit the 1980 heads, and I had to buy 8 sets of the paired fulcrum rocker arm setups, and they installed nicely and my 304 runs better now than it ever has.
MY QUANDRY: I have been going crazy trying to figure out what they are and where they came from. Nobody seemed to have any idea just what I had, I'm sure they thought I was some type of joker. The casting number is 3212990-4, now this number comes close to "the mid-70 to mid-73 58cc heads casting number 321-2993" But since it is not exact I can not be 100% sure of what I have. I would like to sell these heads to recoup some of my project costs and need to be sure.
THE SEARCH: Began with this forum where I was given a website to visit: (http://www.planethoustonamx.com/main/prepping_amc_v.htm) where I found some info, but not the casting number of my old heads, which was as follows:
"Prepping AMC V-8 Heads For Performance Use
There are 2 desirable subtypes of AMC V8 heads. The 1970 to early-71 heads with 51cc chambers (casting number 319-6291), and the mid-70 to mid-73 58cc heads (casting numbers 321-2993 and 321-3948). Both heads have the superior dogleg exhaust port and studded rocker arm mounts. The only real difference between them is a thicker layer of metal inside the combustion chambers. When you compare the two side by side it is very noticeable, especially between the valves."
"(Later heads are identical to the 58cc heads except for the paired fulcrum rocker arm setup, which is not adjustable in any way, and requires quite a bit of machine work to convert to an adjustable drivetrain. However, the later heads flow just as well as the earlier ones if you are willing to spend the money to convert them. There are rumours of some kits that help do this.)"
"Both of these heads were original equipment on 4V 360s, 390s and 401s. Before porting they outflow almost all other small block heads, and with porting they are still competitive with some of the best out there until you move up to aluminum race heads. The design is a product of the factory Trans Am racing effort in the late 60's, and culminated in the winning of the Trans Am Championship in 1972 and 1973." I wrote the author and asked if he had any further info and he referred me to http://www.jedi.com/obiwan/jeep/wagoneer/401/pics/amc-v8-heads.jpg where I finally found what I was looking for.
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Dirty Deeds DunderJeep 77 CJ5 304
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