Cylinder heads

[76-cj7]

Ok......im not much of an AMC guru but when i bought a 76' cj-7 it had a t-18 with a 304 thats was supposed to be "radical" as the P.O. had stated.....not! The heads were junk, the bottom end had .040 bearings when it was stock size which grooved the crank so bad it had to be taken to .020 . The oil pump housing was so bad i had to buy another one which i got from Bulltear :mrgreen: . The dist gears were toast and not to mention it had a Summit cam with 3 less lobes than it should 111!!! I know its crazy isn't it? haha But ne ways he gave me another set of heads that he for some reason he had lying around but i took em to the local machine shop and had em tore down to verify if they were good or not so they came back A ok and i installed new Crane valve springs and seals but i have them installed on my motor and as i just finished painting it i noticed that just the two inner exhaust ports have 3/8 threads and the outer two have what looks like 1/4 threads????? The other set of heads had 3/8 all the way around so i never thought twice to check. Number 3, 5, 4, 6 have 3/8 threads but 1, 2, 7, 8 have smaller......Why?!?! Can somebody explain if and why they are like that? Are these special heads or shitty?

[76-cj7]

Oh and im trying to find the casting numbers to find out what they are and i cant seem to find them. On the front of the head?

[jeepsr4ever]

The casting numbers are on the top of the head under the valve covers. If you do a search here under "head casting numbers" you will find Pyagid's casting number reference chart. You need to be carefull when running later model heads (with 3/8-16 bolts and 5/16-18 bolts) because they might be for the larger bore motors (360-401) and the valves will hit the sides of your cylinder wall...some notching may be required. that is if they are for the 360 or 401 (dogleg exhaust ports). If they are 304 heads then you can bolt them in place of your own heads or keep them for a easy swap later.

[76-cj7]

They are the 79-81 heads with numbers 3233324-2 so i guess they'll work just fine! But whats with the 5/16" threads? Any things special about them? or just a low performance head?

[jeepsr4ever]

No, they changed the outer bolts to that size I believe in 1975

[76-cj7]

I ended up just tapping them out to 3/8" so its all good now! :?

[Goose]

Yea those odd size bolts will kick yer butt if you dont realize it, and are trying to put the big bolts in the little holes while holding the headers up there ..and holding your mouth just so.. with yer toungue sticking out the side saying "Aw fer cryin out loud !! could they have possibly made any less freaking room fer these @#$#@@##$$%%#$#@@ bolts.. then you drop the bolt...into the hole in the crossmember, twice!

[76-cj7]

HaHa So very true! :(: