need help with 401 head choice 1971 or 1974

skyhookdutch

i bought a 74 401 from a jeep cheif and it has 2 different heads on it, one has bridge rockers, the other has single rockers with rocker studs?i looked up the head cast numbers and one comes up as a 74 and the other comes up as a early 1971's, 2 types evidently for that year early and late model, well i have located a 2nd 401 engine complete except intake and it has the matching pair of early model 1970 heads on it, are these heads worth running or try to located a match to the 74 head i already have, i do know there is a good bit of differnce in the 71 and 74 as far as cc''s are concerned, also are the amc 360 heads the same from a late model 360 with bridge rockers,ok here are the numbers please correct me if i am wrong driver side head 319629 1 c and the passanger side head 3220502-1 these numbers show the 319 is the early 1971 with 50.60 cc's and the 322 is the 1974 head with 57.92 cc's and yes this motor was a complete runner, how i have no idea as all the info i can find about these heads say the 71 needs bolt holes filed down on the intake and the head bolts are different sizes??????

pyagid

yes according to your numbers you are correct about the years. Any 360 heads from late 71 and up will be the same as you 74 head.

You could look at the chart here for the reference numbers
http://www.bulltear.com/forum/viewtopic.php?t=541

i would be curious about the running condition as well. Were the holes enlarged? for bigger head bolts to fit 111!!!

-paul

73hornut

I would run the matched set of the later heads, to keep compression down for pump gas.

tufcj

If you ever plan on a buildup with roller rockers, find a set of the non-bridged heads. If it really doesn't matter, then the bridged heads 360-401 are all the same from 74 all the way to the end of production. If you decide not to use the 3196291-C head, I'll make you a fair offer on it. I bought a pair a while back, but one was cracked and un-reapirable, so I have a single sitting on the shelf (not for sale). Bob tufcj

jeepsr4ever

Running different compression in any one or number of cylinders will cause major vibration at higher rpms. Some engines had a overbored cylinder that was caused by either core shift when cast or resetting the tool and screwing the first cylinder up at the engine plant. These engines were replacements for warrantee and used as left over engines for special cases. Your engine is not one of these and was probly throw together with parts left over in someones garage or parts from a bone-yard. Either case you should have the right compression in all cylinders. Without the equal compression bearing damage will occur.

skyhookdutch

well thanks for all the info guys, as far as i can tell the 71 head was a replacement, it had tell tale signs, newer valley pan and blue goo! as for the 71 head shoot me an offer for the head as i most likely won't need it, i have located another 401 with matching heads from 1971 that is complete so why have 3 heads......... so if i take my 1974 block which is being freshed up stock bore (deglazed) new standard pistons and rings, cranks been turned under, thrust bearing area on the crank has been rewelded and ground to spec. block has been total checked out for trueness, cam? what cam should be run in this motor can anybody offer up a suggestion? and if i do run the early 1971 heads will my compression be so high that it will cause problems , pump gas, detonation!!!!

Gremlin4ever

skyhookdutch wrote
new standard pistons and rings

I for one don't see a problem with the closed chambered heads. You'll love the added power output and it should run just fine on pump gas. The '74 should've had a much lower compression due to emission controls of the time, so the compression should still be under 10:1 which would still run on 93 octain. The earlyer heads are the best offerings from AMC and everyone wants a pair because of this. The flow very well. As for you Cam choices, call a cam company and describe your engine and vehicle and it's intended use, they'll tell you exactly what to put in it.