AMC 360 vs AMC 304

I have an AMC 360 that I know needs some work done to the heads and might need an entire rebuild and a friend that has offered to sell me a 304 cheap that "ran before he tore it apart" and I am trying to decide which would be the best to rebuild and put in my '72 cj5.
I am curious if anybody has any idea what the difference would be in rebuild cost, power, and gas mileage between the two?

I have an mc2100 carb and T-15 transmisison.
Also would I have to switch out the bellhousing or any of the drivetrain to hook up the 304 instead of the 360?

The heads can't be swapped between the two can they?

There's no replacement for displacement. All AMC V-8s are based on the same block, from 290 all the way to 401. The 304 and 360 share the same stroke, the 360 has a bigger bore (4.08 vs 3.75). The 360 heads have bigger valves. You can put 304 heads on a 360, but performance will suffer, and with a bigger cam, there may be valve/piston clearance issues. A 360 head won't go on a 304 block, because the intake valve is so big it can hit the cylinder wall when it opens.

If both engines need a total rebuild, go for the 360, cost is nearly identical. If you can just re-gasket the 304, use it temporarily, it's a bolt in. You will need a flywheel specifically for a 304, as the AMC v-8s are externally balanced. Using the 360 flywheel on a 304 could cause vibrations.

Bob
tufcj

Thanks for the info?
I might go ahead and do as you indicated, put the 304 back together and see if I can get it to run until I can come up with the $ to get the 360 rebuilt.
Anybody out there have an idea what it would cost to rebuild a 360 stock. I called RoadMasters and they sell a rebuild long block for $1500 shipped with a 3yr 50k warranty.

!)ave

Does anybody know when swapping a 304 head onto a 360 motor if i can use the same intake manifold? and does the 304 use the same head gasket as the 360. I have to buy the whole 304 to get the heads so i am trying to decide which is the best way to go. Put the 304 heads on the 360 or put the 304 back together by itself. Currently the 360 is put together except for the heads and intake manifold. The 304 has heads, intake, water pump, timing covor and flywheel all off.

I know that the 304 heads have smaller valves in it. Not sure if it will work or not... Anyone?

Manifolds exchange, no problem there. I know Fel-Pro makes 2 gasket kits, 1 for the 290-304, and another for the 343-401. I'm assuming because of the bore difference, the head gaskets are different, because everything else is the same.

That said, If you're using a 360 block, I'd get a gasket kit for the 360. The 304 heads will bolt on, but the pockets in the 360s pistons aren't cut for the smaller 304 valves, so check closely for valve/piston clearance. You'll also lose a fair amount of performance because of the smaller valves.

Even though parts swap over, I'd build either engine completely, not mix/match parts.

Bob
tufcj

Thanks for the advice!
per your recomendation i have decided to but the 304 back together
and try to get it up and running soon.
possibley do a rebuild on the 360 at a later date
thanks again!
!)ave