AMC 304 to 360 rebuild?

[baddiesel]

Maybe a dumb question, but after many hours of research, I have to ask: Since the AMC 304 engine block is basically the same engine as the AMC 360. If I located a crank, harmonic balancer, flywheel, (lower-end rebuild kit) for a AMC 360, rebored the cylinders, could I essentially build a 360? I would prefer to purchase a 360 long block, but I've read too many bad reviews. My block and heads are good, just wore-out. I wanted a little more torque. Thought I could build a 360 from my engine, if I could locate a good AMC 360 crank, flywheel, and harmonic balancer. And no, haven't had much luck in locating either of those items, without purchasing an entire junkyard vehicle-engine, and then, it's an automatic. So, I can't find a flywheel for a 360. Sorry for the long thread, but thanks for your comments & info.

 

[Niedhogg]

Maybe a dumb question, but after many hours of research, I have to ask: Since the AMC 304 engine block is basically the same engine as the AMC 360. If I located a crank, harmonic balancer, flywheel, (lower-end rebuild kit) for a AMC 360, rebored the cylinders, could I essentially build a 360? I would prefer to purchase a 360 long block, but I've read too many bad reviews. My block and heads are good, just wore-out. I wanted a little more torque. Thought I could build a 360 from my engine, if I could locate a good AMC 360 crank, flywheel, and harmonic balancer. And no, haven't had much luck in locating either of those items, without purchasing an entire junkyard vehicle-engine, and then, it's an automatic. So, I can't find a flywheel for a 360. Sorry for the long thread, but thanks for your comments & info.

I don't know a lot about this subject, but what I understand is that the heads on a AMC 304 are very poor and expensive to rebuild, or at least to modify and add larger valves, they breath poorly. I did a little research on that subject when I was building my CJ, and trying to decide wether or not to build up my AMC 304 , and I decided against it.

Good luck.

 

[baddiesel]

Thanks for the response. I'm thinking it might be just plain cheaper to rebuild what I have, and maybe invest money in a TBI fuel injection system to improve performance and fuel economy. It's very difficult to locate the AMC 360 flywheel, otherwise, I would purchase a Jasper long block and be done with it. Merry Christmas!!!

 

[mylittlecj5]

Not sure why you can't find a 360 flywheel, a quick google search nets THIS ONE within the first couple hits...seems pretty affordable as well.

 

[baddiesel]

Thank you very much, you've made my Christmas! Gotta wait until after the holidays to order my AMC 360 long block. I've been fighting a flu/cold virus, so the brain is a bit more slow than normal.

 

[Scooter402]

AMC 304 cylinder bore is 3.75", a 360 cylinder bore is 4.08". this means that you'd have to bore the cylinders over by .33", which is over 5/16". The only good thing is they share the same stroke at 3.44". The only thing you could do is have the cylinders all re-sleeved to fit, which would net you more money and work into the block than finding a 360 would be.

Good luck with your rebuild.

 

[Niedhogg]

AMC 304 cylinder bore is 3.75", a 360 cylinder bore is 4.08". this means that you'd have to bore the cylinders over by .33", which is over 5/16". The only good thing is they share the same stroke at 3.44". The only thing you could do is have the cylinders all re-sleeved to fit, which would net you more money and work into the block than finding a 360 would be.

Good luck with your rebuild.

Bingo! I knew there was another reason it really wasn't worth the effort!

 

[baddiesel]

Guess I received misinformation, thought AMC 304 , 360, and 401's all shared the same block, just different bores & strokes. Which in turn would require different crankshafts, rods and pistons, depending on bore size and stroke length. Plus.....different camshafts & harmonic balancer. I have decided to get a Jasper rebuilt AMC 360 long block, and re-use the remaining parts off my AMC 304 . *(except the flywheel & harmonic balancer). Thanks for your comments and info.

 

[CJ]

Just a little more info to help mess up some things.
AMC 304 heads are not poor, they are sized for the small CID engine and flow very well due to the dog leg ports. Dog leg exhaust port (on all gen 3 engines) flow better than most rectangular or oval ports.
BUT, putting the small valve heads on the larger CID engine is futile. AND. you cannot drop 360 or above heads on a AMC 304 because the valves will hit the cyl wall, and relieving the wall still leaves a shrouded condition negating the larger valves.
As for a few other differences, the biggest reason that the 401 is so sought after is the block has a high nickle content and of the AMC v8's, the crank and the rods are forged! Unfortunately a 401 has less cyl wall thickness so you need a better cooling system/
The 360 is a very close 2nd to the 401 and can be bought for much less money...

 

[baddiesel]

Thanks for the info. I hope the AMC 360 long block from Jasper includes the heads. I won't be able to find out until tomorrow. Not to change the subject, but I'm also trying to locate the engine oiling modifications. I did save them somewhere, this cold/virus is taking it's toll today. Hard to enjoy Christmas.

 

[CJ]

This thread covers it all... Unless your running your v8 hard the stock system works well, if you insist on modifying the oil galleries and such there are diagrams in the thread you can follow...

-->> http://www.jeep-cj.com/forums/f2/amc-v8-build-oiling-questions-14918/

 

[mtnwhlr]

Long block means with heads a short block means no heads.

 

[baddiesel]

Thanks for the oil mods!!!; I won't be racing, or running it hard. I like the added insurance of getting oil to the back parts of the engine. And, thanks for confirming the definition of a "long block". Now, I just have to have faith in a Jasper rebuilt AMC 360.

 

[1986cj7]

Thanks for the oil mods!!!; I won't be racing, or running it hard. I like the added insurance of getting oil to the back parts of the engine. And, thanks for confirming the definition of a "long block". Now, I just have to have faith in a Jasper rebuilt AMC 360.

With a 3 year/ 100,000 mile warranty I wouldn't be to worried.

 

[baddiesel]

Haven't called Napa auto parts yet. But, I've called O'Reily, Autozone, and Advance; prices are much higher than I anticipated for an AMC 360 long block. $1765.00-$1999.00 for the engine, and $300.00-$335.00 for the core charge. Got a price quote for a 401, and it was *almost as cheap as the 360. BUT, that $1200.00 core charge will raise an eyebrow. The "auto parts chains" around here do not contract with Jasper. They use SureFire, Power Torque, and Spartan. I've never heard of them, but they offer 3 year unlimited mileage. Just my $0.02.