:question: Ok, so at the advice of several wise POR Members I used the search function and answered a lot of my questions. I also found the Froadin (http://www.froadin.com/engines.html) site, but I still have a few questions so I'm hoping you wise mechanics can lend some knowledge...

I'm going to be building an AMC 360 to swap into my CJ5 that currently has an AMC 304 and a T-18a tranny. I have a set of rebuilt AMC 304 heads and I've been told by a mechanic that I can put them on the 360 to get more low end torque out of my engine. I visited the froadin site and they say you can fit 360 heads on a 304 with a little machine work, but can you do the vise versa and would this be advisable?

I'm building this jeep strictly for rockcrawling, but it will also be my daily driver. It will have around a 101 to 1 crawl ratio after I throw the tera low kit into the dana 20 case. So what do you guys think is this guy nuts or is it a good idea? :question:

Wouldn't putting 360 heads on your 304 increase flow while decreasing exhaust backpressure, resulting in HIGH-END gains?

better to go with an RV cam or one of those "torque" cams.

Jake

Originally posted by Jakesteramalamajama
Wouldn't putting 360 heads on your 304 increase flow while decreasing exhaust backpressure, resulting in HIGH-END gains?

better to go with an RV cam or one of those "torque" cams.

Jake

I think he wants to slap the 304 heads on the 360, which *probably* would give him more low-end. BUT with 100:1 crawl, IMO the 360 should be plenty torquey.

Yes, I want to put 304 heads on a 360. Main reason I am thinking of doing this is because I already have a set of rebuilt 304 heads, and it would cut down on the rebuild cost of the 360 if I could just slap on 304 heads. Thanks.

:emb:
Oh! Sorry. I misread your post. the answer is: YES. That setup will build more low end torque because of the added backpressure caused by the narrower ports.

Sorry--been one of those days...

Jake

You guys have it all wrong. It not a backpressure thing ,it's intake velocity thing, High speed intake charge thru a small intake port and valve improves low end power. It works very much the same way that a spread bore carb gives you more low end than a square bore.

it may give you a little more bottom end but with the smaller valves you'd be kinda choking the motor some since all 360 were designed with the larger valves. I've got both a 304 and a 360, both are stock and I'm plenty happy with the low end torque of the 360, I've got it in a jeep with 4.56 gears and 42's with a t-18 and d20 and it provides good power to move the 42's, I personally wouldn't put the smaller valve heads on the 360, but thats just my $.02

Justin

Would I be in effect hurting the engine by putting the 304 heads on the 360? Would it possibly reduce the life of the engine or maybe reduce top end power? Since it's going to be a daily driver with occasional use on the highway I wouldn't want to take away from the top end, but if I could improve the bottom end and since I already have the 304 heads built I'll just use them. What do you guys think? Am I taking a step backwards by doing this? Thanks for all your help. :smokin:

I think you forgot to mention that you also live at 7,000 ft above sea-level, and probably will be wheelin above 12,000 ft.

Damn, did I ever answer your post on my board? I have so little time anymore.

Actually the gain is more from the smaller valves. Two reasons, smaller valves have offer less resistance to the air/fuel mixture velocity. Second they are not as shrouded as the larger valves are.
The 304 runners are basically the same as the 360 with the exception of some extra material right before the valves. Kind of making an hourglass shape.
Running 360 heads, definitely a good valve job, and possibly better valves if $ permits. Then run something like a Torker manifold with a smaller 600cfm ish carb (or quadracrap) with a 1" spacer. This longer path for air flow adds torque, but you have to run a smaller carb or you will just puddle fuel.

The smaller 304 heads will have a slightly better power band then the larger 360 valved heads. But because it is a bottleneck causing it rather then a evenly contoured runner means it hurts any performance above that low point.