J heads

[doopdoop67]

I'm a little lost... I have a 72 318 and was wondering if I can put j heads on it. 318 is from a 72 dart swinger. Someone was telling me you can if its not the j heads with big valves?? I don't know if that's even a thing, if it is could you give me a way to check. Thank you !

 

[yellow rose]

Measure the intake valve.
1.88 yes.
2.02 no.

 

[rumblefish360]

Tell your friend to stop advising you and KNOW that a 2.02 J head fits a 318.

Signed, from the been there done that camp.

 

[Locomotion]

While 1.88" or 2.02" valves and bigger ports "could" be a performance gain, you really need other performance enhancements and more rpm to get the most out of them. IMO it wouldn't be the best way to go on a stock 318. For starters you will lose some compression because 340 & 360 heads have bigger chambers. 2.02" valve heads would fit, but they flow better at higher rpms. (Bigger isn't always better.) So you'd be losing some bottom torque.

One suggestion would be 302 heads with 1.88/1.60 valves and a little touch-up work in the bowls and ports. They also have smaller closed chambers, so you'd gain a bit of compression. Finding a Mopar friendly machine shop who knows what they're doing will help overall.

I'm sure there will be more suggestions.

 

[AJ/FormS]

You can but why?
You would have to re-engineer the whole engine.
Put 4.10s out back and call it done. Well maybe duals and a 4bbl; then done.5000rpm will get you about40 mph in first and,65 in second, and 95 in Drive. Winner!!!................

You might need to control the valves some. I put 360 springs on and tightened up the seat pressure. My 73 went 5200 plus like that.Scary-fast.

 

[rumblefish360]

A lot of people scoff at the idea of ported 318 head with standard 360 valves but the reality of it all is it is a great performer.

People seem to ride the aluminum head train and forget the old MP head offering of just what I said / deceived above that produced 55 more hp over a 360 head.

 

[273]

First thing is you got to decide what you want out of your 318.

A good all arounder street engine is idle to 5500 with a peak of 1:1 (hp:cid) at around 5200 rpm.

Problem with 318 is stock CR and heads will give you 300 hp at most.

A xe262h comp cam which is probably big as you want to go especially with stock CR. 4bbl and headers is said to make 282hp @5000 rpm.

So if your goal is over 300 hp something needs to be done about the heads if porting is an option then open or closed chamber 318 heads with some milling and porting and 360 valves can work really well.

If porting is off the table 360 heads can work if your rebuilding cause you can use pistons to give good cr. Or you could mill the crap out of the 360 heads my least favorite option.

Or better yet go with one of the magnum head option. A boost in CR and head flow.

I'd go with 4bbl, cam, exhaust and some gear.

And look for a 360 for level 2