71 and 67 318 heads??

[soaringcowman]

Questions is there any difference between a set of 67 and 71 318 heads? i've got the 71's on my car now with a few bad valves and have a set of possibly good 67 heads. i was gonna swap them out if there isn't a difference??

thanks
adam

 

[66dartgt]

Probably next to zero difference other than the casting number. 1.78/1.50 valves, open chambers etc. Both lack hardened exh valve seats. Why not get a set of the 302 heads and plop them on - wont cost that much if you have to redo a set and they will have closed chambers (higher comp ratio) and hard exh seats. With a little intake port work you'll have better heads. my 02.

 

[soaringcowman]

hey thanks alot for the info, i've always loved mopars, but this is my first one so what exactly are the 302 heads off of? and is there any modifcation i gotta do to put these on instead?

 

[IndianaDodge]

check out this post here on FABO about the 302 heads

http://forabodiesonly.com/mopar/showthread.php?t=24252

 

[340mopar]

'67 heads will have a smaller combustion chamber so they will raise your compression some.


Chuck

 

[66dartgt]

The 302 heads are a direct bolt on, no changes. The intake ports are pretty narrow thru the pushrod bulge and that area should be shaved down as much as possible. If you get a set you'll see what I mean. You can find these heads on just about any late eighties thru early 90's 318's, diplomats, vans etc will have them. Make sure to look for heads that have 5 valve cover bolt holes and the last 3 digits of the casting are 302.

 

[soaringcowman]

'67 heads will have a smaller combustion chamber so they will raise your compression some.


Chuck

now will this inprove any performance, or will it decrease?

 

[66dartgt]

It should increase because you will have a higher comp ratio according to 340 mopar. I am not 100% familiar with the 67 heads, I know 66 273 heads are closed chamber, but not sure about 67's. Take a look at the underside of the 67 head, in other words the side facing the pistons. Is the combustion chamber a circle that is below the head surface or a sort of half moon shape that is flush on one side with the face of the head ?

 

[BJR Racing]

It's a open chamber but smaller in diameter.

 

[moper]

It's a open chamber but smaller in diameter.

Yup. I think they start around 60cc. I have a milled set that is 52cc.

 

[BJR Racing]

Yep and it doesn't take much to drop the cc's either.

 

[moper]

It was a while ago, but I think they were cut .050. I know I had to cut the intake to match them, but the chamber was slightly relieved too.