I own a 73 dodge dart sport. got it as a roller, and of course the 340 was pulled already, they gave me a 318. Just got my own 340 block. Can I use the 318 heads and just port match them myself, and then change out the valves?? I am a newbie, this will be my first build,any help is much appreciated.


thanks

 

k -

Will they fit and work? Sure, but you're going to have to do a lot of work to get the efficiency (performance) of 340 heads, due to the larger valve size.

Might cheaper just to look around for a pair of decent used 340 heads, worked or not.

Welcome aboard!

Archer

 

thanks so much for the welcome, work I dont mind, but is it possible, if I gasket trace the top and bottom ports, would I still have flow issues with the inside of the runners, are they smaller also???

 

You need to google up the casting numbers for the heads you have. It just might be that you have a good set of heads with a change of valves

 

thanks roadrunner I will check tomorrow,what are the different possiblities with the 318 heads??? thanks

 

I stated that a little wrong. You need to determine the casting no's for YOUR heads and then google them. Try putting in something like Mopar, xxxxxxxxxx where xxxxxxxx is the casting no, or google mopar, casting numbers

http://www.mymopar.com/headcastnumb.htm

http://www.mopar1.us/casting.html

http://www.mopar1.us/headcastnumber.html

 

Looks like I have 302 heads......I plan on port matching, but would going with bigger valves similar to 340 heads work that well, the internal passages are still going to be smaller on my 318 heads, right?? My buddy said it was like putting a big door on a small hallway.........whatya think? I am stuck on slapping these on my 340 block, so I need to make these work someway.

thanks

 

k -

As I said, they will "work" and if you're looking for a driver or cruiser, you're fine. If you plan on racing it or just want the most HP out of it, then you're going to have to open the ports and get new (bigger) valves to bring it up to 340 specs.

The other question that has to be asked ins what was done to the block? Things like compression, cam specs, intake/exhaust and trany/rear end specs all factor in.

Archer