Hey guys, sorry for the off topic question. My dads birthday is coming up so im looking at getting him some parts for his 74 Duster 318. The engine is bascially all stock except for a rebuild 10,000 miles ago. Stock heads, Edelbrock performer intake, 550 cfm holley carb, headers. Thats pretty much it. Im thinking about getting a cam and roller rockers for it. Im just curious if anyone knows anything about chryselr cams? I have a AFM n-21 in my stang, and it has a real nice lumpy idle, id like to get a cam close to the sound of mine, but im not sure how much lift/duration the stock headed 318 can handle before it smacks a valve? Can anyone help me out here? Thanks guys!
O/T Anyone kno anything about a Chrysler 318 motor?
- Thread starter Lynx331
- Start date
Lynx331 said:
-Stock '74 318 heads; ouch
-Fresh rebuild,Edel Performer, headers, holley carb; good
The Mopar 318 can be made to run. But it has things against it.
The stock cam, the stock heads, comp ratio, stock intake, and the stock manifods. It's the first three which you need to hit/change. Dont OVER cam it and keep port velocity up.
Cams;
For a 318 without knowing the gear ratio (assuming stock)
MP4452757 211/218@ .050 .410/.425
or
Summit 6900 204/214 @.050 .420/.442. This is the cam I have in my '84 truck and it is great. A good combo with the #302 casting heads. I got this cam at summit for 56.00.
My truck combo for comparison is; 600 cfm edel, #302 318 heads, Summit 6900 cam, headers, and performer intake (small port)
Either one of those cams can use the 340 stock replacement springs MP4120249. You will be safe on your PV up to .500 lift. But match the springs and cam.
FORGET ABOUT THE ROLLER ROCKERS. They are not as cheap as ford or chevy. Get him some rear gears instead. That duster should have an 8 1/4 rear end, 3.55's would do nicely
If you are not changing heads go with the SUM6900 cam w/ matching springs and 3.55 gears.
FYI
Typically the slugs on a stock 318 from that era (1973-1977) are down in the bore at least .25 of an inch. Some, like the 318 in my Aspen are close to .50 of an inch. So unless you want to change the bottom end your stuck with it. To over come the stock compression (w/o changing the short block) you need a set of heads that will get the comp up. My choices in order would be;
1. Magnum heads; 60-62 cc closed chambers, 1.92 I/1.60 E valves, 1.6 rocker ratio, flow @.500 is 209/150. Best improvement, but other parts required.
2. #302 casting 318 heads; 57- 60cc closed chamber, 1.78 I/ 1.50 E valves, 1.5 rocker ratio, flow at .500 = to E7TE.
3. LA 360 heads; 68-72cc open chamber. They must be milled to be useful on a street driven 318 or your comp will drop to 7.5-1 or so (it will run on pond water though
), 1.88 I/1.60 E valves, 1.5 rocker ratio, flows around 190 ish/140 ish @.500 depending on the casting.Hope this helps, anymore info let me know.
