A Mopar 318 for my Barracuda
After a lot of thought, I decided to put a Mopar 318 in my Barracuda. I used a 1986 core because it has the "high swirl" 302 heads I wanted to run. They are supposedly worth about 10 HP over the earlier 318 heads and also less prone to detonation problems, which lets you run a higher compression ratio. Another advantage of the '86 and later 318 blocks is that they have provisions for a roller cam. Disadvantages of the later blocks are thinner cylinder walls (a .030" overbore is about the max - mine cleaned up at .020") and a propensity for the block to crack between the center head bolt hole and ajoing water jacket hole. My block was cracked, and even though the fix is easy, it adds an extra $100 or so to the build. I used a recipe similar to one that was published in Car Craft magazine:
- Block As noted above, I used an '86 318 block. If I'd had more time (or money) I would have found an earlier block. Since I'm not running a roller cam I don't need the provisions for one and I'd rather have a one that didn't require a crack repair.
- Crank For my application, the stock 318 crankshaft is plenty strong so that's what I went with. The Mopar 318 cast crank is actually a pretty good piece that can live at horsepower levels much higher than I'm running. My crank cleaned up with a .010" grind.
- Rods I'm running Scat I-Beam rods. They didn't cost much more than rebuilding the stock rods would have, and they have floating pins.
- Pistons I used KB-167 hypereutectic pistons. They are lighter and much stronger than the stock replacement style pistons available from Federal Mogul, and much less expensive than forged pistons. In my engine they come out to 10.1 to 1 compression ratio.
- Cam I'm running a Comp Cams XE268-H cam. This is a hydraulic flat tappet cam and I think performance will be excellent. The only thing is I'm going to be stuck with running oil additives or expensive racing oil. Thanks to control freaks in "our" government, most oil mfg's don't put ZDDP in their oil any more, so non-roller cams don't last very long.
- Heads As noted above, I'm running 302 "high swirl" heads. I replaced the stock 1.78"/1.50" valves with 1.88" intake and 1.60" exhaust valves and had the machine shop do a bowl blend.
- Intake I was going to run an Edebrock Performer (the Performer RPM doesn't match the 318 intake ports. After talking to Shady Dell Shop, I decided on a Weind ACtion Plus. The ports match the 318 heads and are a lot higher and smoother than the Performer intake.
- Carburetor
Updated November 5, 2009
