318 Compression ratio

rick360 said

I was looking into Magnum heads too actually and yeah they are different than the earlier LAs. After all those years of shaft mounted rockers they finally changed them to pedestal mounts. I could find those in the junkyard rather easily. Now if I can get more power with those RHS heads then that wouldn't be bad either though. 400hp wouldn't be to hard to achieve probably. Thanks for the info.

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Yes, the magnum's should be readily available at your local pick a part. You'll want to have them checked for cracks, as its pretty common for them to crack near where the valve seats have been hardened. Not a big deal.

The RHS heads will definitely allow you to make more power. 400 hp out of a 318 though is probably pushing it a little for a street engine. I'm not saying it can't be done, I know it can. But your street manners will suffer a little. 300-350 hp is pretty easy to get, making that extra 50 hp to get to 400 takes some more planning. And keep in mind that the RHS heads (or any high flowing head) make power up high in the RPM band, and you'll need a bigger cam to take advantage of that flow. You probably won't spend a lot of time at 6k unless you're on the track all the time, but if its a street engine you will spend a lot of time at idle, so you may actually want it to be able to idle smoothly.