What is the best way to build a 396 Chevy big block?

Answer 1

I do not know if I can think of a more broad question. You need expert advise, which I cannot give you here, as I do not have enough info, to answer you directly. I will try not to make this a novel. By your question I assume that by "build" you mean for performance. When hired to build a motor, I first ask 2 questions. How fast do you want to go, and how much do you want to spend?

My first consideration is always strength. That motor was available with a 4 bolt main block, which is what I would advise using. The 396 also had two different connecting rod sizes, thus two crank sizes. A 3/8's, and a 7/16ths. I would go with the 7/16ths. And they made a cast iron, and a forged steel crank. Forged is the way to go. This is basically the L-78 big block. Now, if you do not have all of these parts, do not worry. A 2 bolt main, small rod, cast crank motor will still run, but, just not have the needed strength to hold together making 600 hp. Gm would say that motor should not rev over 5000 rpm's. A 396 has a shorter stroke, and a larer bore, which is the perfect revving factor, so 5000 rpm's, wont make more than about 400 hp.

From personal experience I can tell you a 396 sings in tune right around 6900, to 7200 rpm's. It seems to make power best between about 5200, and 7000 rpm's. If you do not have the stronger parts I have mentioned, then you are just looking at a basic performance upgrade, so do a basic rebuild, and add a small cam, intake, carb, and headers.

I would go with around 9, or 9.5:1, effective mechanical compression ratio. A good set, of less expensive heads would help, but, do not spend a bunch on them. Edelbrock makes a good street aluminum head, that is reasonably priced. Whatever head you use, remember to use hardened valve seats, for unleaded gas.

There are other areas on the car that will enhance performance, without even touching the motor. Rear gear ratio, shift kit for the auto trans, and stall converters really are the best bang for the buck, but require lower gears in the rear, and posi, and, usually a traction device, and a tire.

If you build a mild enough motor, you can always enhance it with nitrous. A 100 shot, on a fairly stock motor will make a lot of difference, and keep the car milder, thus better mileage, and streetability. And done properly, will not cause a lot of stress on the motor.

As of late, I have been pretty impressed with the turbo charger guys. Something to consider. Way better than a supercharger.

If you have more specific questions feel free to email me. I do not charge for advice, ever.