Thread: 67 Sj 327

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I have a 67 small journal 327 block. I was wondering about a rebuild kit from summit. They have a kit that comes with everything to rebuild this block with a set of Speed Pro Forged Aluminum Dome pistons for about $500. I was wondering if this is a good deal or not. I want to rebuild this motor and run it in my 84 Caballero. With a nice torque street cam and a set of aftermarket heads, probably Vortecs.

I also have a forged steel crank from a 57 283 and I guess I could build a winding 302 but I don't know how much work that would be. I also want to eventually go to 4 or 5 speed with this car.

not much work at all. just get some nice dome pistons small chambered heads for big compression and add a 4 speed PRESTO instant fun the crank will drop right in <as long as its a small journal block!....scooter

I would stick with the 327 because with the weight of your Caballero, the extra torque would be a plus. 302's are a great little engine in a light car like a Camaro, but you have to rev the snot out of them to make power and they do not have much low end grunt. Make sure the dome pistons don't give you too much compression so you will have trouble with detonation on pump gas.

What's the highest c/r you think I can run on pump gas?

You have to figure out your DCR (dynamic compression ratio). You have to know your cam specs to figure it--go to the Keith Black website and use their calculator. As a guideline, 8.0 is maximum for iron heads, 8.5 is maximum for aluminum heads. It is not possible to tell from static compression ratio whether your compression is too high because cams bleed off specific amounts of compression based on the opening and closing of the valves. Essentially, the bigger the cam, the more static compression you can run.

As a guideline, 8.0 is maximum for iron heads, 8.5 is maximum for aluminum heads.

Man, then I better change the engine in my '93 Vette. It has aluminum heads and 10:1 compression. So does the Fast Burn 385 in my '34.

Originally Posted by Henry Rifle

Man, then I better change the engine in my '93 Vette. It has aluminum heads and 10:1 compression. So does the Fast Burn 385 in my '34.

Wrong--you are referring to your static compression. I run 10.6:1 static compression in my 383, and because of the cam (CompCams 280 Magnum), I get by fine on 93 octane. But I could not run a CompCams XE-274 because it would have put my DCR over the 8.5 limit. There is a very good explanation of dynamic compression ratio here: http://www.chevytalk.org/threads/sho.../0#Post1137028

Oops . . . my bad

So is the set with the Speed Pro pistons a good choice or what? I don't want to go through all the trouble and $$$ of machine work and then find out that I bought a junk set of pistons.

Speed pros are a good choice for street work.

The cpmpression ratio that counts is the dynamic compression ratio.

With the forged pistons, do I have to do any machining to them? I've heard they are stronger but have worse castings then cast pistons.

If you are going to use Vortec heads, then you don't want a dome piston because it will put you over 11:1 static compression, like the old '65 Corvettes. I would go with forged flat tops, and then choose as cam that will give you a DCR of between 7.75 and 8.0. That way, you will be able to run pump gas with no problems. When I had a 327 in my first street rod, I built it with Speed Pro pistons. I never noticed any quality issues--I think Speed Pros are the same as TRW. The only negative thing about them is they are heavier than the newer SRP, Wiseco, and other forged pistons. But on the positive side, it won't make much difference, if any, in a street performer, and the price is certainly better than other forged units.

you can run domes with pump gas and a bottle of octane booster i do that all the time the car does not ping rattle shake or explode! it runs fine. with the booster i am guessing about 100 octane thats why it will run fine!.........

So what would you put into this block? I'm going to be putting it together in my shed as money permits. I think that my Caballero has a 2500 stall and 3:73 open rear. Turbo 350 with a shift kit.