Thread: 327sb vs 400sb

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Aight, well its come the time for me to go ahead and get another engine built..so i came here since the advice thus far has been helpful.. i want to know which engine is quicker stock...and i want to know which one is a better motor to build on... the only motors that ive been familar with so far are 355,and a 400... so when i heard about a 327 block i was just wondering what exactly i was getting myself into.. thanks in advance for the responses...

This is written with the assumption that both engines are first gen. small block Chevys.
Right off the bat you are giving up 73 cubic inches to build a 327 rather than a 400. Cubic inches equals torque equals smiles.
The cost will be roughly the same to build either engine.

Due to the fact that 400sbc's are externally balanced in stock form, I believe I'd stick with a 350.

In a mild to medium build motor, I am a believer that there is no substitute for cubic inches. Especially in a street motor. Just as Steve said why give up 50 to 70+ cubic inches. The 400 also has lots of torque which means you can run a higher gear and still have plenty of seat of the pants power at lower RPM, which is where you need it on the street. Regarding the external balance, that is not really a big problem, 454s are externally balanced too. You just need the right flywheel and balancer.

Good luck what ever you chose

Pat

Stu, that was my point. I have a stripped 400 in my garage that I ran in a '62 pickup and I learned the hard way that you need a 454 flywheel if you run a 4 speed behind it. Same goes for an automatic, you can't mix flywheels or flexplates on a 400 sbc with out doing some serious damage. In my case it was just replacing the rear main seal.

Go with the 400. That longer stroke is going to move you a lot better on the street. As far as the flexplate/flywheel goes, several manufactures have bolt on balance kits that bolt between the crank and the flexplate/flywheel so you can use your 350 (or smaller SBC) flexplate/flywheel on the 400 if you don't have one made for the 400. Speedway carries one and I've seen them advertised in several rod magazines also. JMO.

I agree theres really no replacement for displacement but thats not always the way to go, I've built some of my own 350's that did run hard against some of my 454's that I've built, but one thing is for sure chevy has given us a wide variety of motors to build. I wish the best for you.

Oh I forgot to tell you for my opion if I had the 2 motors setting in my shop and to make the choice of which one I would build it be no question to me.The 327 if it is a large journal if I was to get serious with it.The 327 in my opion will hold the RPM's better less likely to have as much problems out of the heads do to the steam hole in 400's which has a history of causing grief and in my opion I believe the 327 can be built to run just as strong as the 400. And thats just my opion for what its worth. best of luke again.

Having run a few of both engines I gotta say 400. "No replacement for displacement" is the best way to put it. The 327 is such a short stroke you have to spin the crap out of it to make it go. Like 7500 to equal the 400's 6200. The 327 requires a LOT of gear to make it work right. BUT, there ain't nothing like the sound of a 327 when it gets over 8000 rpm's, WHOOOOEEEE! And they handle that rpm easy. Had a roundy-round 327 on a 1/3 mile clay oval used to turn 9000, 6 something gear. WILD sounding ride!

Good luck either way.

For the street I'd go with the 400, can't beat that torque, I would use the 5.7 inch rods though, or even better a 6 inch rod.

Overall, if your doin' a build I would have to agree with the crowd. Cubes any day. However, if your talkin' about puttin together a stock motor I would have to ask what year the 400 was. By 74 or so the compression in the 400 was to light to be as strong as even a worn 327. So if your going to compare stock to stock say 67 327 to a 77 400, I'd go 327 all day. They had better compression and more aggresive cams, depending on what it came out of. Now if you're buildin' it before you put 'er back together you can spend the money and do the 400 right then by all means I would go with cubes. In stock form a late model 400 was not that great of a motor, not as good as the earlier models. Also all pre '73 400 had 4 bolt mains. These are the good ones, better compression, better cams etc... But some of the 327's were incredible motors too. High revin' screamers. Now you can build either to a factory spec that will make them both potent motors. I just like the way 327 rolls off the tongue, it just sounds good. Are you puttin' it in that malibu? It should have a 400, to new for the 327.

I have a 400sb in my 78 malibu now. 30 over 270h cam, sr torquer heads,rpm intake. I like it ok. My previous 79 malibu had a 350. I am considering going back to a higher reving 350. My last malibu was alot of fun. These little malibus make such good hot rods. This is my third and I have had Novas, Chevelles and Impalas.

Originally posted by urotu
Also all pre '73 400 had 4 bolt mains. These are the good ones, better compression, better cams etc...

But the 4 bolt blocks were much more prone to cracking a web... the 2 bolt caps are plenty strong for anything on the street.

I've got an offset ground small journal rod 400 crank, i believe 3.875 (suppose to be a 421ci when i'm done). ANYWAY do you guys know if this will need a special balancer and flywheel. The crank has also been knife edged and drilled in certain spots......basically a lot less metal than a stock 400 crank. I'm just wondering if a stock balancer and flexplate will work, or do i need something different.
Thanks for your time.

I agree with WJR. I have a 327 sitting around waiting to be built when I have time. There is no substitute for RPMs. Dont get me wrong, torque is pretty sweet, but RPMs can be just as much and consume alot less fuel. Look at indy cars for example, granted they are lighter, but you can have the same cubes in a 350 with 8 cylinders, or 350 with 12 cylinders and I bet the 12 cylinder will walk all over 8 when it comes to racing. As far as the 2 bolt or 4 bolt, i have always had a 2 bolt and have absolutely no problems.