Which one is better? Give reasons,cheaper to build, cheaper to modify, more potential for power, etc.

 

Price isn't much difference as long as you can find a 400 block, you can reuse your existing 350 block for a 383 (providing you have one of course). Remember one thing is that the 400 will not be a roller cam block, so if you want a roller you'll have retrofit it, no biggy, just a bit more expensive, and you need to be aware. Also remember to drill the steam holes in the head for the 400. But you won't have to clearance the block for the stroke with the 400 (except some aftermarket cranks have larger throws that need to be allowed for). The stroke is the same so you won't gain much torque, but you'll probably be able to pull a little more hp out of the 400. If your not building it yourself remember that a lot of shops will charge a premium for a 400, just because. And I'm doing my next 400 .04 over so I can call it a 409
If you've got a block in good shape use it, if you're going to have to buy a block anyway, go for the 400.
John

 

ud be surprised how much... 20ft/lbs easy.

There is also the issue of 400s not being drilled for mini starters will parallel bolt holes (can be fixed during the machineing process).


But, in the long run,, its worth it.

 

400.

 

dont blame the motor for not performing.

They need intake airflow period

 

I would not go to the trouble of building a bigger engine and then slap on all the original L98 parts.

 

Hmm, looks like the 383 would be less of a pain, but I would like those extra cubes. I have to drive my car everyday so I would have to get a doner block for either one. My freind has a 400 laying around, but its a Pontiac block from a 68 Tempest. Would it be as good as a chevy 400? I was also considering a new block from World. As for its breathing, I was thinking of going with the LT4 intake and for heads either Vortec or AFR. It will probably even be supercharged in the future. Keep in mind I want something that is very streetable, but still beat up on Mustangs and 4th gen camaros.

 

I have heard from a professional engine builder that it is alot more dificult to maintain a 406 or 400. He says those enginse don't hold together that well and that most old ones are rotted out. He told me to either get a new motown block and do it that way or do a 383....so I am doing a 383

 

when my 305 blows i'm going to put a 400 in my z

 

The motown block is very tempting. Thanks for all the info guys. Another option I forgot in the poll is a 427 stroker. What are your thoughts on that? Also, how much should I offer my friend for his 68 Pontiac 400? Its in pretty bad shape, but can be saved I think. Someone is trying to trade him a 350 for it. I am trying to talk him into keeping it or selling it to me. Anything but trading for a 350.

 

Seems to me a 400 is a SBC just like any other

If it falls apart as a 400, it just as easily would have fell apart if it was a 350 block. Just make sure you've got a bottom end BUILT for what you're doing. If you're going to spin it get some strong rods, get a forged crank, yadda yadda.....

If you can find a 400, its a SBC just extra cubes
(and you know what that means )

 

The pontiac block will be much more of a pain, and probably much more expensive. You will need a different trans or an adapter plate to even get it to bolt up. Also parts for the pontiac motors are not as cheap or common.

I would advise you to keep looking and find a chevy 400 block. They are great engines, and everything will bolt up/swap over from any other small block chevy. As stated earlier you will need to get some good flowing heads and some special machine work. But I can't see that the machine work would cost more than clearing a 350 block for the 400 crank. If done properly a chevy 400 can be as reliable and streetable as any other small block. And everything being equal, the 400 will make more power than the 383. Now, if you were already running a 350 that was in need of rebuilding...I would probably steer you in the direction of the 383.

Just remember to do it right the first time. Buy quality parts and you will get quality results. Dont skimp out on the heads, and make sure your cooling system is up to the task. Good Luck!!

-peace