I want to go with the 400sb for the tons of torque it produces! Also the 400's are getting scarce from what I read. I think it would be cool to talk about it at a car show. The 400 will be going in a 79 w/ auto and 355 gears. Power will be 450hp w/ 500lbs. No fancy parts needed for this build, maybe even Dart iron heads and a 962 flat tappet cam. Old school!

 

400 good choice, but it will take some fancy parts to reach 450hp & 500lbs torq believe me. Just to name a few, good heads / cam / intake / carb / headers etc.. etc.
Hope you get your wish.

 

With the new low cost dart block that's out now, just get a new block. There's so much to worry about with a 30 year old GM block that the extra cost is easily justified by the significantly better quality, vastly improved design, better iron, four bolt mains (the RIGHT way), modern CNC machining, little risk of core shift, roller provisions, the list goes on...

There's just no point in paying to fix up an old 400 block unless you already have it and know its history. I did it last fall, and if it wasn't for sentimental reasons I'd be very sorry I went with a GM block. My father and I built the 400 I used in my C3 last fall originally for my Camaro (my first car, he and I ressurected it as a father-son project 20 years ago and I'm doing a frame-off restomodification on it now). I spent almost enough on the block to pay for the aftermarket block, and when the block was ready for assembly I still had a block with thinner cylinder walls, weaker bottom end (main caps AND the webs they bolt in to, either pay extra for retro roller lifters or be stuck with flat tappets, inferior crankshaft journal oiling, and softer iron. It wasn't an outright mistake, but I didn't get as much for my money in technical terms.

If I was in your shoes, I'd think it over very carefully. It's already financially almost a wash to go with far superior (than recycled GM parts) Scat rotating assembly. If you don't already have parts that you have an emotional attachment to, seriously consider this!

 

Al Davis, is there a weight consideration when going to 400 block? I know that if I go to BB that added weight creates the need to beef up the front suspension. (or deal with the softer handling) Is the 400 block heavier? How much?
I have been thinking of the 406 or stroke to 427, AFR 195, roller lifter and about 550ish cam.

 

the 400 block is the exact same dimensions/weight as the 350 block just with a larger bore (4.125" vs 4.0")

I've been dreaming the same thing as you for a while.

 

Wouldn't it weigh less, since the water jacket is smaller by over 50 cubic inches?

 

Never regretted going with the 400 block here... If you have money, they make some pretty awesome aftermarket large displacement small blocks now - like Motown.

 

You can get a 454 small block from World Products. Your average non-Chevy guy will never know the difference. Dress it up like stock in a '79 and you've got a great sleeper.

 

Make sure you get a 4 bolt 400 block engine,because a friend of mine used a 2 bolt 400 and snapped off the balancer ,crank broke,do to being one key way that stabilizes balancer.4 bolt blocks have 2 key ways on the crank. We have learned from other engine builders that this is a common problem with the 2 bolts.You can have a machine shop machine the crank to fix problem.It will cost you more money for parts for a 400 too,you will find that out.The hp you want you can get out of a 350 .

 

^ 4-bolt blocks are actually weaker, the outer bolt holes go thru the main webbing in a critical area. If your friend broke the snout off the crank, it had to be a crank problem, not a problem with the block. I've torn several of both down, never noticed a difference in cranks, but I'll look at the cranks I have in storage to see.

 

I'll agree you can build a 350 to the HP he's after, but the 350 will not have the tq. the 400 can produce.

Your correct to a point on 2 bolt vs 4 bolt. 2 bolt are recommended up to about 400hp. The 2 bolt is better up to around this 400hp zone, after that hp some recommend a 4 bolt. My 406 sb is a 2 bolt and it's pushing 490 hp never an issue with the 2 bolt so far, so I do agree with your post it's just a gamble.

 

Exactly ,its the crank,2 bolts only have 0ne keyway and the 4 bolt cranks have 2 keyway.the 2 bolt crank is not as good at stabilizing the balancer ,the one keyway will egg out and the crank will snap at the balancer.That will happen when you run higher hp .You might want to check out the 2 cranks closer.Alot of people miss this.I did,engine shops deal with this stuff alot more and know things like this that us regular people miss.

 

You will be alright as long as you keep your rpms low
You can run 600 hp with 2 bolt ,just have to keep rpms down.

 

5600 rpm is my best range, but there are times I take it up to 6500. I tear down the engine every winter, so far so good.

Didn't mean to highjack your post Al Davis. But plan on $10.00 for every HP your after for cost approx.

 

All opinions are welcome. I am wanting to build a 400 just for the big torque that it produces. It will be street driven, maybe 425hp high 400's for a torque range. I even have a GM 962 cam that I might use along with a set of Iron Eagles 200's. Nothing crazy, just for fun.

 

I was looking at a used 400 (509) at a machine shop. They had a bare block w/ 2 bolt caps for $500. Engine is not bored 30 over yet, the engine was as he said cleaned and "magged" for cracks. Is there anything else I should ask or look for?