Since getting my 72 i have been exploring many ways in which to improve performance. I see that the 383 stroker is a popular mod. But i figure if i have to spend money getting my block machined I might as well do it for a 400ci block. The stroker requires new crank, rods and pistons and the cost would be the same for a 400. From my way of looking at it a better decision would be to make all the modifications to a 400ci engine so u get the extra cubes. I understand that the 400 may not be suitable for racing but for the powerfull street car isnt it the perfect small block?


[Modified by xrated, 2:22 AM 8/21/2001]

 

Having recently spent an arm and a leg building a stout small block 383 stroker I would have to agree with you analysis. Problem was two fold. First sourcing a 400 block that had good wall clearance and strength for boring. These blocks have been widely criticised for poor tolerances and over heating. These colling problems can be fixed by a knowledgable machine shop. A good book to read is the Small Block Chevy by Lingenfelter. He really spells it out in plain English, as does David Vizzard.

If I had it to do over again I would have probably just bought a crate motor from Bill Mitchell hardcore racing. He uses his own block that has fixed the problems of the 400. He is able to bore and stroke it out to 427 cubic inches and beyond. You get all the performance of a big block with the wieght of a small block. What could be better. Not to mention warranty and dyno tuned before shipping. Its more money to go the route of a crate 400 plus motor but not that much more. That is of course if you are comparing to building a stout 383. With Scat crank, forged rods, forged pistons, internal balancing, roller cam, aluminum heads yada yada yada.

Hope this helps and let us know what you decide.

 

Sorry to hear about the 400ci block shortage. U can buy new blocks at reasonable prices. I looked at a new one for $1000 Aus. 1K seems worth the money when the entire engine will cost me around 5k anyway. Thats a complete engine including new World Heads.

 

I put allot of thought into a couple of strokers 383 and 393 ci. I decided against any large journal stock 400 block as a base for anything. The only way to go is after market 4.125 bores with 350 main journals and only internally balanced.

You are correct in thinking that the cost to build a 400 is the same as a 350. Long rods and good heads make for very powerful 6000 ish rpm motors.

 

There are a lot of guys with 406s and stroker 400s making good power (and hella torque ;) ) with no problems. Just don't start with a crappy block, and get the work done at a reputable place. 400s have a bad reputation which is mostly undeserved. If I do another small block, it will be without a doubt 4.125+ bore based. An aftermarket block would be nice, but I haven't seen them for less than $1800 or so, I don't think that is worth it unless you are making 600+ hp. I'm sure a studded 2 bolt 400 would be more than comfortable spinning 6500 rpm and making over 500 hp. Splayed 4 bolt, better yet. Theres some guys on chevelles.com (a great forum, especially for hot rodders on a budget which is more rare on this forum ;) ) who spin balanced but otherwise stock 400s to 6500 with no problems and have done so for years.

Remember (and this should be a rule on this forum) that overdoing a buildup doesn't hurt, BUT it doesn't help (and it's a hell of a lot more expensive too). I should talk, I got 4340 H beams in my 6500 rpm 450 hp small block I say by all means spend a couple hundred bucks (or more if necessary) and some time and find a nice 400 block.

Rob

 

I'm running a Dart Iron Eagle (GM Rocket Block) with my SBC427. Certainly, the aftermarket blocks are more expensive than a production 400 block, but consider the big picture. The aftermarket blocks are fully CNC machined, needing only the bores honed to fit your pistons. They are fully align-honed, decked, and the lifter bores are indexed. For the price you can get splayed 4-bolt/stud steel caps, taller deck heights, 350 or 400 main journal sizes, and a choice of SBC, BBC, or 50mm roller cam bearings.

Unless you are lucky, most production 400 blocks are going to need to be overbored and honed, probably align-honed and decked, and if used in a high-performance applicaiton, you may wnat to add splayed caps. Adding splayed caps and ARP studs can easily cost you $500 for the caps, bolts/studs, and machining. Boring/honing with torque plates and gaskets can cost you over $200, align-honing another $150, and decking around $100. So you could easily spend another $1000 getting a used $200 SBC 400 block up to snuff, $1200 total. What you end up with is a used block that's already been overbored at least once and features thinned, weaker deck surfaces, and main bearing webs and bulkheads. For the additonal $300-400 it seems worth it to me. And if you ever need to refreshen the motor up, more than likely, you'll end up having to take a production SBC 400 block .060" over which is typically not recommended, and in alot of cases you end up with very thin, unstable cylidner walls. Some of the better, high-performance oriented machinists won't even overbore a production SBC 400 .060" becuase they know how thin the walls get.

I'm certainly not saying everyone needs a $1700 aftermarket block, but when you consider the big picture, they may be more economical in the long run and you end up with a much superior foundation for building a very powerful and reliable high-performance motor.

 

I picked up a 73, standard bore, 400 complete engine last spring for $300. Obviously all I want are the shortblock and the dress components. Someday I plan on building a stout 406 for a yet-to-be-determined corvette. I just read about a deal that made me rethink that situation though.

Chevy High Performance just built a 355 based on a late-model (1-piece main seal) Caprice motor that came with a stock low perf. roller cam. They rebuilt the shortblock with normal good 350 parts, replaced the cam with a GM HOT cam (with the original roller lifters and spider assy), installed a new timing kit, Vortec iron heads (reworked with LT-4 springs), and a Performer RPM manifold and a Holley 750. They estimate $2400 for the whole build up, and although they haven't run it on the dyno yet they expect ~420 HP and ~430 lb-ft. Seeing that this is essentially a ZZ430 with a slightly less stout bottom end and Vortec heads instead of Fast Burns this seems reasonable. Imagine the same motor with a 5.7" rod 383 rotating assembly! It's tough to argue with the economics of this pretty basic type of build up whether you go 355 or 383!


[Modified by 69L71, 1:07 PM 8/21/2001]

 

I would have to agree with Monty - aftermarket block is the best way.
But if you're going to spend the money, the aftermarket big block with a 4.5" bore is only a couple hundred more.
If you dropped in a forged 427 crank (3.76") in that 4.5" bore block, you would have a 467 cubic inch screamer with a short stroke. I think this is the combo they used in the Can-Am motors in the early 70's.
I feel that this is the perfect motor for a 'Vette.
Now I want one :yesnod: :yesnod: :yesnod: