Help! 383 or 400?

[GMC_Aaron]

I am considering the possibility of bulding a 383 stroker for my 1972 GMC, but I am also throwing around the idea of a 400 based on some of the threads in this site. I have read that it would be cheaper to build a 400. The Chevy small blocks are so versitile, it makes things confusing. There are so many choices out there, but I know I want to go with a 383 or a 400. With the 400 I get more cubes. I'm thinking with the 383, why build a smaller engine at a higher cost? Another question is, what about parts for the 400? Since the small block Chevy is so versitile, are all the parts the same up and down the line? Are there any parts in regards to the 400 that are hard to get? Would the heads from my 350 bolt right on to the 400? I'm just weighing possibilities and scenarios, but any feedback on advantages and disadvantages would be greatly appreciated. I've also read that 400 2-bolts are better than 4-bolts. Why is that? Thanks guys for the input.

[special70gmc]

no parts are hard to find but in reguards to the 350 heads bolting down the answer is yes, but steem hole have to be drilled for ex. the pic has steem holes drilled look between where the cylinders would be............................. -kyle

[kwmech]

Hey those cyl heads look familiar------and they are still for sale for 550.00

[dropped_71chevy]

There is an awesome build of a sb 406 in chevy high performance from a while back. they used vortec heads from scoggin dickey and it did very good. The new issue has another 406 build up with some higher peformance vortec heads.

http://www.chevyhiperformance.com/te.../148_0306_406/

the buildup for that 406 is expensive but doesn't have to be.
look over the cost sheet and you can see how they went overboard in some places

http://www.chevyhiperformance.com/te...6/index3.html#

Yes steams holes have to be drilled or you will encounter over heating issues.

You can also buy a stroker kit for the 400 that can push it all the way to 433 ci with a stock block. Its kit #7 btw

http://www.gofaststuff.com/kits.html

[Clancy68]

I am currently building a 406 myself,
the 400 is actually a little to a lot more expensive to build, especially if you are starting from scratch... however, if you have a good 400 block(they are a different casting, the bores are simesed)then its a wash as far as cost to build...
but theres a catch, a good core is damn hard to find nowadays for a few reasons, mainly most of the cores out there are bad no good due to cracking.
The reason i went with a 400 was I happen to come across a block on Ebay that was ready to build thanks to a young guy that lost interest for $450! if you decide to go the 400 route, try and find a so called 509 casting they can be identified by 2 freeze plugs on either side versus 3.
the 2 bolts are stonger becuase they have more meat in the mainweb areas. which is a big difference on a rather thin cast block like the 400.
with the 400 you want to go with 5.7 inch rods, the factory 5.565's have a bad reputation for wearing motors out fast, being noisey,and costing power.(too much side thrust in the bores) GM made them for the 400 to solve the cam, rod intereference issue. you will deal with the same thing on the 383, so thats a wash as far as one over the other, just go with a small base circle cam, or grind the corners of the rods when it goes together.

but theres hope, here the motor that i am basing mine on
http://www.chevyhiperformance.com/te.../148_0306_406/
in a follow up article they said a dual pattern cam would put it up into the 450hp ball park. with out any losses in the power or torque curve....so i was sold
also heres an outfit(mentioned in the article) who sells 406 short blocks for like $2300 which is a screaming deal!!!
www.coasthigh.com

thats all I can think of at the moment, I just had to learn all this stuff, so its still pretty fresh in my mind

--Scott

[Clancy68]

hehehehe beat me to the article haystack71
i saw your post when i finished mine

[Longhorn Man]

why build a smaller engine at a higher cost

This is my thinking too.
If you have, or locate a good block to start off with, then there is no reason to spend more $$ on a smaller engine IMO.

[GMC_Aaron]

What's the hp rating for a stock 400? I'm not gonna stack mine up too much. My truck is my daily driver and I tow trailers and such, so I'm not gonna go too overboard. I just want some more torque and hp. That's what I say now, but I will probably dump alot into it once I start building.

[GMC_Aaron]

Will the 400 scenario be a good combo with my TH400? Or should I do something with the tranny? I am definitely open to tranny suggestions because I would like to get something with an overdrive because I drive on the highway alot. The 700r4 comes to mind, but I've heard some conflicting reports.

[lukecp]

Stock HP rating on a 400 wasn't very good. Around 160-210 net HP. Not too bad though considering they only really existed during the smog years. Get rid of the crappy heads, cam, exhaust, and induction system and it will run like a raped ape.

A TH400 is a virtuially bulletproof tranny, and would hold up to a built 400 pretty easily. The 700R4 has the benifit of a 4th overdrive gear, but it will considerabaly more to build it to take the same amount of power as a TH400 does stock.

[busterwivell]

Well, I'll give you a different opinion. We just had this discussion at our club breakfast Sunday AM. 383 will be a torque motor. Several of the guys have 30 over 400's, and they have a tendancy to run hot when they are built up and you run AC (at least here in the desert). That's why 400's can crack (usually in the siamese area) Just a thought.
As far as transmissions, I've had a 700R4 in my Longhorn C30 with a 402 for a year now. I tow a 6500 lb trailer with it weekly and have had no problems with it. I know some people hate 700's, and I don't want to start a fight over it, but they have to be set up right or they will burn up quickly. My Studebaker had a 700 in it, too and worked flawlessly. My 47 will get one. We just swapped a 350/700R4 into my friend's 58 sedan delivery, and the first place it goes is the transmission shop to be checked over. Just my opinion.

[bigjimzlll]

Dont want to open a can of worms...but if your looking for stock performing hi torque...why not a big block? a crate 454 or 502 will do everything you need/want and wont be much more expemsive in the long run...

[68 Suburban]

I have also have been debating over a 406 or a 383. I guess I am leaning toward the 383 based on these reasons. I can build it with a newer roller one piece rear main block(I hate oil leaks! It drives me up the wall). I think this engine with the roller cam set up will help greatly with mileage, but I will still have that torque I want when I am towing up the mountains. I drive my burb 40K plus a year, so mileage is important to me. I can get the 383 1 piece rear main crank that has the mains cut (no need for spacers) for the 350 block for about the price it would cost to cut the 400 crank I have.

As for the 400 over heating? According to John Lingenfelter, that is a very wide spread misconception about the 400 engine. Some very early 400 engine had the overheating problem, but that was solved with the steam holes. Some people still may have problems because they use the wrong head gaskets that cover these steam holes. Everyone I know that is running a 400 base engine, has no problems with overheating.

As for 2 bolt versus 4 bolt, the 2 bolt is suppose to be stronger, but if you are not dragging it or beating the crap out of it, it will never matter. The engine I am building, I doubt will ever see over 4000 rpm, so I am not worried about it if I go with the 400.

The following is from: Page 13, "John Lingenfelter on Modifying Small-Block Chevy Engines"

[Moloko]

The 383 has the best bore/stroke ratio of any SBC, and because of that has the best formula for making power. I say 383 for sure. That is what is going in my Chevelle.

[bigjimzlll]

Originally posted by Moloko
The 383 has the best bore/stroke ratio of any SBC, and because of that has the best formula for making power. I say 383 for sure. That is what is going in my Chevelle.

How do you figure that? Nascar engines run a bore/stroke of 1.24
a 406 has 1.108 a 383 has 1.07..a 355 has 1.158..a 327(which I heard was the best production with a 4" bore) has 1.24... the nascar has a 4.155 bore with a 3.35 stroke crank..the larger bore helps it breath...just wondering how you figure the 383 has the best?

[Moloko]

Dont know, thats just what Hot Rod Magazine TV said and I've heard it from a few other people, including a guy I know who is on a team that campaigns in the Speedvision Touring Car series.

[68 Suburban]

Im not debating whether it is true or not. All I know is you can do a lot of things that Hot Rod Magazine (TV) does if you have bottomless pockets