Workin On 59

Awhile back there were some posts about building a 400 smallblock. I called about a low mile mildly built one and I want to go see it tonight. I could not find anything in the archives on the 400 but I remember one of the Forum regulars is running one.

The one I called about has been bored .040 over and the crank has been turned, mild cam, Edelbrock intake (Performer RPM I think) and is said to have 2.02 exhaust valves.

This motor would be for my 59 project, mated to a BW Super T-10, 3.36 rear.

Any comments and links to prior posts would be appreciated.

Is boring .040 over acceptable in the 400 block? What heads came on a 400?

Thanks, Doug

Nowhere Man

all I have been told about 400sbc is they over heat, and being bored .040 over is not going to help that. there are much better engines out there for your car.

claf

I had one in a stock '76 Monte Carlo. Well over 100K with no problems or overheating! Only a 2 bbl, didn't seem to rev like a typical SB. Bob

Hirevsjoe

I've had two different 400 smallblocks in different cars. As long as the heads that are on them have the extra steam holes drilled in them there is no problem with over heating. The stock heads are no good. They have really small valves and don't flow well. Use a good set of 350 heads or just spend the money and buy a good set of aftermarket ones. .040 is as far as you want to go without having the block checked. I have one that is .060, but it is a perfect block. the motor will move your car great. 400's are great torque motors. If you are looking to rev it you will want to change to a better rod and piston set up.

Workin On 59

Thanks for the replies guys.

The guy selling it built the motor so he should know if the heads have the proper steam holes. The kid he built it for only ran it about 500 miles in a 79 Malibu, then traded to the same builder for a hotter smallblock. My guess is the 500 miles on it were not easy ones.

I'll definitely get more info on those heads and make sure the right head gaskets were used as well. I think I can get it for $700, maybe a little less as he wants it out of his shop and is not doing Chevy motors anymore.

Doug

mikem350

No Chevy motors??? That's un-American

Hirevsjoe

If he's decided not to do chevy motors. Someone needs to tell him that he is really going out of business >

DZAUTO

I'm the one with the SB400 in a 56.
In the past 30+yrs, I've built about 25 SB400s, as well as too many other engines to count.
FIRST, over and above anything else, there is nothing wrong with a SB 400. Period.
Yes, they do require some special attention during machining/assembly, but nothing that is really exceptional. Ideally, you would like to keep the over bore of a SB400-------------------FOR A STREET-PERFORMANCE ENGINE----------------at .030 over. BUUUUUUUUUUT, .040 over is OK. Pistons that are .060 over are available, although, many people, including me, consider .060 over for a SB400 to be outside the acceptable limits-------------------FOR A STOCK BLOCK------------------ but OK for an aftermarket block such as a World block. These blocks (as you probably already know) have siamesed cylinders which means there is no water passage between the cylinders. Thus, between each pair of cylinders, there is a pair of steam holes which corrospond to holes in the heads for the purpose of allowing steam to escape from the block into the water jacket in the heads. For a serious race engine, these holes are not necessary but SHOULD be present in all street SB400 engines.
When a SB400 is machined, is is essential that a VERY COMPETANT and KNOWLEDGEABLE machine shop be selected. Before spending your good money on a 400, first have it thoroughly inspected and magnafluxed. From that point on, its just a matter of what you want to get out of the engine. Generally speaking, there is one factor that should be kept in mind when building a SB400, its best to build it to perform UNDER 6000rpm. No matter how how you slice it, 400 cubic inches is 400 cubic inches! That translates into plenty of torque, which is more than plenty to turn a high rear gear such as a 3.08.
In my family, there are 4 SB400s and zero problems with any of them. Also, I've never known of any problems with the 400s I've built for other people.
I prefaced this reply with the importance of spending some extra money with a good machine shop to assure that the 400 block you start with is a sound core. Once that has been determined, or, the block has been prepared and machined to make it a sound core, then you will have as good a foundation to build a healthy engine as you would with nearly any other engine.
All of the above also holds true with a set of heads.
If the engine that you plan to look at has been properly machined and assembled (either take his word for it, or tear it down and examine it), then I think you will be more than pleased with the results. A SB400 will fit anywhere and accept any accessories/hardware that is common to any other small block.
I DO NOT claim to be the ultimate guru with SB400s, but I certainly have considerably more hands on experience with them than a lot of people.
If you have any questions, I'll be happy to attempt to answer them.
Hope this helps.

Pop Chevy

I think the 400 small block is a great engine !! I have had about 4 of them in all kinds of things. One was a 77 Suburban with 180 thousand miles, still ran ok. Used it to pull my stock car around. I put one in my 57 Chevy pickup, w/ cam intake and lifters. It pulled like a bear !! 60 over is about as big as you can go. don't worry about the heating rumors, I never had any problems. But it's true about the heads, they would crack around the seat area. The local stock car track has a 406 rule on the sprint cars, the low buck guy's buy every block they can find. That's what they use ! I can't remember the high nickle casting no. though, maybe someone else here can.
Pops

vetrod62

If you want a low rpm torque motor, go for a 400 motor. If you want high HP, high revving motor, put a 350 crank in it with a decent set of heads and make a 377 ci. The car below is a $2500 377.

Workin On 59

OK guys thanks for the additional info and tips. It's late and I just got back from looking at the motor.

It's real clean. Heads are 487 casting (350 ci from '68-'79, 75 cc combustion chamber as used on 71-72 LT-1 according to what I looked up online). Block is casting 3951511, E2872, which I believe is May 28,1972 and is a 4 bolt main.

I wanted to hear it run, but the guy had a dead starter so we'll try again tomorrow with a new starter.

The seller could not remember if the heads had been modified for the steam tubes necessary on a 400 (obviously hugely important), but offered to pull a head to check. He built the motor over 2 years back. A local reputable machine shop (Westburg Engine ) did the head work.

I'll add more info as available.

Doug

I'm Batman

I have a .060 400 block in my basement. The bores are in nice shape, but I need to have it looked over by a machine shop before I start assembling it. If it has any bore problems I'll probably just have it sleeved.

There's a post floating around somewhere in the C3 section with the information on drilling the steam holes. With a head gasket, it's pretty easy.

DZAUTO

Doug,
For a factory head, the 487 is a good head.

INMYBLOOD

DZ I have 041 heads on my 350 I'm under the impression that they were also one of the better stock heads? Thanks Gordon

DZAUTO

Those are angle plug heads, right?
If so, they would be the earliest version angle plug heads, small chamber (about 64cc) and about the same size intake runners as earlier double hump heads (about 160cc). With a good port and bowl cleanup, they should be a pretty good head for a 350------------------------but a little on the small side for 400 cubic inches, plus, I prefer a 72-76cc chamber for a SB400 (for better compatability with today's pump gas).

INMYBLOOD

No straight plug, yes small double hump shape chamber the mark on the side is like a triangle maybe laying over on it's side. They have some work in them and it's only on a 350. Would they be too small for a 383? I'd like to do some motor work this winter and can't decide to build a spare short block to 383 or put vortec heads on my 350. I'm leaning towards doing a 383 for the torque and waiting until I can afford good heads down the road. Thanks Gordon.

DZAUTO

"Gordon,
Based on your info, I'd be inclined to build the 383 as you mentioned with the heads. The 041 heads would be somewhat marginal on a 383, BUT, with good cleanup work on the intake runners and bowls (and mild cleaning of the ex runners), they would really be a nice head.
I am not, and never have been a fan of GM's (production) heads AFTER the 1974 models. Beginning with the 75 PRODUCTION (SB only) heads, GM started cutting corners and by 77 they were just too thin and highly suseptable to cracking. I have zero problems with the Bowtie over the counter heads. I have ZERO experience with the Vortec heads because I have become a BIG fan of aftermarket heads such as Dart Iron Eagles. The last set of Iron Eagles I bought were for a SB420 and they had 215 intake runners with 2.05-1.6 stainless valves and guide plates.

Workin On 59

DZAUTO, what radiator setup are you using in your 56? I picked up a stock 60 radiator from a forum member for my 59. Do you think it will cool the 400 OK?

Thanks, Doug

glenn64vette

Great words of wisdom!
I've been building 400s since 88. Great engines, big block torque in a small block.
Use the longest rod that you can fit to the block for HP use. I use Scat 6 inch rods and at $285.00 (for 8) they are a steal. The rods are good to 750 hp and have extra clearance for the cam and block.
Just built my second 400 for my 64. The first one only lasted 19 years.

DZAUTO

Doug,
All my cars with a SB400 (except my 70 Chevelle) have a stock style radiator. My 51 chevy has a 5 bladed fan (for 55-59 pass cars with factory air) AND NO FAN SHROUD. My 56 Vette has the original radiator that needed a new core a couple of years ago. My son's 66 1/2ton pickup has the stock radiator/4 blade fan.
My 70 Chevelle conv was originally a 307 factory air car with a single row radiator. After installing the 400, I had my radiator man recore the original takns with a 4 row core. The Chevelle has the original 7 blade fan and fan clutch with a shroud. This is essentially the same cooling system that a BB Chevelle would have.
No problems with any of the above------------------------except, on VERY rare ocassions in the summer when stalled in traffic for an extended period with the 51 and the AC on, when the temp gets up to about 210, I turn off the AC comp clutch until moving again. The temp goes right down and I turn the AC back on.
The 420SB in the jet boat of course continually uses lake water---------------no worries there!