PDA

View Full Version : 400 Cu.In. Small Block Chevy?



silverghost
03-13-2010, 06:24 PM
I am still in the market for a powerplant for my "Benchseat 18" project.
A local gas station mechanic/owner has been trying to sell me a 400 Cu.In. Small Block Chevy engine for $1800.
Basically a 150K mile stock Impalla rebuildable core that has been sitting inside since he pulled it out of a car he junked years ago.
I had heard all sorts of horror stories about the small block 400 in it's day with leaking head gaskets ,& steam pockets etc. In their day head gaskets were a real issue.The Chevy 400 was not on the new car market very long.
It is tempting to think about this as a rebuilt & slightly over-bored 400 which would almost give you the displacment of a 454 Big Block with much less weight & size.
What are your opinions on this 400 engine?
Are they hard to find these days?
What about his $1800. core price.?
Is there a supply of good high performance bottom end parts out there for the 400 ?
ie; Forged steel crank, rods, pistons etc.
It seems to be an interesting idea~
What are your thoughts?
Thank's

BUIZILLA
03-13-2010, 07:22 PM
$300 for the rebuildable core

you can make a great engine out of that...

thehow33
03-13-2010, 07:35 PM
I think a 427 sounds nicer than a 400 :wink:

vlbob2
03-13-2010, 07:46 PM
Why don't you buy a brand new crate engine 383 ci sbc out of JEGS for $3295, brank new! Cast iron vortec heads. Then add whatever marine parts you want. Or full dress $4195, and put it in the boat.Also, Read Small Block Chevy Marine Performance by Dennis Moore. Good Luck, Bob

BlownCrewCab
03-13-2010, 09:36 PM
isn't forrest's engine still for sale for $2500? You can still find rebuildable 400's for under $500. if you decide to build one be sure to step up to (at least) 5.7" con rods. Build the best bottom end you can. if you drill the steam holes in the heads then the steam pocket thing isn't an issue. with a good cam and some flat top pistons the 400's are torque monsters, and if you build a good bottom end then you can rev it like any good smallblock and get great top speed #'s. if you do go this way I'm sure Buiz will have allot of input & I Have done a few Killer 400's myself. any questions just ask.....

Pismo
03-14-2010, 06:46 AM
You are right. The 400sb had heat issues that lead to warping/head gasket issues and it's general overall unreliability and discontinuation after few years. Avoid it, build a 383 instead. There are lots of 350 re-buildable cores around to do that. Many more parts, more reliable, you'll be starting from a better and much more common foundation with many more options.

ITTLFLI
03-14-2010, 10:42 AM
be sure to step up to (at least) 5.7" con rods. ...

Make sure you use the correct rod bolts if you use the 5.7" rods...clearance on the cam is the issue.

BUIZILLA
03-14-2010, 10:52 AM
I have a destroked 400/395 in a crate.. 4.165/3.625

try finding shelf pistons for that combo... :nilly:

i've had it well past 8,000

real happy at 7400

mrfixxall
03-14-2010, 11:50 AM
Why not do something different! read this first then you can decide..

http://www.chevyhiperformance.com/techarticles/0603ch_gen_iii_engine_block/index.html

Cuda
03-14-2010, 04:03 PM
Chebby has been making the SBC since 1955.

Christian
03-15-2010, 12:50 AM
i am building 2 388" SBC now for the race boat

will be plenty of power for a 30' 3 man with the right parts

i would pass on a 400 SBC that i didnt know what was going on with it.

Whats your project look like, havent seen or read any updates??

really dont know how your boat is going to run with the hull and balance being different. I would start off easy instead of wanting to make speed runs 1st time out.

good luck

Chris from NJ

Rodger
03-15-2010, 08:24 AM
I built a SB 406 back in 1983 for my 16' Donzi. I used the original crank & rods but installed forged TRW pistons (+.030) with a nice cam, heads, & 650 Holley. We had a couple of 18's on our lake with original 454/330 TRS setups. My 16 with the 406 had absolutely no problem pulling away from those guys. No GPS back then... therefore I can't give any accurate MPH. I kept the RPM limit to 5000 and had no problems. I was aware of all the negative stories on the SB 400 but I didn't experience any of that on my rebuild. I ran that engine in the boat for ten years before installing it where it currently is...my 64 Chevelle. It has not been disassembled yet after 27 years. In the boat I logged about 500 hours on it and in the Chevelle about another 70,000 miles. So as you may guess, I won't discourage you from building a SB 400.

MOP
03-15-2010, 09:22 AM
There is nothing wrong with building a 400-406, sure drill a few holes to eliminate the steam issue though I have seem several without that did just fine. Most of you all worry to much they hold up fine and are a very cheap way to grab some cubes, A good cam some decent heads and you have a reliable torque monster.

joseph m. hahnl
03-15-2010, 02:37 PM
4.125 in bore family (1970-1980)

400

The only block of this family, 400 cu in (6.6 L) small-block, was introduced in 1970 and produced for 10 years. It was loosely based on the medium journal 350 and had a 4.125-inch (104.8 mm) bore and a 3.75-inch (95.3 mm) stroke. The 400 differed from other small blocks in that the cylinders were siamesed, used a 2.65” large journal, and often times had one more freeze plug on both the left and right sides of the block. Initial output was 265 hp (198 kW) and was only available equipped with a 2-barrel carburetor. In 1974 a 4-barrel version of the 400 was introduced, while the 2-barrel version stopped production in 1975. 1976 was the last year that the 400 was used in a Chevrolet Passenger car, available in both the A-Body and B-Body line. While popular with circle-track racers, the engine was prone to cooling troubles if cylinder heads without steam holes were used. They mostly put out 250 hp stock. Due to the way the block was designed, the 2 bolt main engines were stronger than the 4 bolt versions if properly prepped. The 509 2 bolt main block is the most desirable 400 block

The following is based on opions of others. It does not necesarily reflect fact

(1)Siamesed cylinders are those that have no water jacket between them...making them prone to overheating, especially when bored out. Normal cylinders have water jackets between them to help on cooling of the combustion chamber, and the friction caused by the pistons. Most siamesed cylinders have sleeves for replacement, but not always


(2)A 400 Chevy ends up having the center two holes on each side siamesed.
Meaning that the center two cyl have no water jacket in the middle or between each other.
This causes a problem with them egg shaping easy under alot of power. Since the sides with out water jacket don't flex with the explosion... they dont' move and the one's with do.. thus egg shaping the cyl.

jbowen60
03-17-2010, 08:23 PM
Whats the best cam for a 383 or 400 marine SBC?

MOP
03-17-2010, 08:27 PM
We need "Mad Dad" to chime in on this, he has been running a hot 400 for about 3-4 years now and shows it no mercy!

mrfixxall
03-17-2010, 08:29 PM
Whats the best cam for a 383 or 400 marine SBC?


Call Bob mandara @ marine kinetic's.585-654-8583