Results 1 to 11 of 11

Thread: 400 small block chevy

  1. #1
    Join Date
    Sep 2008
    Location
    St. Marys, WV
    Posts
    618

    Default 400 small block chevy

    My dad and I recently purchased a 79' motorhome that had a 400 small block chevy engine in it with 400turbo tanny in it. I was wandering what we should do with the motor... We are just using the motorhome as a cabin. I would like to take time and build it and put it in something to play around in, but is the motor worth anything. It runs good and only has 30,000 original miles on it. I was wandering how expensive it would be to build or if i should just try to get some money out of it... when i looked the specs up, it was less than 200hp but a good bit of tq... let me know what you guys think...
    2011 Silverado 1500 LT 4x4 Crew Cab, 7.5" Rough Country Lift Kit, 20" Eagle Alloy Wheels (superfinished), 35x12.50x20 Federal Couragia MT, Innovative Creations Chrome Nerf Bars, AVS Vent Visors, LineX Spray in Bedliner, Rugged Tri-Fold Tonneau Cover, Bushwacker Pocket Style Fender Flares

  2. #2
    Join Date
    Aug 2005
    Location
    Clarksburg, Wv
    Posts
    4,986

    Default Re: 400 small block chevy

    Quick swing through a web page got this:


    Some 400 hot rodding tips:
    Getting the 400 to really perform, especially for the street, is not hard to do, it just takes a little planning and common sense. The biggest issue with getting the “power” out of the horsepower is the size of the engine. 400 cubic inches need a lot of air to make big numbers. I recommend starting out, after all the block machine work, with a good pair of heads, ones that have very good flow characteristics, big valves, large intake runners with 200 cc volume or more, and in the case of the 400, steam holes to match the ones in the block (remember the overheating?). GM performance has a selection of excellent heads that will make exceptional power and torque. Intake manifolds that create high velocity will work well. GM also has an excellent selection of excellent intakes. I have found that the old style Z-28 or LT-1 intake manifolds work very well for the street. High velocity is the main goal. It is easy to make over 500 ft-lbs of torque on 91 octane gas…just remember when considering pistons and combustion chamber volume, to keep the compression ratio less than 10.5 to one or you will have detonation problems. As for camshafts, a reasonably “smooth” cam with around .480 in lift and 260 deg. duration will work well, and will idle with good vacuum. There are virtually hundreds of camshafts that can be used. Do a little research and comparisons keeping in mind the RPM range that you will be using most, and pick the best hydraulic cam from there.
    Just remember, a small block 400 (406 with .030 overbore) can be a real street performer with loads of torque that will melt your tires .But keep it cooled, spend some bucks on a good radiator with an electric fan set up, and you can’t go wrong!
    I did a quick search and found Greg's Engines in OHIO. They show you with pictures how you can take a good set of good flowing 350 heads and make them fit the 400. This is a great idea becase the 400 heads tended to crack and are becoming harder to find. The other alturnative is to buy a set from GM Performance.
    In any case the 400 Small Block Chevy can be a awsome motor for you hot rod! I have enjoyed many of them over the years.
    09 Sonata (My DD)
    92 C1500 ( Winter Beater/ Hauler)


    07accord - "I want to be a nittany lion!"
    "I'm pretty sure I have no fam. in South Jersey.Real mullet fairing people don't have spray tans." Levilz


  3. #3
    Join Date
    Mar 2009
    Location
    Hurricane,WV
    Posts
    344

    Default

    I ve seen and rode in a few cars with built 400s . The torque is awesome. I have on in my shed that I hope to build one day.

  4. #4
    Join Date
    Aug 2007
    Location
    Parkersburg, WV
    Posts
    2,998

    Default

    The 400 is a good engine. You don't come across them very often any more.
    - I break things -
    '70 Mach-1 "money pit"

  5. #5
    Join Date
    May 2011
    Location
    Kingwood
    Posts
    313

    Default Re: 400 small block chevy

    I have run a bunch of 400s, good cam and heads make em torque monsters. Being in a motor home I would atleast pull the heads, I have seen a bunch crack between the cylinders in heavy load applications. As said they are getting scarce and a good runner is worth pretty good $$.

  6. #6
    Join Date
    Sep 2008
    Location
    St. Marys, WV
    Posts
    618

    Default Re: 400 small block chevy

    thanks for the replies... i'm going to try and do a little more research on this, and i'll keep it upadted what we will be doing with it...
    2011 Silverado 1500 LT 4x4 Crew Cab, 7.5" Rough Country Lift Kit, 20" Eagle Alloy Wheels (superfinished), 35x12.50x20 Federal Couragia MT, Innovative Creations Chrome Nerf Bars, AVS Vent Visors, LineX Spray in Bedliner, Rugged Tri-Fold Tonneau Cover, Bushwacker Pocket Style Fender Flares

  7. #7
    Join Date
    Dec 2007
    Location
    harrision co wv
    Posts
    766

    Default Re: 400 small block chevy

    there good engines you can use any sbc heads but got to drill the coolent steam holes in them lay a 400 head gasket on them and drilll the holes needed vortecs work real good on street engines there in 96-01 chevy trucks and vans with the 350 great low end power if u want to rev it over 5500 u need 350 5.7 inch rods and aftermarket pistons . the later blocks were stamped 509 and has 2 freeze plugs on the side the earlier ones had 3 the later 509 blocks are more durable i think yours is rated at 180 net hp but definally can be uped to over 350 cheaply
    JPrice

  8. #8
    Join Date
    Aug 2005
    Location
    Arnett, Raleigh Co. WV
    Posts
    1,617

    Default Re: 400 small block chevy

    GM really nutted those engines in the 70's with all the emissions requirements going on by the Gooberment. If I remember right they dropped the compression ratio way down, and the cam was just enough to get the engine to run. Give the engines some compression, let them breath, and they can be great performers. I think the 400's had a 4.125" bore? Sound right Josh?

    Having Cameron as a site rep is like having a retard as a mascot.

  9. #9
    Join Date
    Dec 2007
    Location
    harrision co wv
    Posts
    766

    Default Re: 400 small block chevy

    yea thats the rigtht bore size with a 3.75 stroke around 8 and 8.5 compression with 76 cc heads that were crap for performance with that low milage should be able to re ring it put some good heads and cam and make a good engine for not a lot of cash
    JPrice

  10. #10
    Join Date
    Mar 2009
    Location
    Hurricane,WV
    Posts
    344

    Default

    My budget plan for mine (509 casting) was to clean up the bores, re ring it and install new bearings and maybe have arp rod bolts installed. I have some aluminum gm phase 6 heads I have that are brand new. They are in the machine shop now up home. For a cam was going with a comp xtreme grind .

    Just haven t really got into it yet. And I have been holding out in case I come across a forged rotating assembly cheap with 5.7 rods. (doubtful)

    I am sure in with the stock short block I would be more than happy with all the torque . I just hate being rev limited.

  11. #11
    Join Date
    Sep 2008
    Location
    St. Marys, WV
    Posts
    618

    Default Re: 400 small block chevy

    awesome... leaning towards a project right now... it will still be a couple weeks before we pull it to see what i'm actually working with...
    2011 Silverado 1500 LT 4x4 Crew Cab, 7.5" Rough Country Lift Kit, 20" Eagle Alloy Wheels (superfinished), 35x12.50x20 Federal Couragia MT, Innovative Creations Chrome Nerf Bars, AVS Vent Visors, LineX Spray in Bedliner, Rugged Tri-Fold Tonneau Cover, Bushwacker Pocket Style Fender Flares

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •