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400 SBC rebuild recommandations

Discussion in 'GM Powertrain' started by bowfishrp, Jun 2, 2009.

  1. bowfishrp

    bowfishrp New Member

    Not sure if this is the right place or not....

    About to rebuild a Chevy small block 400 and looking for advice. I know the engine has a ring problem and a bunch of miles on it so my plan was to tear it completely down and rebuild the lower end to stock other than rings and probably upgrade the pistons for lighter weight. Hopefully I wont find any major issues. Will be replacing all the bearings and will have the block fuxed and bored if needed. Basically everything else will be cleaned and reused if possible.

    My plan is to put alum heads on it and am leaning toward Edelbrock but might go with Brodix or possibly Jeggs or Summit brands because of their price. Also not sure if I want 64cc or 70cc chambers. I am not as concerned about HP as I am weight. Already have an Edelbrock alum intake and a 650 carb (Edelbrock or Holley.) Will get a different cam and new timing chain.

    This engine will go in a jet boat but wont be racing or trying to do high RPMs or MPHs. I am looking for low-mid range with good idle and decent fuel mileage. I figure it will push the jet with too many upgrades.

    I am looking for advice for SBC rebuilds. Again looking for low to mid range and dont plan on running over 4500 rpms.
    Thanks for any help
  2. grimreapersshadow

    grimreapersshadow Rockstar 100 Posts

    i have edelbrock heads on my 350 and im crankin out over 400 hp/torque at the rear wheels but i got alot of other mods on my engine also the 64 cc heads will be more freindly on pump gas the 70 cc heads will want more fuel and higher octane for best performance and alot will depend on the compression ratio/ what kind of pistons your using good area for best of both would be a compression ratio around 9.5:1 and lower also the edelbrock intake will match up best with the edelbrock heads as they are matched for each other
  3. leadpan101

    leadpan101 Rockstar


    Sound like a good idea in general, but i wouldn't use summit or jegs brand heads, you get what you pay for with heads. i would look at summit or jegs, for a head, cam package that suits you needs.
  4. bowfishrp

    bowfishrp New Member

    Thanks guys. Tore into the block yesterday and a couple cylinders look pretty bad. It has been sitting a while in the rain and they are rusted. Unfortunately it is not surface rust. I might be able to get it bored out to clean it up but I need to weigh that against the prices I am seeing for a complete 350 short block.
  5. Z71_guy

    Z71_guy Epic Member 5+ Years 1000 Posts


    thats where im at in my built, waying cost, i have a 350 4 bolt main and one of the caps was cracked so i have to get it line bored with new caps or get a new try a differand block and see whats inside
  6. bowfishrp

    bowfishrp New Member

    Found a few 350 shortblocks from $525 on up but some of them wont take a 400 as the core.

    The machine shop said it would be a little over $200 for what I need done but they need to see it to tell me if they can even bore it out or not. Since a cheap engine rebuild kit runs around $300 I am thinking I will take the block over to the machine shop and see what they say.

    Worse case the cylinders are trash and it is a large paperweight BUT I have a 400 crank so might get ahold of a 350 block and build a nice little 383. Really want it to be ok. I will post up some pictures once I get them off the camera.
  7. gocubs68

    gocubs68 Member

    if it is still a virgin block, you should be okay as far as re-using your 400 block. if i remember correctly, most 400 blocks are 2 bolt mains, if they are, I would see about getting your block drilled and tapped for splayed main caps. for your application this thing will probably see a constant 4-5k rpms frequently. wouldn't hurt to add a little strenght to your bottom end, I would also consider a main cap girdle. just something to think about.
  8. bowfishrp

    bowfishrp New Member

    Thanks for the idea...something to be considered. I dont think I will be running over 4000 rpms much though....this will be a jet boat but it wont be racing and it is not your typical jet boat.

    Was looking over the cylinders last night and they might not be all that bad. Will be pulling the crank this weekend and try to get it to the machine shop early next week.
  9. gocubs68

    gocubs68 Member

    well, at the least, if it's a 2 bolt main, i'd look into a main cap girdle. pretty cheap for the added strength.
  10. bowfishrp

    bowfishrp New Member

    Good news. Got the block stripped down and those two cylinders dont look as bad as I first feared. They will still require a bore but I dont think it is near as deep a rust problem as I thought.

    Crank needs polishing in the least because it has some rust too. Machine shop will like me. :)

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