'76 Buick 350 Head Shim

Discussion in 'Small Block Tech' started by Seven6Regal, Sep 16, 2018.

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  1. Seven6Regal

    Seven6Regal Active Member

    Good morning V8Buick,

    I've been researching ways to increase compression without breaking the bank. I've also decided to go with Comps 268H which supports up to 9:1 CR. The engine is still stock except that I've started the intake swap and realized the factory carb has thermal choke. I'm waiting for choke to arrive. Anyway, back to my point.

    I've searched high and low for a head shim for this engine and cannot seem to find one. Any ideas where to find the correct shim? Thoughts on milling? I'm current running premium / high octane because the engine would knock with 87.

    Planning to order cam tomorrow to replace lifters and timing chain too while I have the intake off. Thanks for any response.
     
  2. 300sbb_overkill

    300sbb_overkill Well-Known Member

    There are WAY better cams available than the Comp 268 for a sbb 350 that was actually designed for a sbb 350.

    What's a "head shim" are you trying to say steel shim head gasket? Check TA performance, they should have everything you need for your Buick engine.
     
    alec296 likes this.
  3. alec296

    alec296 i need another buick

    If your talking about the 68-70 steel shim head gasket, it will not work on a 76 head without plugging the center coolant scallops . Then having head milled smooth. And with the low 7.7 compression on the 76 engine , .020 will only net 7.99. Piston sits .090 below deck. That’s the compression problem. I have heard people have decent luck with that 268 but I prefer the crower cam. Maybe degree the cam 4 advanced to increase dynamic compression alittle.
    If your getting knock on a low compression engine you have a problem, not cooling right, timing issues, or lean carb/vacuum leak.
    The 1734 3.0 v6 pistons would net 9.65 and still be down at .090 below. I would change piston either way. And change the front cam bearing with a new cam.
     
  4. Seven6Regal

    Seven6Regal Active Member

    Yep. I'm talking about the steel shim head gasket. TA has copper, I haven't contacted them yet.
     
  5. Seven6Regal

    Seven6Regal Active Member

    The 268H is one that was recommended on this site by others and the price point is affordable. I have my engine torn down and would like to get a few more drives in before the winter hits. A piston upgrade is possible over the winter as well. I will post updates as they happen.
     
  6. UNDERDOG350

    UNDERDOG350 350 Buick purestock racer

    Don't base your parts selection on price. That never works. Use the Crower Level 2 for a near stock compression engine. Change at least the front cam bearing when replacing the cam.
    For the steel shim type gasket to seal properly both the block and head surfaces need to be perfectly flat and straight. In other words freshly machined. If you are getting knock now you have some type of problem to sort out first.
     
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  7. Seven6Regal

    Seven6Regal Active Member

    Which level 2 do you recommend?
     
  8. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

  9. UNDERDOG350

    UNDERDOG350 350 Buick purestock racer

    Thanks Larry. That is the correct cam. Also use Crower lifters so there's no material/heat treat mis match. And use the recommended springs.
     
    MrSony likes this.
  10. hugger

    hugger Well-Known Member

    Just wait and do it once, spending money and time on stuff that will net 0 performance increase isn't beneficial. Just call it an early year and get to work gathering info and parts and come out next spring with a solid 350hp engine.

    Pull the engine , doll up the engine bay while you accumulate the parts. Address all those other little nagging issues it has then when you get it back out you will have forgotten the 2months early it went out of service
     
  11. alec296

    alec296 i need another buick

  12. Fox's Den

    Fox's Den 22 years of racing the same 355 Buick motor

    That 268 cam is from 1983 that is how old it is I would go with something different.
     
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  13. Seven6Regal

    Seven6Regal Active Member

  14. alec296

    alec296 i need another buick

    If you plan to do a piston change soon, I would leave cam alone for now, and when you change pistons, get the crower 50258. It will be the next one up.
     
    300sbb_overkill likes this.
  15. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    It's REALLY important that you read and understand this article.

    http://www.empirenet.com/pkelley2/DynamicCR.html

    If you don't, you could actually make your car slower. Cams don't automatically give you more HP unless you match them to the engine's static compression. With low static compression, you are better off with a smaller cam.
     
  16. UNDERDOG350

    UNDERDOG350 350 Buick purestock racer

    The level 2 would work better with your low compression. If you are over 9:1 then you can use the level 3.
     
    300sbb_overkill likes this.
  17. Seven6Regal

    Seven6Regal Active Member

    I ordered the level 2 (should be here Wednesday), installed the eBay Poston S-Divider, converted the choke to electric and replaced the thermostat (old one stuck open). Upper radiator hose had very little to no pressure after idling for about 10 minutes. A trip around the block and my face is hurting from smiling ear-to-ear.

    I'm planning to change the water pump, front cam bearing, oil pan gasket and rear seal and repair the AC to complete the engine work.

    Thanks for the info.
     
  18. MrSony

    MrSony Well-Known Member

    TA sells the dual groove hardened cam bearing (1) that you will need. Depending on your oil pressure, I'd get an oil pump kit, wear plate, and regulator, if you haven't yet.
     
  19. MrSony

    MrSony Well-Known Member

    Use a ford 460 big block rear main seal (from a 90s ford pickup or something at the parts store), it drops right in. I used RTV liberally instead of the side seals. TA's side seals actually fit in the pockets. If you still have a qjet, it may not like the bigger cam. It's not much bigger than stock, so you should be fine. I liked my 8:1 buick 350. Liked 12* with the comp 268 it had. I will always trade a little compression for a little more timing on a street engine.
     
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