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Fuel Type

Discussion in 'The Garage' started by grindkings, Jan 13, 2005.

  1. grindkings

    grindkings 1/2 ton status

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    I'm building my engine. 350, .60over. Dish pistons, Holley 670cfm TBI with Projection manifold. Valve job and big cam. Possilbe fatter head casket for more compression. What type of fuel should i run. I'm
     
  2. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    probably 91 , depends on overall compression ratio and total advance :k5: :k5:
     
  3. Thunder

    Thunder 3/4 ton status

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    Big Cam??? is it computer friendly? Need a custom chip to run a big cam with TBI
    Fatter head gasket with dished pistons?? That will lower compression ratio a lot. Stock CR. is 8.2 to 1. Putting in a fatter head gasket will lower the CR even more so 85 octaine should be fine.
    I hope you aren't building this engine for performance.
     
  4. grindkings

    grindkings 1/2 ton status

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    say what know? You said a fatter head gasket will lower compression. I thought it would up it.
     
  5. loafer

    loafer 1/2 ton status

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    Fatter head gasket = lower compression ratio

    CR= (volume @ btc)/(volume @TDC)
     
  6. grindkings

    grindkings 1/2 ton status

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    so how can i raise compression without differnet pistons?
     
  7. Silver84k5

    Silver84k5 1/2 ton status

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    heh, well lets see. since a fatter head gasket lowers compression, i bet you a thinner gasket ups your compression.. plus get some flat top pistons, not dished,

    With aluminum heads you can get away with 10.5 :1 compression and run pump gas (91)

    with Steel heads you can get away with 9.5 :1 maybe a little more, and still run pump gas.
     
  8. grindkings

    grindkings 1/2 ton status

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    I already have my pistons. But i went down to the AutoParts store and Orderd a thinner head gasket. Think i'll need a different ignition?
     
  9. big_truxx

    big_truxx 1/2 ton status

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    I liked the accel ignition I had once apon a time. Made a difference.
     
  10. dirtwarrior17

    dirtwarrior17 Banned

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    Where do you buy your gas? 85 octane in a high comp motor won't do it( didn't even know they made 85)

    I have the same setup as you but with 10:1 flat tops and modified camel hump heads, also have a 45 psi fuel pump( the stock pump will not feed that much hp). You will definitly need to run 91... maybe 89 but underload it will ping. A custom chip is CRITICAL to your power gains... without one all those performance parts are useless. Don't forget some headers and good exhuast.
     
  11. sweetk30

    sweetk30 professional hooker Premium Member

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    try the gm factory shim gaskets . thay are the factory type and are the thinest i know of for street motors. thay hold up all day for about 100k miles at least on dd vehicles. also have the heads shaved and recheck the intake gasket angles also if shaving the heads . so you dont have gasket leaks.
     
  12. smalltruckbigcid

    smalltruckbigcid 1/2 ton status

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    What kind of quench distance will you have? Less than .035 will cause problems. How far down the hole are the pistons? Thats sometimes refered to as deck height. If you don't know these answers get this book by David Vizard How to build a Max performance small block chevy. The problem in not knowing those factors is when you go to a higher compression do the valves hit the pistons. To tight or to loose of quench and the engines is prone to detonation problems regardless of the fuel.
    George
     
  13. grindkings

    grindkings 1/2 ton status

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    Thanks.. I did mean linner head casket. WIth that gasket, dish pistons(.60), Comp Cam extreme 4x4 cam, nice TBI unite. and chip. What compression shouldi be expecting.
     

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