Stroker Piston, Closed Chamber clearance

Small Block Mopar Engine

  1. SRT_DSTR15

    SRT_DSTR15 Well-Known Member

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    Now that Im looking to finally do everything correctly. I want to know if the 20.5cc pistons that come in the scat crank with Closed Chamber RHS heads will clear with .022 Head gaskets and Zero Deck. Im trying to find a piston that will give me 10.4-10.7 Compression on the street and still be able to run pump gas with a Cam that is .251-.257 @ 50.

    They offer the pistons in 20.5 cc and + 5.50 CC
     
  2. OLDSTYLE

    OLDSTYLE Well-Known Member

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    If your pistons are at zero deck .022 is not enough clearance. I like to see .035-.040 quench. Use .039 gasket and have heads milled to get your compression ratio.
     
  3. SRT_DSTR15

    SRT_DSTR15 Well-Known Member

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    I rather not have a 1 off set of heads. They were just worked on. I think that it might be easier to go with the .070-.075 thick gasket even if they are 120-150 :/


    The heads would have to be milled to 58cc from 64.5..Ill talk to Brian and see how much that changes the numbers.
     
  4. SRT_DSTR15

    SRT_DSTR15 Well-Known Member

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  5. MoparAnglia

    MoparAnglia Well-Known Member

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    Still zero deck? No. Way too much quench distance.
     
  6. rickstershemi

    rickstershemi It's True....I'm Nutz

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    I believe the OP intends to use this gasket with flat-tops in lieu of the 20.5 cc dished pistons....:glasses7:

    Rickster
     
  7. SRT_DSTR15

    SRT_DSTR15 Well-Known Member

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    If I used this gasket.. It would be with the 5.50 flat tops. Because If I didnt...Compression would be 11.8
     
  8. MoparAnglia

    MoparAnglia Well-Known Member

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    Compression ratio doesn't mean much if ya can drive between the piston top and chamber in a Peterbilt. Get the quench right and the motor will tolerate more compression. .075 gaskets are suited to pistons above deck IMO. Get the heads milled and set the right quench.
     
  9. OLDSTYLE

    OLDSTYLE Well-Known Member

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    20.5cc dish piston
    1008 FelPro gasket (4.18 gasket bore .039 thick)
    zero deck
    60cc combustion chamber

    Equals 10.4:1 compression
     
  10. SRT_DSTR15

    SRT_DSTR15 Well-Known Member

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    The motor is zero decked already.. Im pretty sure the pistons will be at least .005 above the deck with 5.50
     
  11. SRT_DSTR15

    SRT_DSTR15 Well-Known Member

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    whats the difference between a thinner gasket and milling the heads?

    If I dont have to mill the intake... I will mill the heads to get the compression I need.
     
  12. SRT_DSTR15

    SRT_DSTR15 Well-Known Member

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    I still have to see what the ABDC is of the cam Im getting because with the one I have right now, DCR would be around 9.3 which is not good at all
     
  13. 1wild&crazyguy

    1wild&crazyguy Banned

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    .022 is tight
     
  14. SRT_DSTR15

    SRT_DSTR15 Well-Known Member

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    Well I gotta talk to Brain for sure now, because the cam I have that i purchased has 50 ABDC and with any piston the DCR is to high for 91. I need something at least 67 ABDC to run 91, so I gotta see what he says because 50 ABDC and 10.6 SCR DCR is 9.34
     
  15. OLDSTYLE

    OLDSTYLE Well-Known Member

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    At zero deck the gasket thickness is your quench area .022 is to close when the rod stretches and piston rocks in the bore it will hit the cylinder head with a .039 gasket the quench is set at .039 so you mill the heads to the cc you need for the compression ratio you want. When you have the heads milled have them take a like amount off the intake side so the intake will line up.
     
  16. SRT_DSTR15

    SRT_DSTR15 Well-Known Member

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    I dont want a one off set of heads and Intake, that I will have to sell together if I ever do, but thank you
     
  17. ou812

    ou812 Well-Known Member

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    If you zero deck the piston at the little step it has, and run a felpro gasket and 62cc chamber you'll have 10.2:1.
    With that cam it'll be fine. Actual closing point on a 108lca straight up is 53.5 abdc. I've used it and it worked great on pump gas.
     
  18. SRT_DSTR15

    SRT_DSTR15 Well-Known Member

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    I thought when you cc the heads brian that they were at 64.5 no?

    Just want that number we talked about. And is that 53.5 the abdc on the new cam im getting or the one I have?

    Specs are

    62cc head, .038 gasket 10.249 SCR and 8.871 DCR
     
  19. 340sFastback

    340sFastback Well-Known Member

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    I run the KB forged step dish pistons and my Eddie heads are milled to get 10.3:1 compression with .039" 1008 Felpro gasket. I did not mill the intake side of the heads and had to mill the intake to fit cause I did not want to take the heads apart to mill the intake surface.
     
  20. 1wild&crazyguy

    1wild&crazyguy Banned

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    im running .035 quench distance...

    the int closing is a different story, one I was not commenting on...
     
  21. ou812

    ou812 Well-Known Member

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    The new cam. So you'll have even less with 64.5. Kick the cam forward 2° and call it good.
     
  22. SRT_DSTR15

    SRT_DSTR15 Well-Known Member

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    kk 53.5, advance 2 deg. at 55.5 and shave heads to 62.5 will give me 10.2 and 8.725 with .038 gasket

    and run 91 octane.. Thanks everyone
     
  23. SRT_DSTR15

    SRT_DSTR15 Well-Known Member

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    one last thing would a .028-.032 gasket. Is .038 the most quench anyone should run because of the forged pistons?
     
  24. ou812

    ou812 Well-Known Member

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    Before you buy a gasket, you need to mock the engine up with a rod and piston and see where it's at in the block. Do this before ANYTHING!!
     
  25. SRT_DSTR15

    SRT_DSTR15 Well-Known Member

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    Yes will do, just trying to figure which kit is best for what I want to do. Maybe the put together kit isnt right and I need to piece it together to get what I want?
     
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