Stroker - piston sticks out of Cyl. 0.115"

Discussion in 'High Performance Modifications' started by rc3807, Apr 28, 2020.

  1. G72Zed

    G72Zed Veteran Member

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    I would measure everything up to see exactly what you have, including the blocks deck height. Hope they did not "over-cut" the blocks deck!!
     
  2. flht99b

    flht99b Veteran Member Gold Member

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    It almost sounds like it is a 3.75 stroke (400), they used 5.7" rods but bought pistons with the compression height of 1.560 from a 350. Stock 400 rods are 5.565" so there is .135".
     
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  3. 1980RS

    1980RS Veteran Member

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    If the rods are 5.7 replace one with a 5.65 rod and see if it's right height, if it is then you have the wrong pistons.
     
  4. 1320feet

    1320feet Veteran Member

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    Do you have part numbers of the rods and pistons they sold you?
     
  5. 76z28

    76z28 Veteran Member

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    I had this issue when I did my 383 in my corvette... Miscommunication with machine shop and with the deck they were .005 out of the hole... shot my compression up and had pinging issues.
     
  6. Plant Engineer

    Plant Engineer Veteran Member

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    .005" ? Hell . Thats damn near perfect for good quench. A .045" gasket and your'e golden.
     
  7. simso

    simso Veteran Member

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    I built a 383 a while back that had some piston pop of 8 thou above, they decked it just a smidgen low, thats an insane amount your quoting. From my early mechanics days (30yrs ago) 60 thou pretty sure was the ideal clearance between pistons and head, 40 thou is pretty close

    steve
     
  8. G72Zed

    G72Zed Veteran Member

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    I fully agree and second Plant Engineer's comments, I would say that's a good machine shop, that's the exact spec I use, +.005 with a .041 compressed thickness HG get's it in the "safe" sweet spot.
    It's one of those times that the added CR this gives actually helps in getting out of "pinging".

    Crank quality, rod material, piston alloy & pin height along with RPM mainly dictates how close you can go, or how close your comfortable with.
     
  9. oldchev

    oldchev New Member

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    Too Much!
    Everyone seems to be chiming in with lots of intelligent recommendations. They are all good.
    I didn't check your Summit head gasket, but if it were me I'd fix the issue and not patch it up with a oversize gasket.
    Something didn't go right somewhere. -N
     
  10. ZAMARROWER

    ZAMARROWER New Member

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    Well just trade those 400 pistons for correct 383 pistons if you had a decked block, and if anything else , you could shave the piston tops down just a little depending on ring land location and design of piston. what you need to do is check if the piston height from center of pin to top edge is 1.125" for 6" rod and 1.425" for 5.7" rod if the piston is taller 1.475" they are the short 5.65" rod 400 sbc piston. Now if you measure the pistons and know your rod length center to center , you can determine your block's actual deck height as it is measured. The crank is 3.75" and a zero deck is 9" while stock deck may be around roughly or even exactly 9.O25" at all 4 corners. You want a mls gasket that is anywhere from O.O39" to O.O40" and O.O41" This is the optimal size gasket, however if the pistons were only sticking up O.OO5" or so, then a O.O45" gasket would be the optimal choice. if you have 1.560" (350) pistons on a 5.7" rod and 3.75" crank (400) in a 350 it gives 9.135" and with a stock deck of 9.O25" (need to check all 4 corners) that gives the O.115" left over your talking about, Get some hypereutectic pistons or CP low expansion non gas port pistons that are 1.45O" and I can determine your CC if you tell me the Cubic Centimeters of your head's chamber. And you shall use the O.O4O" gasket. tell me what cam your using or I can recommend you one based on your Static Compression Ratio to get you pump gas drivability. You want a 64cc head with a slight dish. but we can get to that, let me know. With AFR 185cc comp cut head you'll have a huge torque 12 sec or less camaro you dont want 200 plus cc runner heads your only going to hit 12's with those in a street car cam and compression and rpm. You need ARP bolts on those 5.7" sbc 350 rods for sure. tell me what heads you have wether 882 or camel hump or whatever, it would be great if you could measure the chambers by cc'ing them.
     
    Last edited: May 7, 2020

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