350 Factory Piston Compression Height?

Discussion in 'Small Block Tech' started by MrSony, Nov 9, 2018 at 7:01 AM.

  1. MrSony

    MrSony Well-Known Member

    TA has the spec of 1.875 on their site, I didn't think it was that high, considering most of the aftermarkets are barely over 1.80. Anyone have any conflicting info?
     
  2. alec296

    alec296 i need another buick

    Replacement 340p is rated at 1.835
    Someone tryed to tell me that TA has their pistons custom made with more compression height. But still a 340p piston.
    Here’s summit racing link
    https://www.summitracing.com/parts/slp-340p30/
    The hyperutectic h522p pistons? Are rated at 1.855.
     
  3. 300sbb_overkill

    300sbb_overkill Well-Known Member

    Typically the cheap replacement pistons are shortened around .020" because they assume that people will have the block's deck machined that .020" when rebuilding. So, with the 1.835" 340P spec, it would probably be safe to say that the SP pistons would of been 1.855" from the factory?

    With the factory spec deck height of 10.187" with 6.387" rods and a 3.850" stroke would leave a 1.855" compression height piston .020" in the hole, add the .020" factory steel shim head gasket and that gives a quench distance(on paper anyway) of .040", right in that sweet spot!

    Unfortunately the factory left around on an average of .030" extra of deck height on the sbb 350 blocks vs the blueprint spec!:rolleyes:
     
    MrSony likes this.
  4. alec296

    alec296 i need another buick

    My sp engine the factory piston sat .058 below deck.
     
  5. 300sbb_overkill

    300sbb_overkill Well-Known Member

    So that block probably had an extra .038" of deck height on it, .058" - .020" = .038" probably? Sean76 claims that some of the later blocks have as much as .060" more deck height on them.

    Over the years all I have been looking at Federal Mogul as well as others that make "stock" replacement pistons they always have had .020" less compression distance that I would assume would be for deck milling to bring everything back to factory specs. To bad the factory specs suck! lol But mainly so the paint by numbers mechanics could set the timing according to the book as well as all the rest of the specs.:rolleyes:
     
  6. crouchmtrsports

    crouchmtrsports crouchmtrsports

    Most of the stock 350 pistons were around 1.852
     

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