L2307af 4.270 ?

Discussion in 'High Performance Modifications' started by ss monte, Apr 9, 2009.

  1. ss monte

    ss monte New Member

    11
    0
    Mar 31, 2009
    pontiac michigan
    Big Problem Im Putting Together A 454 Bbc High Comp Motor Im Using Or Was Going To Use A Trw L2307af 30+ Piston. Block Is Bored 30+ 4.280 I Bought These Through Ebay Nos Pistons They Looked Great. Untill I Went To Check Bore Clearence And Found Out That After I Miced The Pistons They Are 4.270 0,005 Under My Minimum Recomended Specs. Trw Says They Cant Be More Than 0.0055 Clearence Wich Means The Pistons Have Got To Be 4.750 Could They Have The Wrong Pt# Stamped On Them. They Are Probley At Least 10 Yrs Old But They Were Nos If Any One Could Give A Clue Of Just What This Piston Is Thanks Looks Like I Will Be In The Market For New Slugs Ss Monte
     
  2. ss monte

    ss monte New Member

    11
    0
    Mar 31, 2009
    pontiac michigan
     
  3. 74RAT

    74RAT Veteran Member

    3,400
    0
    Dec 28, 2003
    ft. stockton,tx,usa
    i am using that piston currently in .060 over. L2307AF60 speed pro version of TRW. has .580 dome. has graphite coating on the skirts. mine are in at .006 clearance.

    sounds like a box of seconds you may have there,, or ones that couldn't be sold in the past,, for just your reasons. either new pistons,, or bore/hone a block to fit those pistons.

    if you use them,,, make sure those skirts haven't been collapsed,, or been dropped or something like that.

    do they all mic that small from the top of skirt to bottom of skirt? should be about .002-.003 skirt taper from the skirt tips to the top,, just under the oil ring land. forged pistons have more skirt taper for the increased heat expansion of the piston head/crown area compared to a cast or hyper.

    mine measured .0055 under the nominal oversize at 90* to the base of the lower pin bore support area...... and recommended that for clearance. i used .006 clearance.
    andy
     
  4. 74RAT

    74RAT Veteran Member

    3,400
    0
    Dec 28, 2003
    ft. stockton,tx,usa
    trw says they can't be LESS than .0055 clearance. they'll seize up in the bore. just to clearify. that's a minimum clearance listed.
    andy
     
  5. ss monte

    ss monte New Member

    11
    0
    Mar 31, 2009
    pontiac michigan
    Yes They All Are The Same These Look Brand New They Still Have The Maching Grooves On The Skirt The Skirt Is Not Coated So There Over9 Years Old I Think Im Screwed My Block Has Allready Been Bored Big Mistake Not Having Pistons In Hand Befor Boring Ss Monte
     
  6. 74RAT

    74RAT Veteran Member

    3,400
    0
    Dec 28, 2003
    ft. stockton,tx,usa
    pistons are someting i'll only purchase from the mfgr or a reputable reseller. not a one time shot type company.

    if it were me,, i'd go after that dude and get your money back,, then go through a reputable dealer so you get a piston set that mic's out correctly....... jmo.
    andy
     

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