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  1. #1
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    Dec 2016
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    Apple Valley CA
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    Real story behind BBC casting number10069286

    Yes this is a 1990 4 bolt main mark4 454 High performance block sold over the counter at gmpp. They were a 1 per person only. A crate engine outfit could not purchase one. In 1989 the gmpp guys where looking for new a headquarters out back of the GM. property. They went in an old building. And in a corner office that was Locked up they found all the thought to be lost forever casting molds ect... From the 1972 LS-7 454 that was suppose to come in 1973 stingray but didn't. They got the okay to cast 700 LS-7s ,they did some research and addressed the weakness's of the original block 10069286 is what they came up with The baddest toughest mk4 ever cast only one rated for 1000 plus HP only one with Siamese cylinders with 3 1" slots machined between cylinders for coolant flow, only one w/ 5/8 shanked main cap bolts, wich by the way mine has CAT bolts. When they were done R and D came and took there modified mold and formulas for research and the new generation 5 and 6 eng. Are based off of 10069286 wich kinda makes it the grandfather of the new 572 crate motor and all gen 5 and 6 blocks. I read this in an early 90 S copy of hot rod magazine.

  2. #2
    Join Date
    Oct 2011
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    ft pierce fl
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    when gm brought back the Ls6 and Ls7 motors in the late 80s or early 90s the motors were built in mexico and were not anything to be proud to own. the Ls6 came with alum intake and cost 100 more than the Ls7 that came without intake. Ls7 12.5 compression. Ls6 10.5 compression. i have never seen one run 10 hours before it pulled valve locks thru the retainer. the Ls7 with aftermarket valve springs and retainers did make decent track motor that would run mid 11s to high 10s in a 3000lb nova or camaro. ls7 cost around 2200 in the early 90s and did creep up in price over the years to about 2600.

  3. #3
    Join Date
    Feb 2004
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    Palm City Fla
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    Chaz = thinkin iron makes for good farm equipment ...


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