283 engine build

Discussion in 'High Performance Modifications' started by Indianajones, Jan 17, 2018.

  1. Indianajones

    Indianajones New Member

    Jan 17, 2018
    I have a customer building a 69 Z 28 clone. Brings me an engine allegedly out of a Corvette that he wants built to put in car. He knows nothing about the engine.
    His requirements are:
    Sound tough
    Squeal the tires when he wants
    Reliable and not have to work on it
    Yeah he is one of those types
    I tear it down and fine it is a .060 over 283 built between 1958-63. It has a steel crank, a set of old TRW L2302 high dome pistons, 3986336x steel heads with 76 cc chambers with double valve springs and a Crower baja beast cam with like .414 lift and 244 advertised duration.
    My biggest question is what would the compression ratio be with the piston/head combo? High dome piston but also a bigger chamber.
    All things considered, I want him to just build something different.
    Anyone have an opinion on what the squeeze would be, just looks to be too high for the street and pump gas.
    INDY piston 2.jpg 2.jpg
  2. Gary S

    Gary S Administrator Lifetime Gold Member

    Apr 14, 1999
    Bismarck, North Dakota
    Without doing any math on it, it would seem to me that any 76cc head will lower the compression of the engine from the old 302s. Back in the 60s, 283s normally had heads around 60cc and the 302s had heads around 64cc. Jumping to 76cc would drop the compression significantly from the 11 to 1 the 302s had, but you probably wouldn't want 11 to 1 anyway.
    Mwilson likes this.
  3. Turbo70Camaro

    Turbo70Camaro Veteran Member Gold Member

    Jan 7, 2005
    so cal
    walk away sounds like a nightmare waiting to happen.................
    Mwilson likes this.
  4. CorkyE

    CorkyE Veteran Member Lifetime Gold Member

    Nov 4, 2004
    Ringgold, GA
    ^^Good Advise^^
    Mwilson likes this.
  5. Skip Fix

    Skip Fix Veteran Member

    Mar 21, 2007
    302 was basically a 283 with a larger bore. Lots of circle track classes had 292ci(bored 283) class motors.
    If I was building a clone I'd use the new aluminum heads with the "camel hump" I want to think AFRs? Be a little easier to manage CR on pump gas and look authentic.Sell the iron heads! Find a correct intake, a Holley and then you get to cam choice. That will depend on which heads and CR you end up with. And if you want to risk a flat tappet solid or hydraulic going flat or retro fit a Hydraulic Roller and appropriate distributor gear.
  6. Indianajones

    Indianajones New Member

    Jan 17, 2018
    I agree but those engines used flat tops ?
  7. Gary S

    Gary S Administrator Lifetime Gold Member

    Apr 14, 1999
    Bismarck, North Dakota
    They used flat tops on the base 283 engines with lower compression. The high performance ones like the 302 and some of the early Corvette 283 had domed pistons.
  8. 70-camaro

    70-camaro Veteran Member

    Mar 25, 2010
    marietta ohio
    What abou a pair of 305 HO heads? 601 casting no. has 52 or 53 cc combustion chamber. Of course he would need different pistons.
    Last edited: Jan 17, 2018
  9. 70lt1z28

    70lt1z28 Veteran Member Gold Member

    Oct 3, 1999
    Beavercreek, Ohio, USA
    Those look like 12.5:1 pistons with a 64cc chamber. With a 76cc chamber figure around 11:1. Maybe a bit more. Too much for pump gas. You can cut some off the domes. I think that TRW used the same impact core for the 12.5's and 11:1's and maybe the 9:1 LT-1s. Measure the thickness across the dome. If so, you can easily just set them up in a mill and plane them off. With 76cc heads and a flat top you get 9:1 (71-72 LT-1 configuration). With about a 0.05 dome you would be in the 10:1 area. 70 LT-1 was a 0.100 dome and 64cc. 10:1 you can do pump gas.
  10. RS1979

    RS1979 Veteran Member Lifetime Gold Member

    Jun 18, 2013
    Memphis, TN
    My question is how much more can you bore a 283? To me 60 over is the max I'd run.

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