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Technical SBC327 250HP vs 300HP in 1962

Discussion in 'The Hokey Ass Message Board' started by jhutch, Feb 27, 2017.

  1. According to the Corvette Black Book, both had Carter's but the 300hp was Aluminium (AFB) instead of WCFB.
    Intake manifold 250 hp - #3783244, 300hp -379349, both cast iron. Heads: 250hp - 3795896 & 30hp - 3782461. Exhaust manifolds 250hp - 3749965L & 33750556R, 300hp - 3797901 L & 3797902R.
    Corvette Parts Book shows they have the same cam, pistons and crankshaft.
     
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  2. DDDenny
    Joined: Feb 6, 2015
    Posts: 18,987

    DDDenny
    Member
    from oregon

    I think they were testing the waters with that 300 horse engine (hydraulic lifter), the 327/350 hp (hydraulic) was on the drawing board at the same time.
     
  3. 6narow
    Joined: Jun 1, 2008
    Posts: 555

    6narow
    Member

    So you're saying you're in agreement with me?
     
  4. squirrel
    Joined: Sep 23, 2004
    Posts: 55,644

    squirrel
    Member

    I'm saying they can easily get either 250 or 300 hp out of an engine by changing the heads, intake, carb, and ex manifolds, without changing the cam.
     
  5. Dan Timberlake
    Joined: Apr 28, 2010
    Posts: 1,522

    Dan Timberlake
    Member

    From Chevrolet's 1955 SAE paper about the "Chevrolet V8 engine."

    Presumably just adding a 4 bbl carb and dual exhaust.
     

    Attached Files:

  6. 6sally6
    Joined: Feb 16, 2014
    Posts: 2,431

    6sally6
    Member

    (Coming from a Ford dude) I always thought top HP for a 327 FI was 375
    HP for 327 non FI was 365.
    I been worng for 60+ years ?!
    6sally6
     
  7. squirrel
    Joined: Sep 23, 2004
    Posts: 55,644

    squirrel
    Member

    The ratings changed over the years. FI engines 62-63 were 360, 64-65 were 375.
     
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  8. DDDenny
    Joined: Feb 6, 2015
    Posts: 18,987

    DDDenny
    Member
    from oregon

    This Chevy guy learned not to venture too far into a blue oval discussion!
     
  9. lippy
    Joined: Sep 27, 2006
    Posts: 6,822

    lippy
    Member
    from Ks

    If I was GM and I had a 275 horse engine in a station wagon and a 300 hp engine in an impala hardtop I would tell you your impala hardtop had the NEW 300 horse engine with the big exhaust manifolds and was the hotter setup. If you don't believe us, just drive the lighter impala hardtop. ;)
     
  10. lippy
    Joined: Sep 27, 2006
    Posts: 6,822

    lippy
    Member
    from Ks

    The horsepower wars were BS. I have owned a 300 327 in an impala and I have owned a 300 Horse (295) horse 350 in a 69 camaro, The impala was a 4 spd, the camaro was a 4 spd. Different cars, different gears, different everything. Not hard for them to lie. And it doesn't matter. Just pick your GM number for a certain cam, put an AFB or quadrajet on it and grab the best heads, doesn't matter it will all boil down to how saavy an engine guy you are. Nite nite.;)
     
  11. lippy
    Joined: Sep 27, 2006
    Posts: 6,822

    lippy
    Member
    from Ks

    Actually there probably was no difference in the engines if they were close in years. But your girlfriend didn't know that. ;)
     
  12. 6narow
    Joined: Jun 1, 2008
    Posts: 555

    6narow
    Member

    Yes, I agree with that statement, but if you look at the specs, the 300hp engine's power peaks happen at a higher rpm.
    This is due to a cam change, and that's the point of my posts here.
     
    Last edited: Dec 9, 2023
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  13. squirrel
    Joined: Sep 23, 2004
    Posts: 55,644

    squirrel
    Member

    No, the cam is the same. The peak power happens at higher RPM because the engine can breathe better because of the larger valves, manifolds, and carb.

    If you want to see the effect of just a cam change, compare the 300 HP and 340 HP engines.
     
  14. 6narow
    Joined: Jun 1, 2008
    Posts: 555

    6narow
    Member

    Allowing the engine to use less power to operate will change the amount of power you have on tap, but it won't change the rpm, because the valve events remain the same.
    The way to change rpm, is to change the cam.
    Anyway, according to that one sheet, the stock cam for a 327 is the "097" Duntov cam, and we all know that ain't right.
    Trust me, there's a cam change with the 300 as well.
     
  15. 427 sleeper
    Joined: Mar 8, 2017
    Posts: 2,811

    427 sleeper
    ALLIANCE MEMBER

    The stock cam for the 340 hp and 360 hp 327 IS the 097 Duntov cam. The short block's for a 250 hp and 300 hp are IDENTICAL, including the cam. A better breathing top end will allow for more power at a higher peak rpm. Power was restricted by the smaller top end of the 250 hp version.
     
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  16. squirrel
    Joined: Sep 23, 2004
    Posts: 55,644

    squirrel
    Member

    I don't know how to explain it any better than that ^^^^
     
  17. Fordors
    Joined: Sep 22, 2016
    Posts: 5,304

    Fordors
    Member

    I agree with @squirrel about @427 sleeper ’s post the only thing I might add is that passenger cars used the AFB or a Rochester with the PowerGlide for some reason on the 300 horse engines.

    IMG_9981.jpeg
     
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  18. finn
    Joined: Jan 25, 2006
    Posts: 1,257

    finn
    Member

    You could say that the smaller carb is comparative to putting a tighter fitting cork in the intake system. The small carb just can’t breathe as well, so power drops off at high rpm.
     
  19. If you guys can step out of your misogynistic shoes for a minute.... put Mona Lisa Vito on the stand. She'll tell you what's bullshit and what is fact! (credit to "My Cousin Vinny")
     
  20. 427 sleeper
    Joined: Mar 8, 2017
    Posts: 2,811

    427 sleeper
    ALLIANCE MEMBER

    :confused::confused::confused:
    There's absolutely no misogyny. When someone spout's B.S., they're gonna get checked... plain and simple.
     
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  21. flyin-t
    Joined: Dec 29, 2004
    Posts: 1,420

    flyin-t
    Member

    My dad and my uncle bought '64 Impala wagons at the same time. Our was just the basic Impala, but had AC! we were towing the flatbottom to the river with moms Falcon with an inline 6 and no AC before that. My uncle special ordered his wagon, Vette engine, dash mounted tach, 4 spd and posi rear end. That was my aunts daily driver for a decade, then my cousins drove it to school. What a fun car, wish I had the foresight to have bought it when they let it go for a song. I do still have the 327 out of our's sitting in the corner of the garage.
     
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  22. HEATHEN
    Joined: Nov 22, 2005
    Posts: 8,511

    HEATHEN
    Member
    from SIDNEY, NY

    '64 is when the Duntov cam was replaced by the "30-30" cam.
     
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  23. 427 sleeper
    Joined: Mar 8, 2017
    Posts: 2,811

    427 sleeper
    ALLIANCE MEMBER

    '64 is also when 2.02/1.60 valves came into production.
     
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  24. DDDenny
    Joined: Feb 6, 2015
    Posts: 18,987

    DDDenny
    Member
    from oregon


    Also..............
    GM hinted at offering the 327/365 hp (L76) engine in the (new for 1964) Chevelle, some have claimed they made a couple test mules.
    Anybody seen one?
     
  25. 427 sleeper
    Joined: Mar 8, 2017
    Posts: 2,811

    427 sleeper
    ALLIANCE MEMBER

    Never saw one but have read that it was a COPO option.
     
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  26. DDDenny
    Joined: Feb 6, 2015
    Posts: 18,987

    DDDenny
    Member
    from oregon

    As rare as rockinghorse crap!
     
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  27. I had read the same thing. Something tells me that someone had gotten a hold of one back then.;)
     
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