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GMC inline 6 where to start for killer motor

Discussion in 'The Hokey Ass Message Board' started by speedway, Apr 27, 2007.

  1. speedway
    Joined:
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    Location:
    wichita ks

    speedway Member

    What motor to I want for starting base to build a hot 6 banger. Do I want a 302 cu. in. GMC. If so how do I I.D. that motor. Any website to check out for more info. Found what the owner claimed was a 51 GMC a few blocks from my shop for 50$. Not sure of the cu.in. Have a 57 chevy car complete motor and powerglide w a "848" head, would that be a good starting point?. If i remember correctly all the hot 6 cyl. drag cars in the 60's were GMC powered. Thanks
  2. HEATHEN
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    HEATHEN Member

    GMC made it easy; the engine size was stamped into the flat machined pad next to the distributor hole. 302s didn't debut until '52.
  3. fast_46
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    Saskatchewan

    fast_46 Member

    stovebolt.com and inliners.org are good places for info
  4. reddog14
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    100 mi west of San Antonio

    reddog14 Member

    I put a GMC 228 cu motor out of a 32 truck into a 52 Chevy truck last year, Had to move the radiator forward and build a new front motor mount because the GMC motor is about 1 1-2 or 2 inches longer than the Chevy motor. Other than that, the rest bolted right up. If I could have located a good 270 or 302 I would have kept the truck with a 6 cylinder in it. Instead, I put a 502 in it.
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  5. povertyflats
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    povertyflats Member

    I can hook you up with a 270 but sold my 302's. They are hard to find. I have a good 228 also. But maybe your neighbor's engine will work out for you.
  6. OldSub
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    Seattle, WA

    OldSub Member Emeritus

    270s seem more common than 302s, but I saw three 302s in a guy's shop today. They can be found. Look for an old GMC truck, including the WWII military types. They are out there.
  7. 3Mike6
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    3Mike6 Member

    302 was a v6, not inline...whactha trying to do?
  8. AHotRod
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    AHotRod Member

  9. 3Mike6
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    Oakdale, California 95361

    3Mike6 Member

    Ya...did ya read the title?
  10. OldSub
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    OldSub Member Emeritus

    Right.

    GMC's 302 was an inline.

    Ford and Chevy have both made V-8 302s.

    Chevy made a V-8 305.

    And GMC once made a V-6 305, which is probably the motor you are confusing with this discussion.
  11. 3Mike6
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    3Mike6 Member

    Damn, you're probably correct...that 305 was the "offset" engine...oh well, color me "off topic" then;)
  12. Kinky6
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    Kinky6
    ALLIANCE MEMBER

    The 302 was a 4" bore x 4" stroke inline six, same basic block as the 228, 248, and 270". I've also seen one each of a 236 and 256, but those are not common. About 1/2 of all the 302's from '52 to '59 were in military vehicles, like the duece and a half 6x6 trucks. Commercial versions were in 2.5 and 3 ton rated trucks.

    The 270, and when it was introduced, the 302, were the hot upgrade motor for Chevy sixes in the ten or twelve years right after WWII. They were often raced, as a heavy overbore on a 270 would yeild 292", and the 302 could bore to 320" without stroking it. At the time, you would really have to pour some work and machining tricks into a 255" Merc flattie to get that kind of displacement. They were sometimes used in customs, such as the Larry Earnst Chevy.

    With the addition of a Wayne 12 port head, the larger GMC's were capable of producing one HP per cube in the early '50's, and could hold their own against the famed Offy's in circle track racing, where they were known as the "Farmer's Offy".

    The later series of slow revving V-6's used in trucks started with a 305", and went up from there. I don't recall ever hearing about these being raced.

    Later, :cool:
  13. peanut
    Joined:
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    knoxville TN.

    peanut Member

    what was the bore and stroke of the 270? and what is the 235? b.s.? too
  14. 3Mike6
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    3Mike6 Member

    Were there Wayne 12 ports avialble for the inline 6's? I thought they were a rare commodity for the Ford FHV8?
  15. Wayne 12 ports were for chevy and gms inline sixes.How would "12 PORTS"work on 8 cylinders???Think about it,intake +exhaust= 2 valvesx8 cyl=16 ports
  16. 3Mike6
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    3Mike6 Member

    Well, I saw this '32 Arun eninge Ford, some rare thing on Ebay...touting the engine and a ""12 port wayne" setup., as I was directed to the auction, prior comments led me to believe it was smoe super rae FH V8 thing...

    I saw the two sets of "3" exhaust manifold ---caue I'm sure you now the center ports on the FH Fords V8 are common_ and assumed it had to do with that.

    But, WTF do I know, just asked a question and give you my limited knowledge as a response.
  17. 3Mike6
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    3Mike6 Member

    Sorry, it was listed as an "Ardun '33 Roadster"., I'll see if i can find the closed auction so you kow what I'm talknig about.
  18. 3Mike6
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    3Mike6 Member

  19. 3Mike6
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    3Mike6 Member

  20. 3Mike6
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    3Mike6 Member

    Lol...and clicking on the links truely shows the "12 port" engine to be an inline six.

    Damn, I just love talking to myself.
  21. RichFox
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    RichFox
    ALLIANCE MEMBER

    I ran both a 270 and a 302 motor in the same car at different times. Both have a 4 inch stroke. The 270 was bored .156 oversize to make it 292 cid. The 302 was bored .125 to make it a 320 inch motor. They both ran good and both still hold SCTA-BNI records, 27 years later.
  22. Hip
    Joined:
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    Crap-ifornia City "SUCKS"!!!

    Hip Member

    I had a 270 GMC in my '59 P/U and that thing hauled ass!!! I'm trying now to get a guy to let go of his 302 inline cause he'll never do a thing with it, but he's so far not budging!
  23. Kinky6
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    Kinky6
    ALLIANCE MEMBER


    Yeah, I had started a thread on this car the other week, sank like a stone.

    As you read the description, that '33 Ford came with a flathead V8 when new; then in the late '40's a Chevy six was installed, either a 216 or maybe an early 235 Hi-Torque, and was used as a test vehicle for the development of the 12 port head. The Ardun heads on the flathead that is in the car now were an overhead valve conversion for the flathead, where the stock Chevy and GMC engines were already an OHV design. The 12 port head just improved on this by way of better airflow in and out.

    :cool:
  24. 1952henry
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    North Dakota

    1952henry Member

    It won't help you now, but there was a fellow at the Portland Swap Meet who had 2-3 302s and at 2-3 270s for sale. Some complete and some short blocks. Shows they are out there. :p
  25. Dan Warner
    Joined:
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    Location:
    so cal

    Dan Warner Member

    I spoke with Pat Ganahl yesterday and he mentioned that he has a complete Wayne Chevy for sale. A real killer deal, new J&E pistons, Spaudling cam all the correct stuff. This would be a good period engine for a tradtional rod.

    DW
  26. Stovebolt
    Joined:
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    Location:
    Victoria Australia

    Stovebolt Member

    Why is it that whenever I hear of a 12 port for sale I'm 1/10 up to it!!!

    I've been offered 2 Wayne 12 ports for Chevs - last one was $4500, I had $450, I've been offered a 12 port for a jimmy for $2500, I had $275, and the saga goes on.

    I'd kill for that Wayne Chevy ...... any volunteers?? ;)

    Dan, how was the PRC RR? Any pics for us foreigners?
  27. That is one very historic 33 Ford,wish i had the cash.Hpoe it goes to a "worthy"owner so it stay's that way.:cool:
  28. wethebmx
    Joined:
    May 30, 2006
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    Location:
    Glendora, Cali

    wethebmx Member

    im gonna be building my 270 out of my 59 gmc truck to put in a period hot rod. the thing to do back in the day was to get a 302 block with a 270 head. or a 270 and just put a 302 crank on it. im gonna save my lunch money and buy a wayne 12 port(they still make them) and go to town. inlines are my favorite and I really hope a bunch of stupid wannabees dont read this and want to run sixes, because i really enjoy not seeing them all the time. im sure some others reading this will agree with me. o yah, and that 33 ford you guys were talking about is so awsome, i love that harry warner drove it from when it was new until the day he died and never ran anything other then sixes in it. now some goon put a flatty in it. what a shame. im kinda bummed after seeing that...damnit.

    sorry for the venting, some things just aint right.

    harry is turning in his grave as we speak.
  29. Dan Warner
    Joined:
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    Location:
    so cal

    Dan Warner Member

    Stovebolt,

    Should be another thread but, the run was really super. I counted 91 traditional roadsters, that's all that is allowed to run, there were maybe some more. The run was approx. four hours, 130 miles, through the mountains and back to the starting point. They said only one break down occured.

    No pictures from me, I'm not that good and can't work the scanner deal. Maybe someone else.

    DW
  30. Snarl
    Joined:
    Feb 16, 2007
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    Location:
    Madison, WI

    Snarl Member

    Some things of note,
    If you try to use any factory head on a 302 other than a 302 head, you will need custom pistons because of the chamber shape.

    Also, the company in Cali that was supposed to be making the 12 port heads is out of business. I believe the website may still be up, but they aren't taking any orders. Sorry...

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