Register now to get rid of these ads!

GM Inline 6 Interchange Guide? 230, 235, 261, 270, 292, 302 Stovebolts?...

Discussion in 'The Hokey Ass Message Board' started by Buzznut, Nov 2, 2010.

  1. Buzznut
    Joined: May 9, 2008
    Posts: 2,312

    Buzznut
    Member

    I'm pretty good at searching the internet and all I seem to find with regard to GM IL6 engines is parts for 230, 235, 261, 292, but nothing stating that it will fit 270 and 302 blocks. Will the parts listed for the 230, 235, 261, 292 also bolt onto the 270 and 302 engines? Specifically I'm looking at the aftermarket Offy intake manifolds, distributors, water pumps, exhaust manifolds, etc... Anyone have experience with these?
     
    Last edited: Nov 2, 2010
  2. Buzznut
    Joined: May 9, 2008
    Posts: 2,312

    Buzznut
    Member

    I'm hoping to start stockpiling parts as soon as possible... Anyone?
     
  3. Snarl
    Joined: Feb 16, 2007
    Posts: 1,640

    Snarl
    Member

    Which engine are you trying to build, and why haven't you talked to the part suppliers?


    Nothing interchanges between the 194/230/250/292 Chevy and the 216/235/261 Chevy or 228/256/248/270/302 GMC.

    You can modify a 250/292 HEI dizzy to work in the GMC or the 216/235/261 Chevy, but that's about it.

    Some parts interchange between the GMC and 235/261 Chevy, but not many.
     
  4. Buzznut
    Joined: May 9, 2008
    Posts: 2,312

    Buzznut
    Member

    I'm going to be building up the 270 I have and have been looking online at Langdons and Patricks, etc... but finding nothing for the 270. I was mainly looking at the Offy 4bbl intake and some cast exhaust manifolds, and my water pump is missing. I'm also going to go .040 to .060 over and will be needing new slugs, rings, etc.. I'm going to have the head done professionally. I ordered this book and it should be here in a couple days:

    http://www.amazon.com/How-Hop-Chevrolet-GMC-Engines/dp/1931128073/ref=pd_sim_b_2
     
    Register now to get rid of these ads!

  5. Buzznut
    Joined: May 9, 2008
    Posts: 2,312

    Buzznut
    Member

    Maybe by renaming this thread we can use it as an interchange guide...
     
  6. guiseart
    Joined: Apr 7, 2005
    Posts: 3,872

    guiseart
    Member

  7. pdq67
    Joined: Feb 12, 2007
    Posts: 628

    pdq67
    Member

    I have to, I just do!!

    You want to look at something different to use, then start looking at the Gimmie V-6's!!

    Gimmie made some BIG V-6's through the years.

    Hell, maybe a double V-6, V-12 or two??

    I never knew about them until my ol' RR Buddy started talking about his ol' Gimmie P/U and just how it's V-6 pulled like a John Deere..

    Have you got a copy of Leo Santucci's great as close to a modern 6-banger book that there is??

    pdq67
     
  8. Buzznut
    Joined: May 9, 2008
    Posts: 2,312

    Buzznut
    Member

    I have Santucci's book...it's a great resource, but he doesn't cover the GMC 270's or 302's... I'd love to see an updated version with these engines included.
     
  9. squirrel
    Joined: Sep 23, 2004
    Posts: 26,520

    squirrel
    Member

    You need to get the old Bill Fisher book if you want to find something printed about GMCs.

    California Bill's Chevrolet, GMC & Buick Speed Manual, 1954 Edition
     
  10. Buzznut
    Joined: May 9, 2008
    Posts: 2,312

    Buzznut
    Member

  11. Gigantor
    Joined: Jul 12, 2006
    Posts: 3,809

    Gigantor
    Member

  12. Buzznut
    Joined: May 9, 2008
    Posts: 2,312

    Buzznut
    Member

    Can I ask anyone who might know what the specific differences are in exhaust and intake manifold design?
     
  13. RichFox
    Joined: Dec 3, 2006
    Posts: 6,664

    RichFox
    ALLIANCE MEMBER

    GMC manifolds do not interchange with 216-235-261 Chevy sixes or 195-215-230-250-292 Chevy/GMC sixes. 228-248-256 and most 270 GMCs have smaller intake ports than 302 and 270H heads. So the port alingment rings don't interchange. Did you join Inliners International? It was started to promote 270-302 GMC engines.
     
  14. 302GMC
    Joined: Dec 15, 2005
    Posts: 2,241

    302GMC
    Member
    from Idaho

    Cast headers for the 216-261 fit the GMC 228-302. Port matching should be done.
     
  15. Snarl
    Joined: Feb 16, 2007
    Posts: 1,640

    Snarl
    Member

    The GMC is the most expensive of the three engine types to build.
    Yes, you can get parts for them, but you need to inquire, not just surf the internet.
    Patrick's and Tom Langdon are your best bet for rebuild parts. Speed and dressup parts are mostly limited to vintage, but they still make the Howard 5 carb intake, and Fentons are available for it. Jim Carter Truck Parts has some parts listed for it. You could also try Larrowe & Sons truck parts...
     
  16. Kinky6
    Joined: May 11, 2003
    Posts: 1,541

    Kinky6
    ALLIANCE MEMBER

    Hmmm, now I know that the intakes for the 235/261 don't interchange with the GMC, so it would seem that the port spacing for the exhaust would be different as well. :confused: In an old Patrick's catalog I remember seeing the Fentons for the Chevies and the GMC as being listed as two different items. But I've never gone and measured the port spacing on my GMC to compare to the Chevy.


    Later, Kinky6 :cool:
     
  17. Snarl
    Joined: Feb 16, 2007
    Posts: 1,640

    Snarl
    Member

    Jim Carter lists two different Fentons...
     
  18. motion guru
    Joined: Oct 18, 2009
    Posts: 118

    motion guru
    Member
    from yacolt, wa

    I believe the castings are the same - the machining is different. The port spacing is close enough that if all you try to do is split the difference between the forward/aft single ports and the middle siamesed ports . . .

    I spent a day at Langdons(meant to say Patricks) and among other things watched shopping carts full of rough castings being machined on jigs. One shopping cart of castings rolled in - and boxes were packed with Chevy versions off of one machine and GMC versions off the other machine.

    I have been snagging GMC speed parts whenever the opportunity affords - if you keep your eyes open, stuff pops often enough to make a build up possible.

    I ran across a 40 ft container stuffed with innumerable NOS GMC parts and carted home all I had money for a few years ago. Lots of Vietnam era NOS parts for military GMC engines that fit the civilian versions just fine.

    If a 270 is what you want to build - and you don't need everything tomorrow - just be patient, watch eBay and craigslist - and be ready to buy when the parts surface.
     
    Last edited: Nov 4, 2010
  19. 23crate
    Joined: Oct 6, 2010
    Posts: 141

    23crate
    Member
    from nz

    id be quite keen on a twin carb manifold and some headers for a '61 261...
     
  20. Buzznut
    Joined: May 9, 2008
    Posts: 2,312

    Buzznut
    Member

    If they're that rare then I'm not parting with this engine any time soon... I'll build it. so far I really only need a resource for intake manifolds, water pump and fuel pump. I'm likely going to alter the HEI unit mentioned above, I'll find the Fenton exhaust and will keep the original GMC scripted valve cover. Jims Chevrolet is about 1 hour from me and I know Jim pretty well from building a few 55 thru 59 pickups. I'll pick his brain about parts..
     
  21. Alfster
    Joined: Jan 15, 2002
    Posts: 1,167

    Alfster
    Member

    We started with a 270 GMC. Made our own Intake manifold with 5 single barrel Stromberg carbs. HEI from a late Chevy six went straight in. Head has been milled nearly an 1/8 inch. Has Chev V8 valves and heavy duty valve springs. Lightened flywheel. Track cam (specs unknown) and headers.

    Runs real strong.

    Gets used and abused everywhere.
     

    Attached Files:

    Last edited: Nov 4, 2010
  22. OldBuzzard
    Joined: Mar 8, 2008
    Posts: 777

    OldBuzzard
    Member
    from MA.

    I got my fuel pump at NAPA. Bring them the number off the old one. They might even be able to get a water pump.

    Patrick's has a 5 carb intake as well as internal engine parts.
     
  23. 33-Chevy
    Joined: Nov 30, 2007
    Posts: 268

    33-Chevy
    Member

    I am probably not supposed to give a pitch for my own business, but try : www.34-chevy.com and click on available parts. We rebuild water pumps and sell new Offenhauser and new Clifford parts. We sell parts for all the engines you mention plus GMC 270-302.
     
  24. fleetside20
    Joined: Dec 19, 2012
    Posts: 1

    fleetside20
    Member

    what parts are interchangeable between the 250 and 292 chevy?
     
  25. A little friendly advice: Go do an introduction before you get roasted.

    To answer your question, the 250 / 292 are the same family. Nearly everything interchanges. The only problem you will run in to is things like power steering brackets. The 292 has a higher deck height to make more cubes, and thusly the power steering brackets are different to account for the 292s taller block. All of the intake/exhaust parts are the same. Beware of the late engines, some have integrated heads.
     
  26. Mitchell Rish
    Joined: Jun 10, 2007
    Posts: 307

    Mitchell Rish
    Member
    from Houston MS

    I believe Bruce Murry up in Wash. State is still running a 6-71 blown 302 jimmy in his anglia- Check the inliners membership roster to get a number- He helped me cure the mysterious flywheel problem that every one always has - smart guy - cured it and it didnt even hurt -
    And as stated Ebay etc has GMC stuff -pretty regular - of yea - go to the OLD GMC TRUCKS web site - nice people - lot of stuff on there.
    Mitch
     
  27. This thread is 2 years old. I think the problem is solved.:)
     
  28. paintman27
    Joined: Apr 23, 2011
    Posts: 85

    paintman27
    Member
    from new jersey

  29. paintman27
    Joined: Apr 23, 2011
    Posts: 85

    paintman27
    Member
    from new jersey

  30. gemnewt
    Joined: Jun 7, 2008
    Posts: 290

    gemnewt
    Member

    Does anyone know the lengths of the 235 & 292 inline 6, I was wondering about clearance problems in a 49-54 Chevy passenger car. Will I have to run electric fan in lieu of mechanical fan?
     

Share This Page

Register now to get rid of these ads!

Archive

Copyright © 1995-2013 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Terms of Service. Privacy Policy.

Atomic Industry
Forum software by XenForo™ ©2010-2014 XenForo Ltd.