anybody know about 1970 gto's?

Discussion in 'The BS Topic' started by Jimmac, Mar 18, 2018.

  1. Jimmac

    Jimmac Veteran Member

    242
    29
    Dec 24, 2013
    tucson az
    I don't want to join a Pontiac forum for 1 question so I thought I'd ask here and over on team chevelle.
    I picked up a spare frame for my 70 chevelle for cheap. it's from a 70 gto, the guy told me the car was originally a 455 4 speed 12 bolt car. According to the internet, 68-72 A body frames interchange EXCEPT the 455 gto frame.
    Anyone know why the 455 frame is the oddball frame? I saw the phscollectors
    webpage that says the same thing. BUT, there is no explanation what the difference is..thanks.
    maybe someone here might be on a Pontiac forum and can ask for me? thanks. jim
     
  2. 351maverick

    351maverick Veteran Member

    3,331
    251
    Aug 11, 2010
    erie, PA
    http://phscollectorcarworld.blogspot.com/2015/08/1970-1972-gm-body-frame-swapping-guide.html

    scroll down halfway:

    **Hey! What about those big block engines?**
    Here's the deal with those SS454, Stage 1 455s, Olds 455 and GTO 455 engines. The frames are basically altered in a couple of small but critical ways. As long as you're aware of the changes you can use a small block frame and make the changes yourself. First, with the Pontiac and Buick 455s, the engine used their own special frame mounts and were located in different spots on the engine saddle area. You'll need to get 455 frame to engine mounts and install them in the proper places.Using the 350 or 400 engine mounts in the case of the Pontiac, will place the engine in the wrong location. A picture below is given of a birds eye view of a GTO 455 engine saddle area including proper location.

    The GTO, Olds and Buick saddle area usually has a 350 engine location but the 455 engine frame has its own
    part number, is reinforced additionally front and back and has different frame mounts for the big bore V8. This
    1970 GTO shows what the 455 mounts look like and where they go.

     
  3. 351maverick

    351maverick Veteran Member

    3,331
    251
    Aug 11, 2010
    erie, PA
    that Google search took about 10 seconds ;)
     
  4. ol' grouch

    ol' grouch Veteran Member

    1,781
    416
    Jul 4, 2013
    Evansville, In.
    If I can find my old interchange books, I'll look it up. I don't trust the internet as a sole source. It's useful but wide spread knowledge isn't always right. According to the internet, red heads don't turn grey. It that's the case, what happened to me?
     
  5. The Champ

    The Champ Veteran Member

    3,753
    272
    Sep 14, 2000
    MN
    There is no such thing as a "Big Block Pontiac". The author of mav's link doesn't know what he's talking about.

    From the the 1955 287 cu in engine to the introduction of the 455 in 1970 - all Pontiacs used the same block. The difference was the journal size (listed in the order that they were introduced) - the 287, 317, 347, 370, 389, 326, 400, 350 and 303 were all small journal engines. The 421, 428 and 455 were large journal engines. A bit of trivia - the 1961-63 4 cylinder base engine in the Tempest was a 45-degree inclined 194.4 cu in (3,186 cc) created from the right bank of the 389...

    I'm not saying that there couldn't be a difference between the frames for a 455 and a 400 GTO. But if there is, it was only done to handle the increased torque potential, not because of different motor mount locations.

    When i pulled the 389 out of my GTO to put in the 455, I didn't have to change motor mounts or relocate them - as it's a direct bolt in.
     
    budro6968 likes this.
  6. budro6968

    budro6968 Veteran Member

    2,494
    344
    Apr 2, 2016
    Jax Florida
    This is true. A little research will find this info. That was always a big discussion about that.
     
  7. bfmgoalie

    bfmgoalie Veteran Member

    Had a 1970 GTO. It had a 455, 428, 400 and a 350 in it.......had a problem. The gas pedal stuck all the time. :)
     
  8. CorkyE

    CorkyE Veteran Member Lifetime Gold Member

    9,537
    265
    Nov 4, 2004
    Ringgold, GA
    Amazing that Pontiac used the same block for that wide range of engine sizes, but they did.
     
  9. Jimmac

    Jimmac Veteran Member

    242
    29
    Dec 24, 2013
    tucson az
    I talked to Philip (moderator on team chevelle and I think on here or used to be) he had a gm interchange boom and the 455 gto frame has it's own part number. jim
     
  10. Jimmac

    Jimmac Veteran Member

    242
    29
    Dec 24, 2013
    tucson az
    and I just don't see what additional brace they are talking about in that pic. looks like the frame under my chevelle. I've tried Google for pics and it always goes back tongue phs pic that maverick posted.
     

Share This Page