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Technical Pontiac 326 into a 1955 Pontiac

Discussion in 'The Hokey Ass Message Board' started by Babyblue57, Sep 23, 2015.

  1. Babyblue57
    Joined: Mar 23, 2008
    Posts: 18

    from Argentina

    Hi guys. I have the chance of buying a running 67 326.
    Im wondering how hard is to make it fit into my 1955 Pontiac.
    Engine comes with original Powerglide.

  2. DualQuad55
    Joined: Mar 5, 2005
    Posts: 1,377

    from Epsom, NH

    If I recall correctly, the 55 used a front motor mount below the timing cover and side trans mounts off the bellhousing.
    The 326 would have side motor mounts and a tail mount on the trans.
    I think these would be the biggest obstacles to overcome, not too bad. You could either make a front mount for the 326, or better yet make frame mounts and use the 326 side mounts.
    I can't recall what the X member of your frame looks like, but you may need some modification to use a tail mounted trans mount.
    For the effort, I would put a BOP pattern th350 or th400 rather than the powerglide though. Although the powerglide will function well enough, the lower first gear in the other trans will make the engine feel like it has an additional 40hp.
    No matter if you run the powerglide or a th350-th400 you will need to get the driveshaft modified, likely shortened a few inches and the correct trans yoke put on the driveshaft then make sure to have it rebalanced.
    I am not 100% sure, but I think the stock 267 exh manifolds may bolt up to the 326, however they may be slightly restrictive due to smaller ports. You might be able to do a little port matching to make it a closer match though.
    If your stock radiator is in good condition, it should do fine with the 326 so long as the engine runs well and is tuned properly.
    I think it would be a worthy swap, you get a bit more power, a little more availability for parts and best of all it stays Pontiac and the engines look very much the same.
  3. NashRodMan
    Joined: Jul 8, 2004
    Posts: 1,700


  4. 55chieftain
    Joined: May 29, 2007
    Posts: 2,188


    You'll be hard pressed to find any powerglide parts to fit your transmission, it's a st-300 2 spd used in BOP vehicles. Pontiac only used a dual bolt pattern Powerglides in about 72-73 in some of the Venturas. Use it if it's good, but most switch out to a th350 at least or th400 for the better 1st gear.

    Side mounts will need to be built or find some old style hurst engine mounts 2nd version for side mounts like what I use. I have a bunch of pics in my build thread.

  5. '51 Norm
    Joined: Dec 6, 2010
    Posts: 744

    '51 Norm
    from colorado

    Make sure that you get the starter from the '67 326 since the starters mount differently after about '63.
  6. 56sedandelivery
    Joined: Nov 21, 2006
    Posts: 6,695

    Member Emeritus

    A friends of mines son put a Pontiac 301/TH350 into a 56 Pontiac 2 door Hardtop. I guess the engine trans was free. Was't even the turbocharged version, but he said it still drove fine and had plenty of power. He built his own mounts, and did his own exhaust; it's what he does for a living. After all the work, he sold the car; it's also what he does, flips cars. I am Butch/56sedandelivery.
  7. Starter mounting is different. Up to 63 or 64 (?) Pontiac starters bolted to the bellhousing. After that they changed to bolting to the engine block (like a Chevy). I think the block casting on the later engines is a little different to accommodate the starter mounting, and I'm not 100% sure if the earlier trans/starter setup maters directly to the later style block...I think it does.
  8. d2_willys
    Joined: Sep 8, 2007
    Posts: 4,175

    from Kansas

    Your transmission is not a Powerglide, it is what Pontiac called Tempestorque. The main box is a ST-300 (Buick) or newer Jetaway (Olds), but without a switch pitch converter. As for the 326, I am not so sure that they still made the 326 that year. I would think they might have gone to the 350 Pontiac.
  9. 326 thru 1967, 350 is 1968 & up.
  10. dimitri89
    Joined: Jul 20, 2014
    Posts: 33


    Sorry to forum jack. Do you still have the origional 55 engine?

    I took my 1955 star chief v8 287 engine down to a machine shop the other day to get checked out. The engine is perfect..aside from a huge crack in one of the heads. The crack is to large to repair says the shop.

    Not sure where the heck im going to find that...does anyone know where I might find one or have any ideas?

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