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So...Pontiac 389...School me.

Discussion in 'The Hokey Ass Message Board' started by Paul Y, Sep 10, 2011.

  1. Paul Y
    Joined: Dec 29, 2006
    Posts: 633

    Paul Y


    I am quite versed in the Belly Button motor and its larger brother but have had nothing to do with other members of the GM stable, namely the Tin Indian range of performance engines.

    I am starting on a new project and, whilst I could have put a SBC in it some thieving toe rag decided that the 283 that I had saved would serve the world better as a baked bean can.....

    So, I have come across a Pontiac 389 for a reasonable sum but am unsure as to where to go/what to do to spice it up a little.

    From decoding the engine numbers it would appear to be a 300hp 62' motor, my question is, as I am going to be building it what would be the recommendation in terms of cam, manifold and carb and even heads?

    This is destined for a PU so not the heaviest thing out there, my preference is always for a manual box so again pointers for what to avoid etc.

    Or should I just not bother and find another 350 and dress it up to look like the 283 that is now part of a 1000 China Motor Companies finest products....

  2. I'd keep it mainly stock.. Keep the stock heads, have them cleaned up and have screw in rocker studs installed. Hammer a pair of 1-1/4" freeze plugs into the exhaust crossovers or even better, have them filled in with lead..

    I'd keep the stock intake and Carter carb (it's better then the Edelbrock).. I'd remove the choke hardware and hot idle compensator from the carb.. You could grind the manifold crossover off too.. I'd separate the water crossover from the intake for better port alignemnt..

    For cams, I get the Crower 60918 or the Nunzi 2041... From what my engine builder says, I'd stay away from the Comp XE series cam.
  3. Why do you want to block the exhaust cross over?
  4. carbking
    Joined: Dec 20, 2008
    Posts: 2,980


    If the 389 is going where a 283 was planned, and this is basically a street vehicle, just leave it stock!

    The 389 is going to furnish stock a tremendous amount of torque when compared to even a very heavily modified 283. After all you have more than 100 more cubic inches.

    The stock carburetor is a great carburetor. No need to downgrade the engine by adding a newer A/M carburetor. And it works well with a stock intake manifold.

    The original heads will work very well on the street, no need to change them, same with the camshaft. Valve job if needed, but keep the heads.

    And for the record, the two worst mistakes I have made in working on cars since 1959:

    (1) Thinking I could get horsepower out of a Pontiac 301
    (2) Blocking the crossover on my very high performance Pontiac 350

    If you do block the crossover, plan on drinking approximately 3 cups of tea each morning between starting the engine and leaving the driveway. Yes, it is good for approximately 1 and 1/2 percent increase in HP (your 300 HP engine would gain less than 5 HP); but it turns a normally very streetable engine into a very cold natured beast! Mine will idle very nicely after approximately 30 minutes!

    And great choice on the Pontiac; I think you will like it!

  5. Paul Y
    Joined: Dec 29, 2006
    Posts: 633

    Paul Y

    Thanks for the information.

    As I am renowned for having a rather heavy right foot and it looks like to is going to need a rebuild I will throw a cam in it and get it balanced.

    Did notice that stroker kits are available to take the block upto a 447....mmmmm...big block...

    Am I right in thinking that I can use a scatter shield and bolt up any 4 or 5 speed to the back of the Tin Indian or do I need a BOP pattern bell housing?

    And final question...Tri Power???

  6. carbking
    Joined: Dec 20, 2008
    Posts: 2,980


    Paul, if you are going to modify this engine; there are a couple of books which should provide you with a good understanding of Pontiac engines. These are:

    (1) Pontiac V-8's by Jim Hand
    (2) Pontiac Musclecar Performance 1955-1979 by Pete McCarthy

    Both were printed in paperback, are inexpensive, and offer valuable information about modifying Pontiac engines. :)

    As far as tripower is concerned, it looks great, but will not produce the power of either a good 4-barrel or better yet, a set of dual 4-barrels. And tripower is EXPENSIVE. And should the previous sentence not deter you, let me know. I will certainly be happy to help reduce the US balance of payments deficit. ;):D

  7. BE AWARE:

    1961-1963 blocks require an adapter to bolt to anything but a 61-64 Pontiac bellhousing or transmission (slim-jim or dual-coupling hydro). 1964 doesn't because the ear for the block mount starter was added. Without this, there is no place to hang a starter when using a newer transmission.

    I don't know if you can scare up a scattershield that will work - the same problem presents, where do you bolt the starter?
  8. Paul Y
    Joined: Dec 29, 2006
    Posts: 633

    Paul Y

    And this is why I love the HAMB...

    So, as I don't have the engine in my possession as yet is it possible to be 100% certain of the YOM by the engine number?

    The number stamped on the block is 27P which 'I think' means it is a 62 but there are various opinions from numerous sites to indicate anything from 58-64.

    So, as there is no transmission, and the intention is to fit a manual of some description, have you any pictures or more details on what the post 64 block looks like so i dont end up making an expensive mistake?

    Jon, As much as I would love to do my bit to help the US deficit I think it will have to be confined to buying the books you mentioned from American Amazon....

    Dual quads is a good option then on the 389? What size would you recommend? 400-500cfm?

  9. flamedabone
    Joined: Aug 3, 2001
    Posts: 4,899


    Try to score some pics with some good shots of the front of the intake manifold area. Numbers can sometimes be confusing, but pics will tell you if your engine is a '55-'60 a '61-'64 or a '65 and up.

    Pontiacs are very similar looking, but the three year breaks are very importiant...some stuff interchanges but not much.

    No matter what your Pontiac engine is, when you are done with it, you will throw rocks at that 283 Chevvie, I promise.

    Good luck, -Abone.
  10. propwash
    Joined: Jul 25, 2005
    Posts: 3,858

    from Las Vegas

    I had a stock 389 in a 56 B/A hdtp long ago. All the torque one could wish for and the trans was a 3spd O/ almost 23mpg on a trip to Spokane one day (taking my mom up to see her sister, so it was all under 75mph. Do the swap, it's an awesome street machine. Oops...I mean hot rod (we weren't nearly so anal 'back in the day').

  11. 55chieftain
    Joined: May 29, 2007
    Posts: 2,186


    You can buy a starter mounting plate from Butler performance or have your own made with this blueprint. This applies to 61-63 blocks. I agree with carbking a stock 389 will be more than enough power especially for a truck.

    Attached Files:

  12. carbking
    Joined: Dec 20, 2008
    Posts: 2,980


    Since Paul is a Brit, perhaps this is going in a mid-50's British lorry, and there is a place for a hand-crank!:p;):D

    Paul, some form of aftermarket dual quad manifold, and a pair of the same tag number original Pontiac single 4 carbs from any of the Pontiac 389's 1960~1965, whatever is easiest available to you. Just make sure you start with two identical units. Some modification is inevitable for best performance, but starting with the original Pontiac units means the least amount of modifications. Let me know if/when you locate something, and I will be happy to discuss the necessary modifications (on the above). As Abone mentioned, VERY important to determine EXACTLY what you have before you start buying accessories. The book I mentioned by Pete McCarthy has casting numbers by year.

  13. Intake manifold bolt pattern is 61-64 only, as well.

    64-up blocks have an ear on the left rear, 64 can have no holes, have holes but not be tapped, or be tapped for a starter. 27P does sound like an early 60s era code. Before mid-59 there is no stamped code, 1960 are two characters, and post 1964 most are two characters.

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