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Oldsmobile 455 bellhousing patttern same as Chevy?

Discussion in 'The Garage' started by Okiemuddog, Sep 27, 2003.

  1. Okiemuddog

    Okiemuddog 1/2 ton status

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    Hey guys, I have got a line on a solid complete and running '76 Olds 455, the question is........... I have heard that Olds and Pontiac used a different bolt pattern on their bellhousings than Chevy did, Is this true? I just want to know before I buy this engine and find out it won't bolt to my tranny /forums/images/graemlins/angryfire.gif. Anything else I need to look out for when swapping form a 350 to a 455? Thanks in advance



    Krennen /forums/images/graemlins/thumb.gif
     
  2. Beast388

    Beast388 1/2 ton status

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    Yep, the BOP's are different than the Chevy's.....
     
  3. jjlaughner

    jjlaughner 3/4 ton status

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    From the best of my knowledge the 350 pontiac and 350 Chevy have Different bolt patterns. Dont know for sure on the big blocks though /forums/images/graemlins/thinking.gif

    /forums/images/graemlins/rotfl.gif
     
  4. SUBFAN

    SUBFAN 1/2 ton status

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    NO, same as Buick, Olds, Pontaic though....Adapters can be purchased though.

    Olds 455 is a good grunt motor, don't rev the piss out of it without some help in the oiling department....
     
  5. SUBFAN

    SUBFAN 1/2 ton status

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    There is no such thing as a 'big block' Pontiac....
     
  6. Okiemuddog

    Okiemuddog 1/2 ton status

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    SOOOOOOOOOO, is there anyway to make one bolt to a Chevy tranny? or am I just SOL and going to have stick with a SBC?
     
  7. SUBFAN

    SUBFAN 1/2 ton status

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  8. Okiemuddog

    Okiemuddog 1/2 ton status

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    NM, found it in my Jeg's catalog /forums/images/graemlins/thumb.gif
     
  9. Seventy4Blazer

    Seventy4Blazer 3/4 ton status

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    you can have a pontiat th400 or th350 bult as a 4x4 version. or you can buy the adaptor plate from jegs/summit. or you can use a divorced T-case. i have thought about the idea big time as i have access to two free BOP motors. a 455 and a 425. i SHOULD go get both of them with the trannies. but i got to much going on right now.

    Grant
     
  10. MJB774X

    MJB774X 1/2 ton status

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    4 of the 6 bolts will line up
     
  11. diesel4me

    diesel4me 1 ton status Premium Member

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    The bolt pattern is different,but gm had turbo 350 trannies from 78-82 that had both bolt patterns because gm had a strike at some of the engine plants and they put 307 olds,301 pontiacs,and buick 350's in some of the chevys that would normally have had a 305 or 350 in them.You could also get a diesel 350 old tranny and put a torque converter from a gas motor in it (different stall speed on a diesel)it will bolt right up.Or you can use an adapter plate from TCI as the other guy said,from jegs or summit for about 55 bucks. /forums/images/graemlins/grin.gifI'd go with a turbo 400 if possible on a big block,but I've run TH350's without a problem too--but they were steet driven mostly--but my plow truck has had one 13 years with no trouble,but I dont use it for a bulldozer either! /forums/images/graemlins/rotfl.gif
     
  12. dyeager535

    dyeager535 1 ton status Premium Member

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    [ QUOTE ]
    You could also get a diesel 350 old tranny and put a torque converter from a gas motor in it (different stall speed on a diesel)it will bolt right up.

    [/ QUOTE ]

    Don't know where you got that info, but it's wrong. An olds 5.7L diesel is the same externally as a 350 gas Olds motor, and as such, has the same bellhousing bolt pattern as all other BOP motors.

    And before you get on me about that statement, I do know that the 350D and 350DX (early and late 350 diesel castings) have big block size main journals with small block rod sizes, zero CC heads, much thicker castings, a different lifter valley setup (for the diesel injection pump), roller lifters on the DX blocks, different pistons and rods, and so on.

    I doubt the dual pattern TH350 had anything to do with the availability of the transmissions...some Oldsmobiles sold in Canada came stock with Chev engines (in the 70's and 80's) and thus it probably made more sense to have one tranny that fit both applications, as well as one that could bolt up to the BOP applications in the states.

    The 200-4R is also a dual bolt pattern tranny 95% of the time, but was used behind Chev and BOP pattern engines in the US, so it makes sense to use the same housing for all divisions, which is my reasoning for the above statement.

    Of course, it makes more sense to usethe same engines and trannies across all divisions, and thats why you have GM the way it is now.
     
  13. diesel4me

    diesel4me 1 ton status Premium Member

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    A customer at the store I worked at bought a pair of 82 C20 pickups from the local phone company for 1500 bucks each in 1985,when the trucks were popping the olds diesels like popcorn--they werent gm's best diesel,thats for sure,but we got together and I found him a 455 2 barrel out of a 68 delta 88,and we converted one to the gas 455,the tranny bolted up,but we found the converter was either defective or too slow a stall speed for a gas motor,we changed the converter and it drove fine--the olds 350 diesel and gas V-8 share the same bolt pattern on the bellhousing.I dont know the exact reason for multiple bolt pattern trannies(I heard the strike theory from factory reps,probably another popular rumor)but I'm glad they did make them that way(it should be a law!)--it sure makes it easier at engine swap time.I think its cool to see a caddy,pontiac or buick motor in a gm truck,they pulled those 6000 lb barges around pretty well,I"ve oftem wondered why gm didnt do it first,after all its all in the family! /forums/images/graemlins/grin.gifIts amazing how well they fit with a minimum of hackery,and how well they perform. /forums/images/graemlins/eek.gif
     
  14. SkulzNBonz

    SkulzNBonz 1/2 ton status

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    Krennan,
    Big Daddy Raymo has a BOP pattern th400 that cam out of some Diesel truck that I'm sure he'd give you a fair deal on.

    John
     

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