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Thread: My 1979 Cutlass - 455 or 403 in place of 260

  1. #1
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    Default My 1979 Cutlass - 455 or 403 in place of 260

    Ok, so I'm debating - I have a 1979 Olds Cutlass Calais, rust free and clean, with a 260 and 47k original miles swap that solid, yet not particularly impressive, Olds V8 for another Olds V8 of more impressive displacement:

    1) Have a decent running (when pulled 8 years ago) 1972 455 I am in possession of be rebuilt, and put it in there, and deal with some of the tight clearance issues

    or

    2) Have a 403 built (the shop would find a block), and do an "effortless" swap.


    I'm not planning on going rowdy with either the 403 or 455... ideally I'd like something that peaks an unholy amount of torque at a stupidly low RPM, and peaks horsepower somewhere in the 4500-5000 RPM range (uh, if we were measuring things with the exhaust on, etc)

    Of course, I realize that clearance issues put a huge limit on intakes and headers if I go the big-block route.

    Now, I'm lazy, have limited time, and ZERO fabrication skills. I'm given to understand from what I've gotten from http://www.robertpowersmotorsports.com/G-bodyV6-V8.html is that I only have to worry about a single alternator bracket (which I foolishly did NOT keep from the donor car), and a bunch of modifications to mount the R4 type compressor.

    I absolutely, definitely want to keep my working A/C system.

    For the alternator, I just have to find something from a donor car...

    For the A/C . . eh, yeeaaahhhh, uhhh...

    Does anyone by any chance make these brackets pre-fabbed for this sort of swap?

    (I usually don't write so wandering-train-of-thought-ish, by the way, but I DO usually say a lot before I get to my actual question)
    1979 Olds Cutlass Calais
    260 V8
    Carmine Red Metallic

  2. #2
    Administrator 88hurstolds's Avatar
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    455 swap is a no brainer.
    People tend to think in terms of Chevy when they say Big Block.
    A 455 is not a big block, it's a tall deck block by 1.2" so this only affects where the valve covers wind up under the hood and does not put the intake up higher as some would think... however this is not an issue in G Bodys. There is plenty of clearance with the AC box and hood. I was able to fit a stock dual snorkel air cleaner under my hood. The issues starts to arise when you go with a taller intake but that also holds true with 403's.
    Also, you can run your stock accesories, all you need to do is put some washers between where the alternator bracket and Power Steering Bracket connect, about 1.2" of them. I used one of those spacers used for the lower PS bracket where it meets the block, heck you can use an old socket, just need a longer bolt is all.
    Check out my swap:
    http://www.gbodyolds.com/forum/showt...hp?99-455-Swap

    The second issue is headers which are not required if you are running stock or mild stock (W30 cam).
    They ran manifolds in the 70's with these so it doesn't hamper performance if you have a good system out the back.
    If you want headers, get your wallet out.

    Now the third and biggest issue is running AC.
    You will have to extend the bolt hole area, no getting around that.
    Bring the bracket to a machine shop and have them weld in tabs and follow

    To allow the AC to function without the computer read this, but this holds true for any car that you take off the computer including the 403, not 100% sure if '79 260's were computer controlled so you might be alright:
    http://www.gbodyolds.com/forum/showt...-cruise-and-AC

    and

    http://www.gbodyolds.com/forum/showt...out-a-Computer
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    Well, computer's not an issue, as the car's a 1979.....

    ... and I do know it's just a matter of different deck heights and all....

    Is it true what the link I have says about the alternator bracket? Did you use the alternator bracket from the donor car the 455 came from, or did your 307's bracket fit?

    Were I to go 455, I'd definitely use the W/Z reproduction manifolds.... how's the intake selection when using a stock hood, though? I thought there was just stock, stock Toronado 455, and, well, that's it? Not so much with the intake being taller, but if it is, having to go with a smaller or drop air cleaner assembly (both of which, if I understand it correctly, will lose a bit of the gains you'd get in breathing with the better intake? Or not?)

    If I do the 455 build . . well, if the W30 in 1972 could do 300 horsepower/400-ft-lbs (net), then I'd probably want to go somewhere in the 350 to 400 range (net) for horsepower, and maybe in the upper 400s to maybe touching 500 (again, net), for torque. So, more than what they manged in 1972, but I guess relatively tame (hopefully fairly attainable) given the displacement, by today's standards.
    1979 Olds Cutlass Calais
    260 V8
    Carmine Red Metallic

  4. #4
    Administrator 88hurstolds's Avatar
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    Yes, alt bracket from a 307 works, the 455 is a 307 basically.
    WP, distributor, any bracket that doesnt bolt to both the block and head will work.
    Its all explained in the thread including adding an RPM (or torker) intake since they are of similar height.
    Stock style 455 with C heads will get you where you want to be.
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