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Hot Rods Let's talk Cadillac 331's, 365 and 390's

Discussion in 'The Hokey Ass Message Board' started by Roothawg, Apr 7, 2016.

  1. c322348
    Joined: Nov 28, 2007
    Posts: 343

    c322348
    Member

  2. Thanks for the info... I've in fact followed where I can so far in your footsteps. I gave got hold of a pair of 390 heads and early 390 crank. I'm planning on Chevy rods and Pistons from Diamond Racing. I'm running roller rockers but still need to source a roller cam.
    Referring back to my earlier question, reading the Allard post again they say that the Caddy suffers from harmonic problems and that at higher Rpm's the rocker stands can fracture? Unless I'm missing something surely this can be ironed out if the rotating assembly is balanced as a whole? I guess the difference here is that they're running up and down the revs in a race and pushing these motors harder than many of us are likely to.


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  3. c322348
    Joined: Nov 28, 2007
    Posts: 343

    c322348
    Member

    There may be an RPM range where the valvetrain experiences severe harmonic vibration. The cam companies have equipment to test that but I'm sure it would be expensive for a one-off build. The mass and stiffness of the valvetrain components as well as the springs would all be variables. As far as I know the balance of the crank, rods and pistons don't have an effect. You could make the rocker stands out of billet steel I suppose, and maybe they would never break. Might just be cheaper to buy another engine though!

    Roller cams are very expensive because I think they are made from steel rather than cast iron. Not sure that blanks are available for the old Caddies so it might need to be a one-off part. I wanted a roller cam but I didn't want to wait another few months to get the engine done. Also, I had enough going on without adding a valvetrain experiment to the project.
     
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  4. TERPU
    Joined: Jan 2, 2004
    Posts: 2,372

    TERPU
    Member

    Cadillac's like volume, and the stock pumps put out a ton. If there's one aspect I learned through messing with these wonderful engines is the guys that designed them had it right from the start. Stick to the stock parts as much as you can and it'll never leave you with a frown on the side of the road.

    I have to remind myself constantly that this was GM's pride and joy. Built to pull huge sleds with torque at a lower rpm. The first one I built like a SBC to rev high. What a mistake that was. understanding the "intent" of these will save you heartache down the road, and once you understand them RPM's are no longer that big of a deal. The torque way overcomes any misgivings of needing lots of RPM.

    - Tim
     
  5. This is interesting and you clearly have time served with these motors! What you say makes total sense in regards understanding the intent of the original designers.
    Knowing the similarities between this engine design and the small block chevy I had planned as you did to build it referencing some small block hop up modifications, so I'm curious as to what didn't work with this approach if you don't mind explaining further.
    Thanks


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  6. seabeecmc
    Joined: Jan 28, 2005
    Posts: 1,185

    seabeecmc
    ALLIANCE MEMBER

    Thought this might help someone. Long ago I looked on the HAMB for information on what water pump pulley to use on my '57 Cadillac engine. Found nothing. So I'll share what I found. genpull.jpg ECG-H is what I used. With this number easy to find. Ron
     
  7. TERPU
    Joined: Jan 2, 2004
    Posts: 2,372

    TERPU
    Member

    What I experienced was a few bent pushrods, side of the road time, and an engine which was way more fun at lower RPM's due to the torque it produced than the fearful sounds at 6k plus. While it would rev into the 6's easily the power came far below that, Mine pulls hard from 1000 to 4000+/- with the dual quads and a Mag. After the third time I had to tear into it I quit expecting it to rev like my 327 and learned to use it where it wanted to be. I consider the learning curve all on my mindset, not the engine. I can still shred an input on a Muncie, Saginaw, etc at ease with the torque, but breaking things is no fun.

    Reading the Cadillac specs and design philosophy was also a great eye opener. I like to learn stuff so that really made me understand and work within the expectations instead of putting my silly anticipations on it. Through all this though I have yet to break a Crankshaft, bend a valve, throw a rod, or lose oil pressure. If you rev something hard enough to bend a pushrod lots of other things are on the ragged edge. But so far the Cadillacs impress me beyond belief. I'm sure I could push it hard enough to cause catastrophic failure but that would be really dumb and cost too many fun tickets.

    I don't know if this is what you were asking for? I love all the big GM engines. Cadillac is by far my favorite.

    - Tim
     
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  8. Tim, yes very useful, thank you. I've bent pushrods in my old 283 before and spent ages chasing down problems with mismatched components. I'm keen not to revisit similar mistakes with my Caddy build so I think I'll do as you say and read more on these engines first before I go further.
    Thanks again,
    Jim.


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  9. Just been reading the last couple of pages again and will say thanks for education on these motors. Great thread.
     
  10. I've just been told that a '62 caddy oil pump, part no 1471485 is a straight swap for the earlier oil pumps and is an all round better unit with capability of flowing a lot more oil....I was wondering if anyone here had any knowledge of this swap?
    Thanks Jim.


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  11. Roothawg
    Joined: Mar 14, 2001
    Posts: 24,523

    Roothawg
    Member

    Man, I don’t know. All I ever see are overhaul kits with new gears.
     
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  12. I'll keep looking into it and if I find out more I'll post it up here. The info came from Sydney Allard's grandson. I've just bought a nice pair of old chromed rocker covers from him. I'll try and find out anything I can when I speak to him next. He has some early offenhauser rocker covers and a Weiand WCA408 manifold that he's been looking to sell also.


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  13. seabeecmc
    Joined: Jan 28, 2005
    Posts: 1,185

    seabeecmc
    ALLIANCE MEMBER

    I sent my oil pump to EGGE and they rebuilt it without the vacuum pump.
    I'd also like to know if the later, non vacuum, oil pump will interchange.
    I asked long ago while building the '57 Cadillac engine for my roadster. No one seemed to know or wouldn't share the information. Ron
     
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  14. The non vac pump will fit, basically the the only difference is the vac unit is an add on with a small hex drive that drives it. One pump has the vac pump mounted on its base, remove that and replace with a flat plate from a non vac unit.
    You will also need to blank off your vac line out the side of your block that is used to drive your wipers that have the vac pump,I believe.
     
    Last edited: Jun 21, 2020
  15. Roothawg
    Joined: Mar 14, 2001
    Posts: 24,523

    Roothawg
    Member

    I have searched google for that number. No luck. I'll keep digging. I did find this on ebay. I wonder if that is the stamping number rather than a part number?

    NOS Original GM Oil Pump Housing Gr 1.653 Gm#3632572 Casting Stamp 1471485
     
  16. Well that looks to me to be a likely candidate...most likely he got the serial number and casting number mixed up.


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  17. Roothawg
    Joined: Mar 14, 2001
    Posts: 24,523

    Roothawg
    Member

    That is the only reference I have found anywhere.
     
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  18. Dick Stevens
    Joined: Aug 7, 2012
    Posts: 3,710

    Dick Stevens
    Member

    That looks like an easy mistake to be made and looks most likely to be what was done!
     
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  19. Roothawg
    Joined: Mar 14, 2001
    Posts: 24,523

    Roothawg
    Member

    Oh and if you stumble upon the casting on 2040 parts, I have heard it's a scam out of Germany, so buyer beware.
     
  20. Hello.
    Anyone know the current rate of a engine rebuild?
    390 caddy?
    Let's say in so cal?
    Thanks
     
  21. 31hotrodguy
    Joined: Oct 29, 2013
    Posts: 2,698

    31hotrodguy
    Member

    $$$$$$$$$$$$$$$$$$$$$$$$$$
    Lol


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  22. i hear ya...more than 3k?
     
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  23. Machining should be not much different to a standard V8, depends what parts it needs,that’s where the money is.
    How long is a peice of string?
     
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  24. Roothawg
    Joined: Mar 14, 2001
    Posts: 24,523

    Roothawg
    Member

    The stock rebuild kit, which has cast pistons, gaskets etc is gonna run $1700, add 2 grand for machining and labor. I would ball park $3500-3700. That’s a very crude guess. I have no idea what machinists charge out there.
     
  25. Thank you!
     
  26. It gets expensive when you want to add performance then really expensive when you want to dress then up! Well worth it for the outcome.IMHO
     
  27. Anybody piece together linkage for 56 dual quads?
    Repro, Chevy, Mopar, aftermarket?
    A pic would help immensely.
    Thanks in advance!
    Bill
     
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  28. Roothawg
    Joined: Mar 14, 2001
    Posts: 24,523

    Roothawg
    Member

    Not yet, but I will be building one for the wcfb footprint carbs. Internet pics below.
    [​IMG]
     
    Last edited: Jul 2, 2020
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  29. Great pic! Thanks! I'm inexperienced with these.
    Had not found that one.
    Guessing that any type of adjustable threaded rod could be made to work, as they're not progressive?
    Any advice on high mount chokes? Mine are missing.
     
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  30. 31hotrodguy
    Joined: Oct 29, 2013
    Posts: 2,698

    31hotrodguy
    Member

    I would think the Chevy dual quad linkage work be easily adapted but I’d be interested to hear what people have done


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