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Technical Olds flywheel onto a Cad...

Discussion in 'The Hokey Ass Message Board' started by warbird1, May 9, 2015.

  1. I've acquired a '36-48 Olds 8 cyl. stick flywheel that I'm thinking about installing on the back of my '55 331 in order to couple it up to the old Ford tranny in my '40. Questions are what do I do with the pin on the back of the crank flange on the Cad? Are there any balance issues I need to be aware of? And I am aware of the tooth count issue on the ring gear/starter and have that handled. Thanks!
  2. F&J
    Joined: Apr 5, 2007
    Posts: 13,223


    I do some Olds Rocket V8 stick stuff. I picked up what was said to be, a Olds 6 flywheel that was "a thing that was used on Olds/Cad V8 swaps back then".

    Mine may or may not be a 6. Mine was redrilled for the Olds V8 pressure plate, for use with Olds V8 and early Cad 331 motors. The stock holes were equally spaced, not three pairs of holes like the Olds V8 plate has. Is yours like that?

    This flywheel is thinner/lighter than Olds/Cad V8 wheels.

    One more question; the early Olds and early Cad 331 had a non symetrical 6 bolt crank pattern, that only fits in one postion. The flywheel I am talking about, also has that pattern, and there is no dowel pin on the Olds crank. So, is you later Cad crank have a symetrical pattern? is that why it has a dowel?

    One thing that is a problem with my version, is that the clutch mating/wear surface is closer to the crankshaft. That means the Pressure plate, and therefore the TOB, will be farther forward,... and on a flathead trans, the TOB might try to extend beyond the guide tube, or almost off, causing it to get crooked/stuck.

    There was a short thread on these flywheels a few years ago, and someone mentioned a spacer between the wheel and crank. I am almost sure these flywheels were called "6 cylinder Olds". I am not sure what you have
  3. I identified mine by checking the timing mark, a steel ball embeded in the front of the flywheel, against the listings in a old Motors Manual, so I'm fairly certain of what it is out of. Supposedly the 6's had IGN or TDC marked on the flywheel while the 8's had a small steel ball for the timing mark. It has the three pairs of holes drilled and tapped for the stock pressure plate and has also been re-drilled for the stock Ford 9" pressure plate and another one I haven't identified yet.
    This flywheel has the Olds non symmetrical bolt pattern with one hole being elongated to fit a symmetrical bolt pattern. The Olds motors never used a dowel pin to locate the crank while the Cads did so the front of the flywheel hasn't been drilled for the pin. Just trying to figure out what they did about the pin "in the old days".
    And yes, the face of the flywheel has a recess for the disc and pressure plate to fit into. I am aware that this may mess with the throw-out bearing geometry, but figured I'd measure everything, mock it up and see how it looks.
  4. F&J
    Joined: Apr 5, 2007
    Posts: 13,223


    Sorry I could not help, other than bumping this thread back up, in the chance someone might recall these inline flywheel swaps.

    I never found any old race guy that recalled these. I wondered why they went to the trouble of redrilling, rather than buying a stock V8 flywheel, or why not an aftermarket aluminum wheel. Was it a cheap way to get a slightly lighter flywheel, or maybe done before V8 wheels showed up in wrecking yards, or before aluminum ones were made.

    I'm not up on the later Cad 331 that never had a stick trans. Was it 54 or 55, I forget. I don't know what flywheels were used on the old aftermarket adapter bellhousings that were made for those non-extended blocks.

    So, I ask why are you using this wheel, vs buying either a stock earlier Cad wheel, or a repro aluminum from Ross? Just experimenting?

    I thought the only thing my 6-cyl wheel might be goods for, is a T-5 swap, as they have a longer TOB guide tube and longer input shaft. But that would be trying to add two lower trans bolt holes to the 51-64 Olds stick bell, and then the rear bell mounts can't be used, because two welded, threaded bungs need to be installed in the bell.

  5. '53 was the last year for a manual transmission in a Cadillac, though the extended block continued for another year with '55 being the first year for the flat-back block.
    I'm using this flywheel because it came with the adapter that I picked up for a good price (free). And it's the first Olds/Cad flywheel that I've come across... If necessary I'll go with a new one, but I'd like to try to make this one work.
  6. BTTT for the weekday crowd... surely someone has done this before?
  7. 73RR
    Joined: Jan 29, 2007
    Posts: 6,552


    I'd say that this is your best approach. If the crank has a positioning pin then make a hole for it or remove the pin.
    The single biggest issue with swapping flywheels is to insure that the wheel is properly registered to the crank flange for concentricity. Balance should be an easy fix.

    warbird1 likes this.
  8. Finally have the tranny mocked-up on the engine; Speed Gems flywheel, 11"" Ford clutch and a couple of adapters... DSC00318 (2).JPG
  9. I have successfully used a '40's Olds 6-cylinder flywheel on Olds Rocket and early Cad v-8's. I do not know if the 6-cylinder flywheels are the same as the inline 8-cylinders.
    warbird1 likes this.

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