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TPI Distributor question *Update* more ?'s

Discussion in 'The Garage' started by Hossbaby50, Nov 4, 2003.

  1. Hossbaby50

    Hossbaby50 3/4 ton status

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    TPI Distributor question *Update* more ?\'s

    *Update*

    Distributor gears between an 85 HEI and 88ish TPI distributors WILL NOT work. The shaft on the TPI dist. is smaller and the gear just flops around. Thing brings up the next question.

    Can I just buy an aftermarket brass gear to fit the TPI shaft? The brass is softer then the steel in my cam correct? Thanks

    I have read conflicting things. I have read that the distributor from and 87+ TPI system can be used in my 85 motor. I have also read you can't. Then I have read that you must swap the distributor gear from an 85 distributor onto an 87+ distributor because of the difference in metals between the motors. What is true? I have both distributors and swapping gears is no big deal. Is that all I need to do? Thanks

    Harley
     
  2. HarryH3

    HarryH3 1 ton status Author

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    Re: TPI Distributor question

    The '87 'vette TPI motor came with a roller cam. Roller cams are made from a much harder steel than flat tappet cams. Roller cams require the use of a bronze distributor drive gear, to keep the harder gear on the camshaft from wearing out the distributor gear quickly. (Some aftermarket roller cams use a pressed-on "soft" drive gear, so that this isn't required). However, I've never read or heard anything about using a bronze drive gear with a flat tappet cam.

    The gear is just held on my a roll pin, so swapping it isn't difficult. /forums/images/graemlins/cool.gif
     
  3. Triaged

    Triaged 1/2 ton status

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    Re: TPI Distributor question

    didn't TPI's use mechanical advance HEI's for 85? Don't the newer small cap ones have no mechanical advance?
     
  4. HarryH3

    HarryH3 1 ton status Author

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    Re: TPI Distributor question

    I think what he's saying is that his TPI setup is from an '87. The engine he wants to install it on is an '85. /forums/images/graemlins/cool.gif
     
  5. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Re: TPI Distributor question

    I had researched this info myself when I did a TPI swap on a blazer I used to have. You can use any distributor gear since the factory cams that were roller used a soft sintered iron gear even though the cam itself is a billet. Also most after market cam companies also use a sintered iron gear on their cams for the same reason as GM. The 85-86 TPI's used a large body HEI distributor with in cap coil whereas 87-on used the small body distributor with seperate coil, they are interchangeable with the correct wiring adapter.
     
  6. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Re: TPI Distributor question

    On TPI's there is no vacuum or mechanical advance in the distributor, it is all controlled by the ECM.
     
  7. Hossbaby50

    Hossbaby50 3/4 ton status

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    Re: TPI Distributor question *Update* more ?\'s

    I tried swapping the dist gears last night. No Go.

    The shaft for the TPI is smaller (thinner) then the 85 HEI dist. but the gear itself appear to be the same size.

    Can I just buy a brass distributor gear for the TPI and use that? I imagine that the brass is softer then the steel in my cam so I shouldn't have to worry about wear correct? Thanks

    Harley
     
  8. 87GMCJimmy

    87GMCJimmy 1/2 ton status

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    Re: TPI Distributor question *Update* more ?\'s

    This is a stock 87 GMC Jimmy TBI truck distributor. Got it a autozone before I put the TPI on my truck. It just happens to be the same part # as the non roller cam TPI systems.

    Mike
     
  9. Hossbaby50

    Hossbaby50 3/4 ton status

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    Re: TPI Distributor question *Update* more ?\'s

    So it will work. Awesome. I just bought a new cap and rotor for it and am going to throw in a new pickup coil and call it good. Thanks again for the millionth time Mike.

    Harley
     

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