Distributor recurve kit advertises 20 deg advance but I only get 10 @ crank!

Discussion in 'High Performance Modifications' started by BondoSpecial, Oct 5, 2009.

  1. BondoSpecial

    BondoSpecial Veteran Member Lifetime Gold Member

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    Sep 20, 2004
    Southern Maryland
    I used an accel brand HEI recurve kit, the advance plate and weights of which are identical to the Spectre recurve kit (I had both side by side). The distributor is a brand new, not remanufactured, GM unit.

    Accel advertises that you get 20 degrees of advance AT THE CRANK using their weight and any of the springs (with varying rates of advance). I am only getting 10 degrees at the crank with accel's kit!!! I tried flipping the center plate but it was very obvious which way the plate goes, if you put it on upside down the weights don't touch it or retract.

    I tried both the 2 medium springs, and now I am running 1 medium, 1 light. The advance comes in early enough and the car runs fine with 24 initial, 34 total but I am curious why I am getting half the advance they advertise.

    Nothing is sticking and the weights move freely. I greased the pins and also in between the weights and the base of the dist, there is no drag at all.

    And before anyone says "those recurve kits are all crap, get the Crane kit", they don't sell the crane kit anymore!!!

    Thanks

    Steve
     
  2. BondoSpecial

    BondoSpecial Veteran Member Lifetime Gold Member

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    Sep 20, 2004
    Southern Maryland
    Here is how CHP shows installing the kit. This is the opposite of how the picture on the spectre package shows the center plate being oriented!! And it's not because of reverse rotation, the spectre picture has the weights going in the same direction. So either spectre or CHP is wrong.

    I installed my center plate the way spectre showed. It seemed like flipping it to chp's way did not work right w/ the weights closed but I will try again.

    [​IMG]

    I would certainly get more advance this way as the "tails" of the weights will have more room to move before hitting the stop.

    Hmmm

    If it turns out that spectre's instruction sheet is wrong, there are probably a lot of people over the years that have put these kits in wrong and never knew

    Steve
     
  3. Kamikaze

    Kamikaze Veteran Member Lifetime Gold Member

    Steve,

    I've done it the way the photo shows because I always ran the weights full in rotation to where the tangs mated up with the indentation of the center plate.
     
  4. BondoSpecial

    BondoSpecial Veteran Member Lifetime Gold Member

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    Sep 20, 2004
    Southern Maryland
    Here are pictures of my actual distributor and recurve kit with the center plate installed in both orientations.

    Orientation #1 - this is how I am running the setup on the car and only getting 10 degrees advance at the crank (5 degrees at the cam)

    [​IMG]

    Orientation #2 - this is how CHP shows it in one of their articles referenced above

    [​IMG]

    Notice that with the weights fully retracted and touching the center plate, there is a gap between the center plate and only one of the weights. Either (a) there is some design reason for one weight to lead (b) there is a machining flaw in the horribly quality weights and center plate or (c) there is a machining flaw in the $350 us-made brand new GM distributor

    I'd fathom that option a. is possible, b is probable, and c is almost impossible.
     
    Last edited: Oct 5, 2009
  5. BondoSpecial

    BondoSpecial Veteran Member Lifetime Gold Member

    8,695
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    Sep 20, 2004
    Southern Maryland
    To further confuse things, here is a picture from a random Hot Rod magazine article, where you can see they installed the center plate backwards from how CHP did it. Either CHP or Hot Rod has their distributor together wrong

    [​IMG]
     
  6. FatnLow

    FatnLow Veteran Member Lifetime Gold Member

    1,949
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    Mar 12, 2003
    Montgomery, AL US
    Just for info here is the link to Moroso curve kit. In reading it flipping the center piece is for clockwise or counterclockwise rotation of the distributor.
    http://www.moroso.com/catalog/images/72300_inst.pdf
    In the past I thought that the fat side of the weight went on the high side of the plate like the CHP picture. I have had the best luck by just using the factory plate and weights and experimenting with the springs. I'll take a picture of mine tonight if you want. I just know from experimenting aftermarket weights must use the aftermarket centerplate.
     
  7. BondoSpecial

    BondoSpecial Veteran Member Lifetime Gold Member

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    Sep 20, 2004
    Southern Maryland
    I know flipping the center plate is for reverse rotation, but even those instructions don't establish which way up is for which rotation. You can see in my pics above that when I orient my weights like the CHP picture, I have a gap where one weight does not touch the center plate. That may be its own manufacturing defect issue

    I'd take a look at a close up pic of another aftermarket weight/plate set to see if they have that odd gap on one weight like mine. Otherwise I don't need a pic of a stock weight/plate set, I have several stock HEI distributors.

    The problem with the stock weights is they give you so little initial timing -- too much mechanical advance. My engine with the f'd up aftermarket weights put together (likely) wrong by me, 24 initial 34 total actually runs well but the idle speed hangs even with stiffer springs, which I think is from having the plate in backwards and/or from the poorly stamped parts.

    Confused!
     
    Last edited: Oct 6, 2009
  8. FatnLow

    FatnLow Veteran Member Lifetime Gold Member

    1,949
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    Mar 12, 2003
    Montgomery, AL US
    I'll look over what I have. I know I have a couple of old kits. As for your hanging idle, since your initial timing is set to 24 did you have to screw your idle screw way out to lower the idle? If you do the butterflies would be pretty much closed. Is it possible the motor is trying to get air from somewhere else forcing a vacuum leak?

    Also you state 24 degrees initial and 36 total are you doing this with the vacuum advance hooked up? I do not see how else you are not getting initial plus 20 degrees mechanical advance. My setup is 16 initial and 36 all in at 2500 with VA plugged. As for your pics, I'd run the bottom pic.
     
  9. BondoSpecial

    BondoSpecial Veteran Member Lifetime Gold Member

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    Sep 20, 2004
    Southern Maryland
    no I am still within the range of adjustability of the idle screw and I am in the middle of the idle transition slots, everything with the carb is hunky dory.

    There is no vac advance involved here, I am omitting it until I have the mechanical curve set up properly.

    I only get 10 degrees advance at the crank, 5 at the dist, so there is my 24 initial 34 total (that 36 total was a typo I meant 34). It's due to my clodged up weights and/or clodged up assembly of them.

    My major beef is with how if I install that center plate properly, one weight does not touch. Although I extoll the virtues of my made in usa new gm distributor that was purchased from a dealer, maybe it really does have something wrong with it. I will set up the same weights on a crap used nasty HEI and see if there is still that gap there.
     
    Last edited: Oct 6, 2009
  10. Todd80Z28

    Todd80Z28 Moderator Staff Member Lifetime Gold Member

    11,057
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    Jun 11, 2002
    Northern VA
    What happens with orientation #2 when you put the springs on?

    I f'in hate those Accel/Mr. Gasket curve kits. I've never gotten one to work correctly and reliably. If they were the only choice left, I'd adapt a distrbutorless setup to the car- no BS.:mad: I have a box of plates and weights that I've scrounged up over the years, and I use that.
     

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