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Distributor Advance curve

Discussion in '1936-Present Suburban' started by Ddragggon, Feb 19, 2002.

  1. Ddragggon

    Ddragggon 1/2 ton status

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    ok, so I finaly think I've tracked down the problem with my K20... its not the timing chain ( I don't believe it is anymore) the advance weights in my distributor had well over 180,000 miles on them, and 25 odd years... somewhere in there, the bushings not only losened, but flat out wore completely out on it. so, today, I bought a 3 dollar recurve kit, and replaced the weights, bushings, and put 1 of the 3 sets of springs on it.

    my question is, whats the stock curve rate, and does anyone know the ins and outs of recurving teh advance on a distributor? right now, I still get a little backfiring at speeds over 65 ( before, it was speeds over 40) would putting say higher advance springs on it fix this problem? or will it just make me need to run really expensive fuel, and still not be any better... I'm going to whip out the timing liight, the vacuum gauges, and a better carbureator then that carter POS, and go to town on this thing, retiming, and whatnot.

    at any rate, any help on the matter would be greatly appreciated, and at worst, I'll jsut stumble through it, and figgure it out. thankyou in advance,

    -Rich

    My truck isn't ugly, you have a skewed sense of beauty

    <font color=blue>Its a Wheelbase Thing... You Wouldn't Understand</font color=blue>
    <font color=red>CK5 SUB-culture</font color=red>
     
  2. Sparky87k5

    Sparky87k5 1/2 ton status

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    You would do well to use the middle set of the springs that came with your re-curve kit. Lightest tension will cause advance to come in too early at low RPM's and "rattle" the piston tops. Heavy springs will cause a very slow advance (Almost like stock) and feel a little sluggish. Middle ones worked good for me on my last 2 small blocks. Go for about 32-34 degrees total advance (vacuum plugged off) at about 3000 RPM. Idle should be about 8-10 but key is to not go past 34-36 ever, at least with 87-89 octane.

    87 K5, 427/340hp BBC,4.56 D60 & 14BFF, NV4500, NP208, TSM rear disc's,
     
  3. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    Stock weights are a much better deal. I had the Mr. Gasket and Accel kits and they both caused me problems /forums/images/icons/mad.gif I had the thing running 16 degrees initial and still sound slow when your restarted it when hot. It would have that little too slow knock.

    A few days ago, my digital advance/tachometer snap-on timing light came from an e-bay bid. This thing is sweet, costs over $400 new, I got it for a little over $100. I had the light springs in there with the aftermarket weights. I pulled the throttle a little and things would move. I pulled real hard and it took it to around 3,500-4,000 RPM to get it to advance fully. It was only adding about 16 degrees. I found the old stock weights (which were in excellent shape) and put them back in. 60 weights and a 435? center plate (just get whatever come with the 60 weights. I got everything in and tried to start it. I had a hell of a time trying to get it to go. I checked the timing and the initial was now 4-6 retarded?! The wierd warm start was because of those rotten weights. I gave it a try with the medium springs and it was all in just a little over 2 grand. I ended up using one heavy spring from the kit and one super heavy stock weight (really fat looking). The advance started just off idle and smoothly continued until 3,000 rpm. Just like a good performance curve should be.
     
  4. MudbogAD

    MudbogAD 1/2 ton status

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    I bought the accel one. I used the lightest spring and it's just fine right now. I may go to the middles just to see how runs.
     
  5. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    I may have had too light of springs in there causing advance at idle. I don't know though because it took a noticible shot of throttle to get the timing to advance. I went back to the stock weights because they're supposed to be hardened and I knew for sure that they would give 20 degrees of advance.
     

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