400 SBC Points/Dwell Gap Setting

Discussion in '1955-1959' started by Stephen Shaw, Jan 10, 2022.

  1. Stephen Shaw

    Stephen Shaw Member

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    Sep 18, 2015
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    I have a 400 SBC in my '57 3200 with the type of distributor with the mech. advance just under the round screwed on rotor. What is the secret for presetting the points gap? I can't even see when the cam bump is set on the points and sure as heck can't get a feeler gauge in there to measure. Before the points where changed, the dist hold down loosed up so the timing is off too. So it's not something I can fudge the gap, get it running and then use a dwell meter. Or at least I think that's the case. Thanks in advance for any help.
     
  2. Bill Hanlon

    Bill Hanlon Member

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    A dwell meter will work, no matter what the timing is set to. Engine might (probably won't) run because of the timing, but the dwell can be set. Just so you don't have to worry about backfires and such, pull the coil wire from the middle of the distributor until you get the dwell set.

    Or you could "old school" the points and set them to 0.016" (0.019" if new). If you can't see them, take the "round screwed on rotor" off while using the feeler gauge.

    Real old school is using a match book cover instead of a feeler gauge.
     
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  3. Stephen Shaw

    Stephen Shaw Member

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    Thanks Bill. As you stated I was able to set the dwell using a dwell meter while cranking the motor with the starter. I thought it had to be running to set the dwell. There is just no possible way to get any kind of feeler gauge past the mechanical advance weights to measure the points gap.

    Just a few more questions related to this... Is there a year/make/model I can use to get parts from the local auto parts store that they will recognize? Since the '57 never was available with the 400 SBC they are at a loss when it comes to getting parts. Is there any way to reference the distributor with the round screwed on rotor they would understand? They seem to only know the other type of pop off rotor? Once I have a car/ truck to reference, I will be able to get a new rotor and cap. Thanks.
     
  4. Bill Hanlon

    Bill Hanlon Member

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    If you are looking for engine (or ignition) parts, specify the year that the 400 Chevy V8 is from. Distributor parts (points and condenser) for Chevy V8s are pretty generic starting in 1957 (the first with externally adjustable dwell) until HEI in the mid 70's.
     
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  5. lonehorn57

    lonehorn57 Member

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    Growing up around GM "point system"-type distributors, I always felt they were a pain in the rear. Once when I went to an autoparts store & asked for a "points file", they thought that I was an antique... Not having room in my engine bay for an HEI-style dist., I got an older earlier version distributor & put it in my modern 350. But, i eliminated the "points" by going to a electrical ignition Pertronix III setup. Works great.
     
  6. coilover

    coilover Member

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    Haven't used a point distributor since I moved out of the cave but when I did I set the points on the GM top weight BEFORE I put on the rotor. Now if we want to keep the original look we put the rotor/stator/pickup in the original housing and mount the module somewhere outside housing where it gets a cooling air flow. The advantage of this is the factory parts are cheap while Pertronix is not.
     

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