Msd distributor without vacuum advance.

Discussion in 'Sparky's corner' started by BK455, Nov 13, 2018.

  1. BK455

    BK455 Platinum Level Contributor

    I ordered this distributor and thought it had a vacuum advance. I have a big build with 1000 cfm holley. But the car will be mostly street driven. Part number is 8517. There is no ported vacuum at carburetor. So even if i had a vac distributor i would have to run manifold vacuum. Can i achieve what i need by swapping out the springs? Still in the box, should i send it back?
     
  2. squire001

    squire001 squire001

    Ive installed two of these on my Buicks with no issues.
    One was an all stock motor and one was slightly modified......(intake and RV spec cam.)
    Crisp response off idle.
    Both have performed perfectly on the street and at wide open throttle once in a while.

    One has been on since 2001! The key is follow the charts for your type of driving when
    selecting your springs. Use the MSD springs only.
    Im about to install another one on a Jeep aplication.
     
  3. BK455

    BK455 Platinum Level Contributor

    Thanks, i was just worried about it running a little rich at idle. I asso am installing 6al digital controller
     
  4. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    If the car is street driven, I would want vacuum advance. I would return the distributor and get one of the ready to run distributors. They have vacuum advance and you can run them stand alone or with a box. Good back up for the box if nothing else. You may be able to add ported vacuum to the 1000, ask the builder.

    https://www.holley.com/products/ignition/distributors/buick/parts/8552
     
  5. BK455

    BK455 Platinum Level Contributor

    What are the negatives with my setup. A good reason why vacuum advance is better
     
  6. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    It enables the engine to run cooler and more efficiently both at idle, part throttle, and light load cruising. A race car doesn't need it because it spends most of it's time at WOT where vacuum advance won't function. With a street car, you want it. Better to have it and not need it, then to need it and not have it.:)

    I use it on my build in my signature. I also run 2 carburetors, the QJ, and my AED 1000 DP.
     
    Last edited: Nov 13, 2018
  7. buick64203

    buick64203 Right wing conservative Staff Member

    If your doing a lot of extended highway driving, you might gain some extra mpg. If your running a big cam and a Holley 1000, chances are your not too concerned about mpg or highway driving

    That's what I say about my 45 auto:D
     
  8. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    I agree:D But you can't carry it around and you know it, so it's likely that if you needed it, you wouldn't have it anyway. Hoping you or I never find ourselves in that situation.:rolleyes:
     
  9. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    There are still benefits if you are going to be mostly street driving the car. The engine will run cooler.
     
  10. buick64203

    buick64203 Right wing conservative Staff Member

    Not sure how much vacuum the OP's car is going to make. Might be a non issue. My 71 makes 7 inches of vacuum. A vacuum advance isn't going to do much good
     
    BK455 likes this.
  11. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    We don't have enough information from the OP, I agree. You can still take advantage of vacuum advance. Your making 7" at idle. Ever check it at 2000 RPM? You'll have plenty to run a vacuum advance as long as you aren't stomping the go pedal.
     
  12. Bens99gtp

    Bens99gtp Well-Known Member

    depending what box you have you might be able to lock the advance out completely, run it like 32ish then use the 20* crank retard build into the box if it is a 6520 msd box
     
  13. buick64203

    buick64203 Right wing conservative Staff Member

    Or just get the separate retard box if its not.

    7 degrees is about max out of that car.
     
    BK455 likes this.
  14. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    You mean 7":)

    I think Ben is suggesting you lock out your timing so that it makes more vacuum at idle. You can do that. Then add 8* of vacuum advance so when you are on the highway, it's about 40*:)
     
  15. buick64203

    buick64203 Right wing conservative Staff Member

    Typo...Im multitasking:D

    We tried locking the timing out. No difference.
     

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