Power Timing your Buick V8

Discussion in 'Buick FAQ' started by LARRY70GS, Jan 2, 2005.

  1. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    Retarded timing heats an engine up, not advanced timing. Light load cruise timing should be in the low to mid 40's for timing. All in by 3500 is fine. Supplement the rest with vacuum advance. Limit the vacuum advance to 12* and you will be at 45* while cruising. If the engine still heats up on the highway, you probably have a radiator problem.
     
    2nd Gen Buick Fan likes this.
  2. 2nd Gen Buick Fan

    2nd Gen Buick Fan Well-Known Member

    Thanks for the input, Larry. I think I'm good with the mechanical and initial timing now, but the vacuum advance canister is kicking my butt. I bought an Accel 31034 adjustable canister in 2019 and limited the pull on the unit with a small plate (like the pictures at the beginning of this FAQ thread). It's good at limiting the vacuum advance to 12*, but my engine "rattles" whenever the vacuum advance canister is connected to either manifold or ported vacuum on the Q-Jet and I attempt to accelerate with anything more than a gentle pedal. I'm pretty sure this is knocking. The engine runs like a beast without the vacuum advance and sounds great, but at 9-10 MPG. On this Accel 31034, there is no "fully counterclockwise" position that I can determine (per their instructions). The hex wrench spins infinitely in either direction. When the vacuum advance is connected, the car gets 12-13 MPG and runs 5 degrees cooler (but sounds like crap). Time for another vacuum advance canister and I'll run it without for now.
     

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  3. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    It rattles because the vacuum advance doesn't go away fast enough. I thought the amount of advance was adjusted through the vacuum nipple on the Accel unit. What you need to adjust is the spring tension so that the vacuum advance drops off instantly with moderate throttle. More spring tension raises the vacuum level necessary to overcome the spring tension, so advance is only there at high vacuum levels ( low load), but goes away quicker under high load. It can be a balancing act between amount of advance and spring tension. I like to use a plate on a stock canister because spring tension on them is pretty high.
     
    2nd Gen Buick Fan likes this.
  4. 2nd Gen Buick Fan

    2nd Gen Buick Fan Well-Known Member

    I purchased another Accel 31034 adjustable vacuum advance canister and determined that you have to push the hex key in very hard to engage the spring so it will turn (like fingers bleeding). The sweet spot for my car seems to be 7* initial, 20* mechanical and 10-12* on ported vacuum. I could get away with more initial timing until the engine was fully warmed up, but then the engine knock started. Car runs great now! I really appreciate this forum. If anyone wants a list of which McMaster Carr or Grainger springs work well for Delco distributors. I have some part numbers matched to the RPMs where the mechanical timing was all in.
     
    69GS430/TKX likes this.
  5. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    That's great, but realize at wide open throttle, you will only have 27* of timing. That is likely leaving power on the table.

    The engine knock starts with only 7* of initial timing? That is strange.
     
    69GS430/TKX likes this.

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