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

    Well, you only have 12 degrees of mechanical advance, so the weights are not moving very much. Could be that there isn't much difference in the Crane springs, in the short amount of travel. You can try some heavier springs like those in the Mr. Gasket kit. It's OK to have all your advance in at 1400, as long as you have no hot start problems, and you aren't getting a big drop in RPM, in and out of gear. You don't want the advance curve at idle speeds, but sometimes it is unavoidable.

    As far as vacuum advance is concerned, you can add 8*(limit the cannister), so you cruise at about 42*. Just adjust the spring tension(allen key) to eliminate part throttle ping
     
    Last edited: Jun 7, 2006
  2. jaystoy

    jaystoy Well-Known Member

    Would just like to say Larry is the man!!!!!!!! He exhaustively walked me through the powertiming process, and now my 71 350 runs ooh so good, thanks Larry!!
     
  3. Gran Sport66

    Gran Sport66 Well-Known Member

    does all of this apply to Nailheads in same way?

    New to this, and I think I get most of it-just have to actually get into it to see how the vac can works.

    Are dist's different, and the timing setup different for nailheads?

    I realise most of this was basically the same for years on many GM's, but nailheads aren't very high-revving.

    Starting with 4-5 initial, 20 mech, and 10 or so vacuum will be OK for just about any BB engine?

    As for the bushing for the cam, can't you use any metal tubing of approximate size, with a nut on the pin to hold it in place?

    Also, saw this on the Jegs site-a dual-points setup. What does this do for ya? Anyone recommend these?

    here's the link:

    ACCEL dual points setup

    Also on Jegs, they have ACCEL 32-OZ. and 48-OZ. points replacements. They don't specify anything other than 57-77 GM V8 for BOTH types. Which one do you want, or does the size relate to the size of your engine?

    Thanks! :laugh:
     
    Last edited: Jun 12, 2006
  4. LARRY70GS

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


    Yes, all distributors are different. They differ in the amount of mechanical advance that is built into them. One thing is the same though. Buick V8's, be it nailheads, or the 400-430-455 series of engines, like 30-34* of total advance at wide open throttle. This is how they were set up at the factory, but the stock distributors didn't allow all the advance in until high engine speeds. You can get a seat of the pants improvement in pewrformance by getting all the advance in before 2500 RPM. This applies to all V8's really, not just Buicks. When you use lighter springs to speed the mechanical advance curve, you need to shorten the amount of degrees in the vacuum advance to avoid overadvance at part throttle.

    You can use anything that will fit on the pin and stay there for a bushing. As long as it stays put, and doesn't bind, it will work.

    Dual point setups have been around for a long time. The idea is to increase coil saturation for a better spark. You are better off with an electronic conversion. Points wear from the time you put them in, and the spark deteriorates accordingly. The spring tension decreases over time, and points tend to bounce at higher RPM's. The 32 or 48 oz. probably refers to spring tension. Electronic ignition will always provide more accurate timing.
    .
     
  5. Gran Sport66

    Gran Sport66 Well-Known Member

    Ok, but for those of us who for whatever reason can't switch, is it worth it to try to do a dual points setup, go with "OEM" style $9.99 points, or go with something a bit more beefy, like the ones Jegs has from ACCEL?
    Or, would regular, OEM points not be much different?
     
  6. LARRY70GS

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



    Most people seem to complain about setting one set of points, 2 sets are double the work. I would just use stock points and change them more often. If I was firing a high RPM screamer, I'd go with heavy duty points for that reason.
     
  7. bluenellie

    bluenellie Well-Known Member

    Larry,
    Why do you think that this is such a better way to limit the vacuum advance? I did it the way Crane suggests--by using the rear most vacuum advance canister mounting screw to mount the black cam--doing it that way means no drilling and tapping a hole to mount the cam, all that has to be done is to adjust the initial timing to counterbalance the advance that takes place when the vacuum advance pin is limited in its travel...I suppose as long as either way works then it doesn't really matter...I guess I was just curious :)
     
  8. EEE

    EEE Straight out of lo-cash!

    It's been a whole year since I last looked at this and I never got to it to sort this out. Now it's time for the Ratfink day at the track again on the 8th of July and I want to have it sorted by then. The car has been running slower than ever and I never made it back in to the 17's so something has to be done.
     
  9. EEE

    EEE Straight out of lo-cash!

    YES!

    The car is a lot happier and so am I. We even took on a BMW Z8 last night and he didn't have us until he hit second and kicked it sideways and was off.

    I screwed the vacuum cansiter all the way in, then modified it so it could only pull 8-9 degrees with one of those little metal tabs and two screws.

    Then I partially blocked off the built in advance with two screws, and filed the rotor to make sure it wouldn't bind.

    Marked up the new 30 degreees mark on the damper.

    With two light black springs from mr. gasket kit #929g installed, we took the enigne up to 1300 rpm's where it stopped advancing and turned the distributor to the new 30 mark to hit the zero on the timing cover scale.

    Then changed to a set of silver springs freom the mr gasket kit that mentioned having the advance in at 2000rpm's.

    We floored it a couple of times and there was no knocking so maybe I can try for another degree or so.

    - - - - -


    The car has a lot more go in it.. I'm all psyched for the ratfink event at the lancaster track on July 8th when we can take it down the track... The car has a best of 17.21, I'd be really happy if we could see it in the 16's..


    Thanks Larry!!! and thanks to all the rest of you who posted here! If you have an HEI and haven't done this, you really should do it..
     
  10. Smartin

    Smartin antiqueautomotiveservice.com Staff Member

    Kimson, your car should be easily into the 16's if you're tuned properly.

    I hit mid 15's with only good exhaust and a quick timing adjustment by Larry in 2003.

    Funny thing is, I have only been able to shave a half second with everything else I've done.:Dou:
     
  11. Floydsbuick

    Floydsbuick Well-Known Member

    Kimson,

    Let us know how it does on the 8th! I've suspected your car needed this. :TU:
     
  12. LARRY70GS

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

    Just got back from Indy, or I would have answered this sooner. When you do it the way Crane instructs you to, it advances the timing, and at the same time, it preloads the spring inside the cannister. So everytime you move the cam one notch, it advances your base timing 2*, and you should retard the timing 2*. It does this because you are actually pushing the link further into the cannister, and moving the baseplate at the same time. Mounting the cam on the arm of the cannister allows you to adjust the amount of vacuum timing independent of spring preload, without affecting your base timing. The spring preload is adjusted with the allen key through the vacuum nipple. Whatever works for you is fine.
     
  13. stagedgs

    stagedgs 1967 GS400

    I just installed a mechanical advance curve kit in my distributor. I was kinda surprised that the brass advance limiter bushing just slid on when I installed it. I was expecting a little bit of resistance, but there was none. Maybe I just don't know my own strength.
    Should I worry about the bushing vibrating down and eventually sliding off the pin? I understand that centrifugal force will help keep it in place, but over time will the bushing vibrate down and off of the pin?
     
  14. LARRY70GS

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

    Mike, just make sure the bushing is actually bottomed out on the pin, it might not be. There should be a slight interference fit. A little epoxy inside the bushing can't hurt. Once installed, it shouldn't move.
     
  15. stagedgs

    stagedgs 1967 GS400

    That's one thing I did do correctly, is make sure the bushing was pushed all of the way onto the pin.
    Thanks.
     
  16. jtcasper

    jtcasper Well-Known Member

    Hi Larry

    So I have been reading over this thread for quite a while. I have a 67 Riviera GS with a 430. I just got the car a few months ago and to the best of my knowledge the motor is completely stock.

    When I first got the car the initial timing was set at 15 Deg. I am now down to 6 Deg with some lighter springs, I did that based on a recommendation from a friend. The problem was that at 15 Deg it would ping very easily. With it set where I am at now I don't have as much bottom end, but it still pings under a full throttle acceleration, usually right before it shifts into 3rd gear.

    If what I am reading applies to my stock motor I should be able to by the Crane Cam kit and also the Mr. Gasket kit. With those I should be able to limit the mechanical advance with the bushings so I get a total advance of 30 Deg with a higher initial timing. Also I can limit the Vaccum advance so it is only about 8 Degrees or so.

    If I do this do you think I will be able to get rid of my ping and get back some of the bottom end I lost.

    I appreciate this thread, it is very informative and has taught me a lot about timing.

    Thanks very much, Joe
     
  17. LARRY70GS

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

    Hi Joe,
    Here are the specs for the original distributor that came with the car. The top # is the distributor #(1111149) that should be in the car. You might want to check that. The second # down 2 1/2* is the initial timing at idle with the vacuum advance disconnected and plugged. The advance starts at 1000-1200 RPM. There is 17-21*@1800 RPM, and maximum advance of 28-32*@4800 RPM. Vacuum advance starts with as little as 6-8" of vacuum, and is at it's maximum of 14-18* at 16" of vacuum. So at Wide Open Throttle (WOT), at 4800 RPM you will have 30-34*(2 1/2 +28-32*) If the distributor is the stock one that came in the car, an initial timing of 15* would give you 43-47* :eek2:No wonder it pinged. Even 6* will make your total timing 34-38* That will probably be too much also. The only way to use more initial is to limit the mechanical advance. If there is no bushing on the pin in your distributor, you can use the brass one supplied in the Mr. Gasket Kit. I would certainly order the Crane Kit. Then install the 2 yellow springs. Use a 30* mark on your balancer to set your total to 32* Put your original springs back in and see where your initial timing falls. Then install the bushing along with the yellow springs and again set the total to 32* Again reinstall the original springs and see where your initial timing is. The yellow springs will be ideal for setting your total advance, but will not show your true initial because they will allow the mechanical advance to begin at idle speeds. That is why I advise you to use your original springs to check your initial. Once you are sure of how much mechanical advance you have(after the bushing install), you can be sure of what initial timing will get you what total timing. Play with your total timing and springs to get the advance in below 2500 RPM with no ping at WOT. Do all of this with the vacuum advance plugged. Once you have this optimized, then adjust the vacuum advance. You want around 40 * at cruising speeds for best gas mileage. In most cases, 6-10* is all you need. Again, you want no part throttle ping. You may need to adjust the amount of degrees in the cannister as well as the spring tension (allen wrench) Good luck. :TU:
     
    69GS430/TKX likes this.
  18. jtcasper

    jtcasper Well-Known Member

    Thanks Larry

    Thank you very much for that info. I will order those kits this weekend, probably from jegs or summit. The Napa by me didn't carry them. I will post my results when I can. Could be a couple weeks as I am very busy right now.

    Thanks again,

    Joe
     
  19. jamyers

    jamyers 2 gallons of fun

    For what it's worth, here are the size specs of the stock advance-limiting bushing in a points distributor (from NAPA's website):
    Height:.2"
    I.D.:.188"
    O.D.:.265"
     
  20. jtcasper

    jtcasper Well-Known Member

    Finally got a chance to play with the timing

    It has been a very hectic summer. I finally have had a few days in a row to drive my Buick so I have been playing with the timing a little.

    I installed the two yellow springs and I had 43 deg of total timing. I have since installed the brass bushing and right now I am sitting at 32 deg of total with 8 initial. All that is with the vacuum plugged. With the vacuum hooked up I have 20 deg at idle. I am using the two blue springs that allow the total all in at I believe it is 3200. The car is running pretty good. I don't seem to be having any ping at WOT, until it shifts into 3rd gear. When it hits 3rd and the RPM's come down it ping's very bad. It will do that with the vacuum plugged or hooked up.

    Also right now, only once in a while mainly when it is cold outside if I am cruising along and stab the throttle it falls flat on its face. I think that might be another problem. They just switched us over to our winter time fuel here which has about 10% ethanol in it.

    If the weather holds I will try and drive the car for a couple more days this week.

    Overall I am pretty happy with the results so far. I would like to get the advance to come in a little sooner, but I need to get rid of the ping in 3rd gear.

    Joe
     

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