Stock 430 ignition advance (HEI)

Discussion in 'Street/strip 400/430/455' started by Roosevelt, Aug 11, 2015.

  1. Roosevelt

    Roosevelt Member

    Hi, I got a 67 Riviera with a stock 430. I has about 180.000 miles on it and it runs really quiet and nice.

    I have 10 degrees advanced timing at idle, I have a total timing of 32 degrees and a adjustable vacuum unit. The car has an aftermarked HEI-distributor (dragonfire). The car runs really nice, quiet and great, but my idle is not the best. However when you look at the engine it really looks free of vibrations, both in Park and drive at idle. The carb has been rebuilt and i got about 20 hg vacuum at idle (650 rpm). But, the exhaust smell and sound is not very nice at idle. Is it possible that 10 degrees advance at idle can be to much for a stock 430? I got to have 10 degrees to get 32 degrees total advance, but if the idle could be better with less idle advance, I will do that.

    Any opinions?

    Regards, from Norway.
     
  2. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    http://www.v8buick.com/showthread.php?63475-Power-Timing-your-Buick-V8

    No, 10* is fine. The fact that you have 20" of vacuum means it is idling well. What carburetor do you have?
     
  3. Roosevelt

    Roosevelt Member


    Hi, thanks for the answer. My carb is a stock Rochester Quadrajet. But the air injector-system and heat-riser system is blocked off.

    I have changed the exhaust to stock, bought from Waldrons exhaust. The car have dual exhaust, 4 mufflers, 2 on each side. I was wondering if that have someting to do with the , in my opionion, bad exhaust sound. The sound is more like puff-puff-puff...

    My spark plugs look nice after driving for a while, but idling for some time will get them a tad sooty. I also think that 20 HG is nice at idle, and when looking at the engine it looks and sounds nice. But why did Buick recommend only 2.5 degrees of idle advance and ported vacuum for the (which I use) vacuum advance? In the shop manual it looks like the total timing for these engines is 28-32 degrees.

    I have read you excellent "Power timing.." tread. :)
     
  4. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Buick engines make best power at wide open throttle with total advance of 30-34*. The original distributor had between 28 and 32* of mechanical advance. Add the 2.5* of initial advance to that and you have between 30 and 34*. The reason you see the range of 28-32* for the factory distributor is that manufacturing tolerances of the day were not so precise. That distributor could have 28*, 29*, 30*, 31*, or 32*, it will fall somewhere in that range. All that is irrelevant because you have an aftermarket distributor installed, and that distributor has about 22* of mechanical advance in it, if your claim of 10* initial and 32* total is accurate.

    I would run manifold vacuum to the distributor vacuum advance. That will speed up the idle so you can close the throttle idle speed screw a bit to bring the idle back down. That alone may clean up the rich idle, try it.

    You have 2 mufflers, and 2 resonators. If you want the exhaust to be less quiet, you can remove the resonators for a more musclecar exhaust sound. Hold onto the resonators in case you don't like the sound.
     
  5. Roosevelt

    Roosevelt Member

    I know that the original distributor had about 29-30 degrees advance in it when I checked it with a dialback timing light. The new HEI has 22 degrees advance in it when checking with the same dialback timing light, but if I try to advance it more (with vacuum disconected) to about 12 degrees, the idle is not as nice and the engine vibrates more at idle, so i figured out that 10 degrees was the best for idle quality. But if I connect the vacuum to manifold vacuum instead of ported I will get the same vibrations at idle, too much advance at idle. But as you say, the idle speeds up with more advance, but I really want a smooth idle.

    mufflers/resonnators, I had only two muflers before, nice sound, but a little noisy at 50-55 mph. Now the car is very quiet at speeds, and i like that, but the sound and smell at idle is not good enough.
     
  6. Roosevelt

    Roosevelt Member

    GM HEI in a 67 430 and recurving with MSD kit?

    Hello, I'm just wondering if my "Dragonfire" HEI could be recurved with the use of MSD advance kit 8464 ? I need the HEI to be more like the original distributor with a lot of advance built in the distributor. This is no racing machine, I just don't want to advance the initial timing more than 5 degrees because of the idle quality and exhaust smell.

    So will the MSD 8464 fit my HEI distributor? Or do I have to change the weights too? Like the MSD 8428?

    8464 http://www.summitracing.com/int/parts/msd-8464/overview/

    8428 http://www.summitracing.com/int/parts/msd-8428/overview/

    8628 http://www.summitracing.com/int/parts/msd-8628


    Thanks for answering. I'm living in Norway, and I don't want to order more than I need.

    Regards.
     
  7. Houmark

    Houmark Well-Known Member

    Re: GM HEI in a 67 430 and recurving with MSD kit?

    Don't you have any US vendors in Norway?

    Alternatively, you can order your recurve kit from Denmark.. I bought mine from HenrikUSA.dk for 189DKK which is ~20% more in NKK.. That's probably cheaper than shipping from US..

    My kit came from Mr. Gasket and was good quality..

    Houmark, Denmark
     
  8. Roosevelt

    Roosevelt Member

    Re: GM HEI in a 67 430 and recurving with MSD kit?

    There are a lot of US vendors in Norway. Only problem is that I really need so much advance that is in the MSD kit. It doesn't look like there are any other kit's with 29 degrees advance?
     
  9. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Re: GM HEI in a 67 430 and recurving with MSD kit?

    First, what you want to do is the opposite of what most are trying to achieve. Most people with modified engines want less mechanical advance so that they can run more initial advance which a bigger cam will like. A lot of GM HEIs already have larger amounts of mechanical advance so most of the kits look to reduce that with different weights and center plates.

    The MSD 8464 kit is for MSD pro billet and other distributors made by MSD that use advance stop bushings. The GM HEI does not.

    I do not know what carburetor you are using, but if it is a Quadrajet, it is easy to have the throttle blades open too much so that the carburetor runs on the main nozzles instead of the idle system. This causes very rich mixtures at idle, a rougher idle, and tip in hesitation. More initial timing helps here so that you can close the throttle more and get the carburetor back on the idle system.
     
  10. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Re: GM HEI in a 67 430 and recurving with MSD kit?

    OK, so it looks like you started a new thread for the same reason as this prior thread,

    http://www.v8buick.com/showthread.php?300293-Stock-430-ignition-advance-(HEI)&highlight=

    I think your problem may be the Quadrajet carburetor you have. It may not be the proper carburetor, Quadrajets were all individually calibrated for the engine they were intended for. What is the carburetor part number?
     
  11. Roosevelt

    Roosevelt Member

    Re: GM HEI in a 67 430 and recurving with MSD kit?



    Thanks for answer.

    I know that, but this is a stock 430, all original from 1966 (it's a 67 registered in oct. 66). No modifications. The idle is fine now with 5 degrees initial timing, the problem is that the distributor (HEI) I do have now only has 16 degrees advance in it, so my total timing is only 21 degrees. So the engine is fine with idleing, cruising and get good mileage, but with full trottle the advance is to small and on higher revs it has a lot less power now than with the original distributor (with pertronix). If I advance the timing at idle more, and leaning the idle on the carb the exhaust smell is not vey good. Over 10-12 degrees initial timing and the engine has no longer a good idle performance in my opinion. I have about 19 hg with vacuum at idle, at 650 rpms. The driveability is great now, but the power on higher revs is on the low side.
     
  12. Roosevelt

    Roosevelt Member

    Re: GM HEI in a 67 430 and recurving with MSD kit?

    I don't have the car here now, but it's the original Quadrajet from 1966 (67), but it's rebuilt a couple of times. I have owned the car for 14 years now, and have never had a problem with it actually. Not any major problem now either, but the new HEI distributor has to little advance built into it, I think.
     
  13. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Re: GM HEI in a 67 430 and recurving with MSD kit?

    I would look at replacing the weights and center plate, or possibly modifying what you have now. See if you can get more weight travel. See if you can find some HEI distributors you can use parts from. It doesn't have to be a Buick distributor, the weights and center plate will interchange among GM distributors.
     
  14. Roosevelt

    Roosevelt Member

    Re: GM HEI in a 67 430 and recurving with MSD kit?

    Thank you Larry. I will try that. I love the Riviera, and the engine is just soo smooth and powerfull, even when it's all original.
     
  15. Roosevelt

    Roosevelt Member

    I'll like to update this thread, when i finally today got my Buick running ok, and it turns out that my old timing light was not accurate.

    My HEI-distributor got 20 degrees of advance in it, but quite late, so I changed the springs so it is all in around 2500 rpm. With 12 degrees at idle and 20 degrees advance my totalt timing is 32 degrees. I had to lean out the idle mixture on the Quadrajet a litte, and 3/4 turn out it idling at 700 rpms and have about 20 hg vacuum. Now the Buick actually runs quite good. At cruising the vacuum advance get the timing (looks like) around 50 degrees. I can not hear any spark knock, but 50 degrees sounds like a lot? I runs very easy now I think.

    Thanks to all replies on this thread.

    One last question: How big can the spark plug gap be now? I think my gap is a bit big with it's .060 gap.? The ignition don't miss or anything, but the big gap puts more load on the coil?
     
  16. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    50* is a lot, but if you go too far, the engine will surge at cruise. If you don't feel it surging and you have no part throttle ping, you can go with it.

    In order to gap a plug that big, the plug has to be designed for it with a longer ground electrode. Like an R45TSX. If you open the gap too much the ground electrode ends up not perpendicular to the center electrode. Personally, I see no reason to go any bigger than .045.
     
  17. Roosevelt

    Roosevelt Member

    ____________________________________________________________
    It cruises very easy at all spees up to 55 mph, that's the speed limit where I live. It looks like around 50 degrees but it's kind of hard to see, I just have a ordinary timing light, so I marked 30 degrees on the vibration damper, and that mark get's a bit longer than the 16 degrees mark at the timing cover.

    The spark plugs is the NGK 6945, 0.060 opening, bought to a 75 Riviera with the 455. I also ha Denso 5026 with 0.044 gap. You think that's better? The original was 0.030 or 0.035 gap. With the original distributor and the pertronix ignitor kit (old one) I used 0.035.
     

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