Got it running

Discussion in 'Race 400/430/455' started by BuickGSrules, Apr 23, 2021.

  1. 69GS430/TKX

    69GS430/TKX Silver Level contributor

    That is a great question. Back in the 80s I would use the highest-octane leaded gas I could find, and THEN add octane boost (and lead substitute after leaded gas became scarce). It helped tame the pinging when accelerating somewhat, but not the after-running problem. You could switch the key off, put the trans in first, and drop the clutch, and if you didn't have your foot hard on the brakes, it would squeal the tires and leave a skid mark before the engine stopped. I wanted to try Av Gas--115 or higher if possible--but I never got hold of some from the local airport. I think I have found a local supplier of Sunoco racing fuel, which will be great if it's true, but right now, while I am setting the timing and carburetor and adjusting things, I am using 93 octane unleaded (of course) with Lucas octane boost and Red Line lead substitute, for the valve seats.

    This engine runs great when you advance ignition timing a lot. The downside of that is the pinging under load, and the after-run, and the hard re-starts on a hot engine.
  2. 69GS430/TKX

    69GS430/TKX Silver Level contributor

    Thanks, Adam. This cam needs at least 1100-1200 RPM to idle. And it's not a smooth idle, if you've heard an engine that has a Window Rattler. Kenne-Bell said don't even think of using this cam in a car with an automatic trans.

    But you are right--when I had the carb idle screws set so lean that the engine wasn't getting enough gas, idle would get so low that it died down pretty quickly when it stalled. So maybe I can rig the throttle linkage so there is a "kill switch" notch below the regular idle setting. I could trip that when it's time to shut down the engine.
  3. standup 69

    standup 69 standup69

    How much initial timing is in it ? The more the better with the big cam ...less timing down low puts more heat in the exhaust valve and cause a hot spot
    Max Damage likes this.
  4. 69GS430/TKX

    69GS430/TKX Silver Level contributor

    I degreed the cam when I installed it but that was 35 years ago so I don't remember what the settings ended up being. Back then, all I cared about was maximum torque so I chose this cam. But the power band starts at 3300. If I could do it over, I would get a less power-making cam with lower lift and less duration, so that the torque range would start at 1000 or 1500 RPM.

    As for ignition timing, it has 15 degrees initial and 30 degrees all in by 2500-3000 RPM. I have never used vacuum advance on this engine, the previous owners had already set it up without it and it ran good that way, so when I did the rebuild I did the same. But I did recently add an adjustable vacuum advance, so I could see if it would make any difference, maybe help drivability in daily driving. I haven't played with it yet, though.

    As for heat, YES this thing makes tons of heat. Overheating had always been a problem until I upgraded the radiator and added additives to the coolant. Electric fan is coming soon.

    I used to always park on a slope so when the hot engine wouldn't re-start I could coast downhill and pop the clutch to start it. The new hi-torque starter now seems to be handling hot restarts okay.
  5. Philip66

    Philip66 Well-Known Member

    I have a 13:1 engine in my 70 and although it gets pricey and tends to limit the driving, I wouldn't think about even starting it without Sunoco Supreme. It's 112 octane and leaded. In my humble opinion that high of a compression has to have an equally high octane. Mine starts easily and shuts off just as easily.
    If you buy the 5 gallon cans of 112 it's over $15/gallon, but if you buy a 54 gallon drum it drops down to $9/gallon and some change, and it's pretty easy to get a drum delivered to you. Sorry to keep your thread sidetracked, Jan.
    Best of luck with the 494!
    Max Damage and 69GS430/TKX like this.
  6. 69GS430/TKX

    69GS430/TKX Silver Level contributor

    Thanks, Philip, I do plan to run the Sunoco, perhaps mixed with pump premium if I can get away with it.

    And my apologies to Jan as well for steering off his topic! :)
  7. BuickGSrules

    BuickGSrules Gold Level Contributor

    No problem Guys, I am glad we can find a solution to your problem.
    69GS430/TKX likes this.
  8. telriv

    telriv Founders Club Member

    All you basically need to do is use an idle solenoid like on A/C cars that kicks the idle up when you turn on the A/C but your now using it to lower the idle speed to where the throttle will back off enough to help it not to keep running. All you would have to do is supply 12 vlts. when the key is on. Turn the key off now the solenoid releases the throttle to a much lower speed & the engine should turn off every time. Would depend of course how low the idle screw setting will go.
    Doing all this "afterun" stuff is definetly not doing any of the engines internals much of any good.
    Just my humble opinion.

    Tom T.
    GS464, sean Buick 76 and 69GS430/TKX like this.
  9. 69GS430/TKX

    69GS430/TKX Silver Level contributor

    Hey, great idea Tom! I may even have one of those solenoids lying around. Will just need to figure out how to attach it. And I agree, dieseling is not good for the engine, unless the engine is a diesel. :)
  10. sean Buick 76

    sean Buick 76 Buick Nut Staff Member

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  11. telriv

    telriv Founders Club Member


    IF it's a Q-Jet Ames makes a soleniod holder/bracket. They don't have new solenoids any lomger.

    Tom T.
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  12. 69GS430/TKX

    69GS430/TKX Silver Level contributor

    Thanks, Tom! Good info for future use. I know it's considered blasphemy by many Buick owners, but I am running a Holley on my engine. It had a 650 DP on it when I bought it, and I liked its responsiveness but it didn't dump quite enough fuel. Next I tried a Q-jet and a Thermoquad, but I guess I wasn't good enough at getting them to work well with my engine, so I have come full circle and now have a 4150 (850) and plan to use it for the time being. But I did have an idea that is similar to the idle solenoid solution: I could install a manual choke and just choke the thing when it's time to shut it down. :)
  13. telriv

    telriv Founders Club Member


    To me that would be like adding fuel to the fire. It's running on probably from a hot spot & adding fuel would more than likely make it worse in my opinion.
    69GS430/TKX likes this.
  14. 69GS430/TKX

    69GS430/TKX Silver Level contributor

    Hmm, I hadn't thought about that. Thanks!
  15. Bens99gtp

    Bens99gtp Well-Known Member

    Just for your info. It sounds to me like you could really use more initial timing. I know this weird, but I have get proper on my motor and when I went away from a swinging dist to a lock out unit with a crank exhaust temps dropped about 500*F at idle......

    By chance do u have an msd ignition, it is possible to get feedback from the alternator that cause ignition run on issues too.

    But it only takes 1 burr on head, 1 carbon deposit to cause an issue like this especially of high compression engine that have a high idle.

    On a side note I was able to lower my idle about 400 rpms after the locked out timing. My motor is only 12:1. But in the winter I often run it on pump fuel since I'm not flogging on has no issue shutting right off.

    Tell us more about your there a reason your wanting to stay with that much compression? It isnt the best way, but a headgasket swap and new pushrods can make a big change in compression. For not much investment
    Last edited: May 13, 2021
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  16. Bens99gtp

    Bens99gtp Well-Known Member

    Jan can't wait to get an update on how she runs for u
    69GS430/TKX likes this.
  17. BuickGSrules

    BuickGSrules Gold Level Contributor

    Me neither - just sitting here waiting for the borders to open.
    69GS430/TKX likes this.
  18. 69GS430/TKX

    69GS430/TKX Silver Level contributor

    Thanks for the suggestions. As for initial timing, I have experimented over the years with different amounts of it and it seems to start and run best where it's set now. When accelerating, it's always been prone to pinging, which I've tried to address via octane booster without much success. I plan to try Sunoco 110 and see how it likes it.

    Exhaust temps are probably high judging by how hot the engine compartment gets. I've never measured them but I now have a no-contact thermometer so I will check the temps next time I run the engine. What should the temp be?

    I am using the stock '69 distributor with Accel Points Eliminator, with no vacuum advance. If I could retard timing when shutting down the engine, I think it would stop the after-run.

    I didn't choose to have compression this high--a previous owner did some major machining on the block and heads, probably as a cheap way to get horsepower (he had access to a speed shop after hours, so the labor was free). He used the car for street racing. I doubt he ever took it to the track. When I bought it I was young (18) and all I cared about was going fast, so I didn't try too hard to make the car more streetable. I rebuilt the engine with Kenne Bell parts to replace weaknesses the former owner hadn't addressed--valve train and oil pump. I stacked head gaskets to reduce compression, but I guess that didn't help enough. Now that I am old, my plan for the car is just driving it to visit people, to muscle car meets, and occasional "spirited driving."

    Current setup: 69 430 bored .010 with stock heads, valves, crank, pistons and rods, with Hooker headers, B4B intake, Holley 850, Kenne Bell C107 cam, Kenne Bell push rods & roller rockers and hi-volume oil pump, Tremec TKX 5-speed, stock open rear with 3.42. Engine rotating assembly was internally balanced. Heads and deck were milled so much that the intake manifold has gaps.
  19. Bens99gtp

    Bens99gtp Well-Known Member

    Well most temp guns stop reading around 500, ill bet your close to double that. When I had a swing dist I commonly saw egts over 1000 at idle.........with a locked dist and crank retard.....its still cranks ar like 12 but just put back to full timing say 32.

    Sounds like a little investment in iron that's not been cut so much will go a long way, or maybe even some aluminum heads, they transfer gear much faster and can handle alot more compression on lower grade of fuel.......without actually knowing some info like head cc, deck height we are are you even know if its a flat piston or dish in there.???

    But it sounds like you have a tried alot so without changing or fixing the root issue the problem might not ever go away
    69GS430/TKX likes this.
  20. 69GS430/TKX

    69GS430/TKX Silver Level contributor

    Thanks for the extra info. I will look into locking out the distributor, and installing an MSD Start/Retard Control. I think that would help me a lot. I don't really want to make any expensive changes to the engine unless I absolutely have to. I rebuilt it when I was in my 20s, now I'm in my 60s and I don't want to tear down the motor again. I just want to enjoy it as is, if possible.

    Good question about the pistons. IIRC, they are stock, so kinda dished, but when I installed the new cam it was recommended to notch the pistons to ensure valve clearance, so that's what I did. Sorry, I never cc'd the heads or measured the deck height.

    I would love to do some upgrades like aluminum heads, forged pistons/rods/crank. But I already emptied the piggy bank buying the Tremec, and I'm saving up to buy paint for the body, so unless Jan gets tired of the motor in his car, and wants to give it to me, other performance goodies will have to wait. :)

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