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Adjusting a Carter carb on 50' Buick?


Guest 1950SuperPDX

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Guest 1950SuperPDX

So I've been trying to get my carb / fuel mixture just right. She idols just fine, however when I put it in drive and barley touch the throttle, it kinda hesitates a little and acts like its either getting too much gas.... or too little. It feels like its pulling almost like there's some sort of something pulling...not sure what the heck that is. Even when I'm going 35-40mph it just feels like something is pulling. Then when I come to a stop, then start going again the first couple seconds of acceleration it acts up like its a fuel problem.. what do you all think?

Thanks!

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To set the jetting, for proper air/fuel mix, warm the car up and at idle, either back it out or turn it in (the jet screw) until the engine slows. To get the best adjustment ya need a tach but ya can do this by ear. After you have done one jet move on to the next following the same proceedure. Double check by going back to the one ya started with, back out or turn in until the engine slows. You have set the "jetting", now set your idle with the screw on the throttle. See if ya have the same problem. Hope this helps.

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  • 4 months later...
  • 4 weeks later...

Generally its sloppy linkage to the accelerator pump. The pump lever hasto move at the same time as the throttle linkage. Otherwise you open the throttle blades with no corresponding fuel shot resulting in bog. This assumes the accelerator pump is in good shape. Sometimes a slight straightening of the link will do it. Good luck.

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A while back, I got a call from a gentleman who had an older Buick that didn't run right and everything he'd done was "to spec", yet it still didn't run well, especially under power.

To me, it sounded like the generator system might have been hooked up with the ground not correct (on his system, hooked up as a later model "negative" ground rather than the correct "positive" ground). I'd recalled some performance issues in an old engine repair manual I have, so I mentioned them and they fit his vehicle's actions. Being a retired mechanic, he remembered the generator polarity issue after I mentioned it. Even if the system was first hooked up wrong and then re-hooked up correctly, the system will still need to be re-polarized to the correct "ground" orientation for the ignition system to work right (in some cases, fuel issues and ignition issues can act very similarly).

In some cases, a "bog" can be caused by the idle speed being set too low, which flakes-up the position of the throttle plate and the transition fuel slot in the carb's throttle bore. About .020" of the transition slot should be uncovered (at the bottom of the slot) when the carb is set for "hot" base idle. If not enough of the slot is below the throttle plate or too much of the slot is below the throttle plate, serious bogs can result . . . even with a decent accel pump shot. The transition fuel slot is adjacent to the hole which the idle system fuel (which is what the idle screw adjusts) comes out of in the carb's throttle bore (usually in the base plate).

What you are experiencing might be the combination of several things. Making sure the base timing is "ballpark", if not correct would be a start. Then making sure the distributor points "dwell" is "ballpark", if not in the spec range, would be next. Plus, the distributor's main centrifugal advance system and the additional vacuum advance system.

If the spark plugs are the correct heat range and are blackened with soot (as if the carb was running tooooo rich), then that might be a tip that the charging system polarity needs re-orienting.

Checking and tweaking the accel pump linkage so it works more accurately would be something to do, anyway. There should be a little looseness in the linkage (to help decrease frictional wear as it has no normal lubrication), but just enough to let the rods jiggle some. On some accel pumps, if you just ease into the throttle, they "dribble", but if you open the throttle quickly, then they "shoot". If there might be another hole in the accel pump linkage system that you might use, rather than the "normal" one, that might be an option, but you'll probably have to reset the pump's travel when you do that--depending upon how it's set-up. If the pump's plunger ends up being less depressed, then it might put the pump cup in "unused" territory on the accel pump's bore, which might compensate for the wear issue in that area.

Not to sound "flaky", but "Happy Hunting". Once you find the issue(s), things should work nicer.

Just some thoughts,

NTX5467

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