Vacuum Question

[strat1960s]

I am trying to go through a list of items that may be causing my car to die when I stop at a light or intersection. Six starts to travel 12 miles.
Here is a list of what I think may be causing the motor to die:
Incorrect vacuum at the dizzy.
Timing may be off.
Engine idle speed may be too low/high. (set at 1300 +/-)
Idle jet may be too small/big.

Ok, From my understanding, the regulated port on my Weber Carb is supposed be connected to my dizzy. I have noticed that if I disconnect the vacuum hose at the dizzy, the RPMs drop a little, but it seems that my stalling problem goes away. I will try my little test again over the weekend, but last weekend when I was fiddle farting around with it, that is what happened. What could be causing this?
Thanks for any help.
Ted

 

[BIGREDRASA]

Start by advancing the timing a couple of degrees at a time. When it starts pinging, back it off one.

 

[Anonymous]

First off unhook the vacuum advance and plug the port. You need to set the timing . Then adjust the idle speed and recheck timing, 1300 is way too fast. Idle sped should be 600-800 max. adjust up(outward) the air mixture screw to achieve the correct idle then go back and adjust the timing again you'll see a real difference and hear it.. Always err on the side of rich mixture. Less Ping, smoother idle better response and extra gas cools the engine which youy should feel immediately when under the hood.
Put a vacuum gauge on the motor after you get idle and timing correct.
Run the air adjustment screw in or out until you get at least 14 psi vacuum. 15 is what you'll need to pass emmission and get any kind of mileage and performance. This is what keeps the oxygen to fuel ratio correct. anything above that 14 shows a new engine or well tuned and running. Don't ever try to tune a carburated engine without the aid of a vacuum gauge.

 

[CobraSix]

I would not do the ping method of timing while you have this problem. Just set the timing at 12* BTDC at 600 RPM. Do the ping method later if you really want to. Be sure to verify that TDC on your dampner is correct. Do a search, it's been discussed here before, I think you have done it before, just can't remember. Hook up the vacuum gauge, timing light, and tach to your engine. slowly dial back the timing until the point the car doesn't really want to run. Then adjust the carb to run the idle speed down, readjust the timing, then readjust the carb, until you get to the point where yoru RPMs are around the 600 point (650-800 I think for autos).

I disagree that you have to have a vacuum gauge. It's nice, but after you've tuned awhile, you'll find you really don't need it, if you have a timing light, and a good ear (or tachometer). This is the way I tune, and I've found it corresponds almost perfectly with a vacuum gauge. slowly turn the idle mix screw clockwise (leaning out the mix) until you hear the RPMs drop (remember, this is done at your correct idle speed, not 1300). then turn counterclockwise until you hear the RPMs start to drop again (or see the tach drop). Now, turn clockwise the idle screw until you hear the RPMs drop (yes again). This time though, count the number of turns it took to make the RPMs drop going clockwise. Now turn counterclockwise between 1/2 turn to 50% of the total amount of turns it took to make the RPMs drop. If you pop a vacuum gauge on at this point, you should find that you are at 15 or so for vacuum. This is just a lot quicker way or retuning idle on the side of the road (don't ask).

Slade

 

[Anonymous]

Well put. I liked the way you explained it..ZZ