accelerator pump? stumble on acceleration

[Anonymous]

I have the autolite 2100 on and running nicely, but there is a stumble when I punch the throttle. I am thinking this is a fuel related problem because the carb is the only thing that I have changed, however when I look down the carb I can see gas shoot out when i work the throttle.

Could I have the accelerator pump adjusted wrong? too much gas? or too little?

or is there anything else carb related that could cause a stumble like this (bad enought to stall if I hit the throttle too hard) float level maybe?

Thanks

 

[CZLN6]

Howdy Back 64falcon200:

What is your initial advance set at? Low initial advance will add to your problem.

What holes do you have the accelerator rod in at the pump arm (the lever attached to the fuel pump) and the over-travel arm (the lever nearest the butterfly shaft). There are usually 2 holes on the pump arm and 4 holes on the over-travel arm. changing the combination of hole settings on the two arms determines when and how much fuel is delivered on demand.

Have you adjusted the low speed idle screws to achieve the highest vacuum or idle? A less than ideal setting will detract from the transition from the idle circuit to the acceleration circuits.

Is your choke functioning properly? A choke that stays on too long or not long enough can add to your problem.

Check it out and let us know.

Adios, David

 

[Anonymous]

I set the advance a 12* when i put the DSII in, I will check it again just to be sure.

I have tried the rod in different holes and it doesn't seem to make any real difference.

Do you mean the idle mixture screws or the idle speed/throttle stop screw, either way I set both by feel untill I found the smoothest idle. It might be possible that there is somthing loose and i have aslight vaccum leak. I sprayed carb cleaner around the base of the carb and couldn't find anything though.

Yes the choke seems to be working fine.

When I rebuilt the carb the accelerator pump that was in the kit seemed slightly different than the one that was originally on the carb? also when I look closely the gas shooting out is not a smooth stream and i have to work the throttle very fast to get it to shoot out nicely. I may try the pump that was on the carb when I got it. does the autolite use the same pump diaphram as a holley 2bbl?

Thanks

 

[CZLN6]

Howdy Back:

One more question- what size 2100 are you working with?

The squirt should be instantanious, steady and sustained for a short while. Anything else might indicate a plug in one or more of the tiny transfer orifaces. Clean, clean, clean... Before you look elsewhere, make sure the accelerator pump system is clean. Make one change at a time and reassess.

If you are not getting any ping or knock, try an initial advance setting of 16 degrees.

Typically the idle is lean on a 1.08 size 2100. How many turns our are the air screws? You may find that your setup requires a little richer low speed air screw setting to help cover a lean transition. IF you have a 1.14 size is is possible that the squirt is too much and needs to be leaned down by moving the rod down on the over-travel lever. The 1.14s were used on 289s but in full size cars and may be too rich for your Falcon.

Try turning each screw in until the engine begins to lose rpms, then turn it our 1 full turn.

I don't know if the accelerator pump diaphram from a Holley is interchangeable. I've never tried it. I'll look the next time I'm in the garage. The power valves are interchangeable and Holley are much more accurate and reliable.

What are the symptoms that causes you to think you have a vacuum leak? If the PV is blown it will not show up as an external leak. The symptom will be a degraded idle quality- from slightly noticeable to very noticeable.

Adios, David

 

[Anonymous]

what is the best way to clean out the holes? compressed air?