Carburetor help needed

1948 Pontiac, 8 cyl, 2 barrel carter carb.
Carb was rebuilt about 2000 miles ago, (12 years ago) and never really ran quite right. Cannot return, I moved out of state.

Everything runs fine except there is a 'flat spot' at about 1/8 throttle. Idle is fine, and when you step on the gas at (standing start) the engine kind of stalls (never stops) at about 1/16 or maybe 1/8th throttle. The quick solution is to step on the gas a little harder (push pedal further) when starting from a stop.

Any ideas on what circuit or what part of the carb might need some attention?

Surely some of you guys still remember carburetors!

Thanks of any suggestions.

Ivan Vegvary

On Mon, 22 Sep 2014 17:59:42 -0700 (PDT), Ivan Vegvary
> wrote:

>1948 Pontiac, 8 cyl, 2 barrel carter carb.
>Carb was rebuilt about 2000 miles ago, (12 years ago) and never really ran quite right. Cannot return, I moved out of state.
>
>Everything runs fine except there is a 'flat spot' at about 1/8 throttle. Idle is fine, and when you step on the gas at (standing start) the engine kind of stalls (never stops) at about 1/16 or maybe 1/8th throttle. The quick solution is to step on the gas a little harder (push pedal further) when starting from a stop.
>
>Any ideas on what circuit or what part of the carb might need some attention?
>
>Surely some of you guys still remember carburetors!
>
>Thanks of any suggestions.
>
>Ivan Vegvary

The first thing I'd check is the accelerator pump. Look down the
throat of the carb, engine off, and slowly open the throttle and see
if you get a fairly uniform squirt of gas coming into the throat as
you are opening the throttle. You can try it a couple times but you
will eventually pump all the gas out of the bowl. Also, best to do
this after having run the engine a few minutes to make sure the carb
bowl is full. If no consistent squirt the whole time you are opening
the throttle, esp the first part of the movement when you are having
trouble, would point to a bad pump. It's possible it's leather and
dried out. I'm not familiar with that carb but it may be pretty easy
to take the top off of it while it's still on the car to remove and
fiddle with the accelerator pump. I'm assuming it has one.... It's
also possible that the pump lever arm has more then one hole in it
that you can put the linkage in. The closer the hole is to the pivot
the more fuel it squirts for any given amount of linkage movement. So
if you can move it to a closer to the pivot (farther away from where
the end of the lever is) you can also try that to richen up the mix
under acceleration. It is also possible that your problem is caused
by improper ignition timing. You can try changing the timing to see
if that makes a difference.

Thanks Ashton.
I will try your suggestions.
Ivan Vegvary

Ashton Crusher > wrote in
:

> On Mon, 22 Sep 2014 17:59:42 -0700 (PDT), Ivan Vegvary
> > wrote:
>
>>1948 Pontiac, 8 cyl, 2 barrel carter carb.
>>Carb was rebuilt about 2000 miles ago, (12 years ago) and never really
>>ran quite right. Cannot return, I moved out of state.
>>
>>Everything runs fine except there is a 'flat spot' at about 1/8
>>throttle. Idle is fine, and when you step on the gas at (standing
>>start) the engine kind of stalls (never stops) at about 1/16 or maybe
>>1/8th throttle. The quick solution is to step on the gas a little
>>harder (push pedal further) when starting from a stop.
>>
>>Any ideas on what circuit or what part of the carb might need some
>>attention?
>>
>>Surely some of you guys still remember carburetors!
>>
>>Thanks of any suggestions.
>>
>>Ivan Vegvary
>
> The first thing I'd check is the accelerator pump. Look down the
> throat of the carb, engine off, and slowly open the throttle and see
> if you get a fairly uniform squirt of gas coming into the throat as
> you are opening the throttle. You can try it a couple times but you
> will eventually pump all the gas out of the bowl. Also, best to do
> this after having run the engine a few minutes to make sure the carb
> bowl is full. If no consistent squirt the whole time you are opening
> the throttle, esp the first part of the movement when you are having
> trouble, would point to a bad pump. It's possible it's leather and
> dried out. I'm not familiar with that carb but it may be pretty easy
> to take the top off of it while it's still on the car to remove and
> fiddle with the accelerator pump. I'm assuming it has one.... It's
> also possible that the pump lever arm has more then one hole in it
> that you can put the linkage in. The closer the hole is to the pivot
> the more fuel it squirts for any given amount of linkage movement. So
> if you can move it to a closer to the pivot (farther away from where
> the end of the lever is) you can also try that to richen up the mix
> under acceleration. It is also possible that your problem is caused
> by improper ignition timing. You can try changing the timing to see
> if that makes a difference.

also try setting the idle pretty rich and see if it helps any. if it does
then it probably is the accell pump. also check the dist mech advance is
working correctly as a slow advance will cause the same symptoms. KB

Thanks Kevin,
Found out that it hesitates at all speeds if you just step on the gas slightly. Will check the spark advance. Have spare distributor if necessary.