# 326 Acceleration



## chui1980 (Jun 5, 2013)

Ok so some people here may already know that this car was garaged for over two years without starting. I finally got her running and off course I did the obvious. Change all fuids, filters, etc. New spark plugs as well and even just recent a pertronix conversion kit. With all that said she still stumbles a bit off the line. Once running pick up is relatively fair considering it is a powerglide. My question is what could be causing her to act like this. It is a two barrel by the way


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## Goat Roper (Oct 28, 2014)

Timing, advance or possibly the accelerator pump.
Remove the air cleaner and check how the pump works and if it is squirting good then it is the timing/advance.


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## chuckha62 (Apr 5, 2010)

Remember this old adage: 95% of "carburetor" problems can be fixed by adjusting the timing.


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## oldskool (Apr 26, 2015)

chuckha62 said:


> Remember this old adage: 95% of "carburetor" problems can be fixed by adjusting the timing.



Actually, I've found just the opposite to be true. I ran Q-jets. Most of the time, any stumble, bog, or hesitation was caused by a poor pump shot, or the secondary air flap either opening too quick, or not quick enuff.

Now, since you have a 2-barrel, I think we can safely rule out any problems with the secondary air flap. :lol:

So, the very 1st thing I'd check is the pump shot. It should start shooting as soon as the throttle lever moves, and continue a good strong shot, as long as the throttle lever continues to move towards the fully open position.

http://www.thecarburetorshop.com/Troubleshooting.htm#Acceleratorpumps

The corn squeezins in pump gas nowadays will render the old rubber type fuel pump cups useless, sometimes in a matter of hours. There are some cups made nowadays which are supposed to be more ethanol resistant. I've read that some do a better job of this than others. 

Some are rated for straight achohol use. I assume these would be the best available. 

2G Carburetor Accelerator Pumps - Carburetor Parts & Kits for Carter, Ford Motorcraft, Holley & Rochester Carburetors

http://www.carburetor-parts.com/2G-2GC-2GV-Carburetor-Parts_c_140.html

http://www.carburetor-parts.com/Rochester-Accelerator-Pump-Cup-34_p_2538.html


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## chuckha62 (Apr 5, 2010)

Certainly ascertain your accelerator circuit in your carb, but do not underestimate the effects of lazy timing. The difference between 8 degrees before and 12 degrees before can make all the difference in the world.

Now, to be accurate, you should set the total timing at 36 to 38 degrees and let the initial fall where it may.


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## rickm (Feb 8, 2012)

setting the timing @ stock specs the car should not stumble at all. start there. its a 2-barrel Rochester. after that if it still don't run right go thru the motions n find whats wrong.


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## Lemans guy (Oct 14, 2014)

Solid advice all,....Is the stumble all the time? Or just during cold driving?

There is lean stumble and rich hesitation, that feels like a stumble. Sometimes coming off of idle with a gentle pedal applied, and therefore no big pumps hot the car bogs. 

At that transition spot the mixture may lean too much as you open the throttle flaps. have you tried just enrichening the two idle screws a quarter turn or even a half, and see if the bog improves....or disappears. You may have the idle set A little lean....

Small changes can fix this sometimes. now if it only happens during cold operation than you have to get the choke and fast idle cam set up just right, that can cause a bog as well.

But I agree timing is always critical to get it smoothed out either way....


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## chui1980 (Jun 5, 2013)

Teh stumble is at all times. I just noticed also that it is counter clock wise rotation and some spark plug wires are comming off loose at the spark plug connection. I will change all wires to new 8mm and then start checking timming. Also I am waiting for the aluminum intake to convert into 4 barrel. I have a working rochester quadra jet siiting aside for the car. I think I should not spend any time setting with two barrel for now. thanks so much guys. I will keep all posted


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## ALKYGTO (Mar 29, 2010)

Personally I would get the car running properly now. You may have a different set of problems when installing the 4 barrel and compound your issues. The two barrel is very simple . Do some basic trouble shooting and clean it could solve the carb problems. Get the ignition system tuned up with new wires, make sure the cap, rotor,coil and plugs are in good shape.


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## geeteeohguy (Feb 2, 2008)

Remove the air cleaner. Start the car and let it warm up. Gun the throttle with your hand, under the hood a bit, with your head out of line of the carb. (you want to keep your eyebrows if it backfires). If it bogs/sags/hesitates, try doing the same thing but squirt a blast of carb cleaner down the carb while doing it. If the bog goes away, it's too lean and it's your accelerator pump. Today's alky blended fuels eat up the diaphragm of the pump. My gut tells me you have a bad accelerator pump......


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## chui1980 (Jun 5, 2013)

Tallk about upset. I replace the factory intake manifold with an aluminum type the q-jet and now the car gets. Once it warms up the gauge starts going all the way up to 250-280 so shut it off. The new gaskets and manifold do not have the center holes to match the heads since it if for the element on the choke for the 2 barrel. I just don't know how the hell this happened just like that. I will remove the thermostat to see how it behaves.


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## oldskool (Apr 26, 2015)

There is nothing about the water crossover part of an alum intake that is any different than an iron 2-barrel crossover, which would cause overheating.

As quick as you say it gets hot, I think you are on the right track with the thermostat. Obviously, the water is not circulating. But you don't want to run without a thermostat, or some kind of restriction in it's place. The water will flow too fast, thus the system can not extract as much heat from it, as when it flows a little slower.

We always ran a gutted thermostat in our race cars. You might try that. If it cures your problem, then you can buy a new 160 or 180 degree thermo. Like most other car parts, thermostats fail. A thermostat that won't open is quite useless. I've often read that the best way to check if a thermo is working is to put it into a pot of water, on a stove. Turn the heat on high. The thermo should open fully, before the water starts boiling.

http://www.wikihow.com/Tell-if-Your-Car's-Thermostat-Is-Stuck-Closed


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