Adjusting pump shot

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RobbAdams

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Looking for information on how to properly set this up. I have to very gingerly press on the pedal, or the thing bogs out to the point it sometimes actually stalls out.

How do you tell if you have to little or too much?

Holley 670 Street Avenger, most motor details are in my signature.
 
Hey Robb......Just another direction here,,,check your vac. advance as well. Not having enough vac. advance just off-idle will exhibit the same symptoms. Ask me how I know.

Just my thought...
 
There is to ajustments you can make. One is to move the pump rod to one of the three holes. If that does not work then you can change out the acc pump with a different one. To ether put in more gas or less gas. Then try moving the rod around again untill you find a combo that works.

As far as to little or not enough? It is hard to say as not enough gas will have the same simptoms as to much gas. It is just a trile and error thing.
 
I have the Vac Advance on the port that is just above the adjustment screw, where the metering block would be. Is that the right port?

I have a vaccume guage, but not sure what kind of readings I should be getting, or how I should test the output ( at idle, at a certain RPM etc)

Instructions would be much appreciated.
 
First off, check timing, set curb idle to highest vacuum level.

Then you take that vacuum reading in gear, see what it is. Your power valve should be 2 hg below what your reading is. The front bowl needs to be removed to accomplish this. Those carbs usually come with a 6.5.

After that, the only true way to check the pump shot spring to acc pump arm is with the carb off, and check for .015 of clearance. But since it is on the car, just adjust it out 1 full turn, then drive it. Worse or better? Then go back to your initial setting then adjust 1 full turn in. Worse or better?

You may have to buy a acc pump cam kit and try different ones til you find the magic one.
 
You've got the right port. Attach your vac gauge to that port. There should be no vac at idle, but it should come on quick as you advance the throttle. Also check and make sure that the vac diaphragm (pot) on the distributor is actually working. If the diaphragm springs a leak, you wont get vac advance at all. I check the vac pot by applying vac to the hose that leads to the pot, with either a vac pump or suck by mouth. If the RPM's increase, then the pot is functioning.

If all thats working fine, then I would assume its at the carb. The pump shot on a Holley is adjustable at the throttle arm. If you look on the side of the arm, there should be a small number "1" and a "2". The plastic cam that the accel pump lever rides on is adjustable there. Also make sure you have minimum clearance between the spring/bolt on the end of the accel pump lever and the pump arm.
 
OK to make sure I understand, I will set the timing (initial) at idle with the vaccume advance disconnected from the Carb and the port blocked.

I then adjust the distributer until I get the highest vaccume reading without detonation.

What port on the carb should I be taking the reading from for the Vac Gauge?

once initial Timing is set, if I still have a problem then what?
 
ok one more question, no one has discussed squirters for Accel. pump. do you mess with the cams first, or the squirters?
 
With the size cam you have, I doubt you need a bigger squirter. You probably have a 25 in there. Maybe try a 28 or 31, but I would mess with the cam first. Like I said, the cam in there may need to be changed to one from the kit.
 
Turns out the pumpshot arm was advanced too much, cranked the little Screw/Spring thing back a couple of turns and everything is good, thanks for all the help.
 
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