Stumble issue

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Johnny Dart said:
The car is falling on its face because it has the heaviest spring in it,thus not opening the metering rods fast enough,if at all in the power mode.
THE CAR IS STARVING FOR FUEL !
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I guess my understanding of the Edelbrock power circuit is flawed too. I thought the step-up pistons were pulled down the bores by manifold vacuum. Thus, a spring rated for 7" Hg (silver) would begin raising the metering rods at 7" Hg and springs rated at 5" Hg (orange) would begin raising the metering rods at 5" Hg. In a nutshell: stiffer springs start pushing earlier as manifold vacuum approaches theoretical zero.

It's not my aim to be an antagonist. I'd just like to understand how the thing really works.
 
doktor_x said:
I guess my understanding of the Edelbrock power circuit is flawed too. I thought the step-up pistons were pulled down the bores by manifold vacuum. Thus, a spring rated for 7" Hg (silver) would begin raising the metering rods at 7" Hg and springs rated at 5" Hg (orange) would begin raising the metering rods at 5" Hg. In a nutshell: stiffer springs start pushing earlier as manifold vacuum approaches theoretical zero.

It's not my aim to be an antagonist. I'd just like to understand how the thing really works.
Click to expand...

It is best to select a spring on the basis of vacuum. Same with a Holley (power valve).
This is why I asked him what his vacuum was. I have found these Ede carbs to be calibrated very close right out of the box.That is why I suggested the stock Orange spring.Half the fun is having the strip kit and test & tunning for your best set-up.
In all reality,I wish I knew how these dam things worked to.8)
 
Actually Johnny, I believe 1411's have the pump arm in the top hole. Could be wrong. I have had some cars that like the top hole and some like the center hole.
 
redfastback said:
Actually Johnny, I believe 1411's have the pump arm in the top hole. Could be wrong. I have had some cars that like the top hole and some like the center hole.
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Steve,looked it up,you are correct.Top hole.This will explain the stumble off idle. As you know,going to the center hole will give the carb a bigger shot of fuel,and going to the last hole (towards carb) even bigger yet.

Another note here. The 1411 750 (electric choke) carb is set-up different than the 1407 750 (manual choke) carb. It is set-up with more economy in mind,(smaller main jet/metering rod).If it was my carb I would set it up to the 1407 specs. Simple main jet/rod change.
 
Ok, heres what I tried today. Took top off and checked float specs which are good. Has stock 1411 main and secondary jets in. I do not have the stock metering rods so I tried closest that I have with orange springs. Also checked choke. Works good and opens fully once warm. Next I went to middle hole on pump (was in the top hole). After all that it still stumbles. I even tried the weakest spring just to see what would happen and it stumbled really bad, almost stalled. Dont know what to do next. Its only when I either pull out from a stop or when Im just barely touching the gas when cruising. If I punch it from a stop or when driving it takes off like crazy. Dont know what to try next.

Josh
 
Did you blow the carb orfices out with carb cleaner and compressed air ?
One spec of dirt in the wrong place can dog any carb.

Stumble from a complete stop usuaslly is related to the pump.Might be you need to replace yours.They are available from Edelbrock.

Are you getting a good shot of gas when you hit the throttle,and is it instant ?

How did you measure your floats ?
I usually set mine a tad higher than what they ask for.
 
I was just gonna say, where did you measure float drop from. That is VERY important.
 
Johnny Dart said:
Did you blow the carb orfices out with carb cleaner and compressed air ?
One spec of dirt in the wrong place can dog any carb.

Stumble from a complete stop usuaslly is related to the pump.Might be you need to replace yours.They are available from Edelbrock.

Are you getting a good shot of gas when you hit the throttle,and is it instant ?

How did you measure your floats ?
I usually set mine a tad higher than what they ask for.
Click to expand...

Yep, I cleaned it out. With the car off and manually twisting the throttle it seems to me like it gets a nice shot of fuel and it looks instant. I used a 7/16" drill and just used a 6" rule to measure the drop. I understand that it could be the pump when it bogs off thr line, but what about when Im cruising at very light throttle and I can feel it stumbling? Thanks for your patience and helping me out guys.

Josh
 
69dart440 said:
Yep, I cleaned it out. With the car off and manually twisting the throttle it seems to me like it gets a nice shot of fuel and it looks instant. I used a 7/16" drill and just used a 6" rule to measure the drop. I understand that it could be the pump when it bogs off thr line, but what about when Im cruising at very light throttle and I can feel it stumbling? Thanks for your patience and helping me out guys.

Josh
Click to expand...

Look at your chart and go 1 stage richer (cruise mode) untill the bog goes away. Hopefully you will be able to do this with just a rod change.

You can try a new acc pump.Looked up the part # for you.Then you know the pump is good.

Edel Accelerator Pump Part #1467 $8.50 Summit.

Would still like you to get this carb to exact specs out of the box,and go from there.With the new Acc Pump.

One other note.There are countless times when the carburetor is blamed for a faulty running car. When in fact it can be a number of different things.
Ignition,coil,wires,cap,rotor,timing,vacuum leaks. I will assume all these have been taken out of the equation.
 
I had almost the same problem when I pulled off a 800 Thermoquad, and bolted on a 625 AVS Carter on my 360 Duster. The 625 AVS was just to small, and I didn't have any tuning parts for a AVS. I had a used 750 Vac Holley as a back up, and it runs great. Try a different carb!
 
doktor_x said:
I guess my understanding of the Edelbrock power circuit is flawed too. I thought the step-up pistons were pulled down the bores by manifold vacuum. Thus, a spring rated for 7" Hg (silver) would begin raising the metering rods at 7" Hg and springs rated at 5" Hg (orange) would begin raising the metering rods at 5" Hg. In a nutshell: stiffer springs start pushing earlier as manifold vacuum approaches theoretical zero.

It's not my aim to be an antagonist. I'd just like to understand how the thing really works.
Click to expand...

You are correct, the stiffer spring is for a sooner opening or raising of the needles. Going softer will keep them closed longer as the manifold vacuum is what pulls them down.
 
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