[Player]

Would an Accelerator Pump only act up under a load like this? And if so, can those be purchased individually (not in a kit)? I'd be a little upset if my new one is the problem.

[Player]

Ok, I'll self-diagnose this. Maybe I'll try advancing the timing some more and see how it responds.

[Player]

I advanced the timing to about 12. Seems a little better (ie it's not dying on me) but it still hesitates if I don't give descent throttle. Not sure if I should advance it any further or move on to some other culprit...

[v8only]

Is your accelerator pump arm adjustable?? On my holley carb, the accelerator pump has an arm and a spring....with an adjusting screw.

I had the exact same off idle bog, and I found that when I was putting my foot into it, right off idle, the accelerator pump wasn't squirting gas. The linkage had maybe 1/8 inch or more gap where you'd stab the gas, but didn't see the squirt of gas.

by loosening up the adjustment, the spring too up the extra slack.

pull the air cleaner off and stare right down the top of the carb. Hit the accelerator gently. RIGHT Off idle, the INSTANT you hit the gas, you should see a squirt of gasoline go into the carb. If there is a little bit of play before you see that squirt of gas, then you need to adjust your accelerator pump until it squirts gas the second you touch that accelerator. don't over adjust or you;ll get a constant stream of gas at idle. should have no squirt of gas at idle, and a squirt with slight gas pedal pressure

[Player]

The adjustments that I have available to me can be seen in the attached pics. I don't think I can adjust it quite as you described.

Do you mean that I should take the top of the carb off so I can see inside (where the float is)? Or is the fuel from the Acc Pump squirting direc directly into the venturi chamber below the butterfly valve?

[v8only]

wow, old school 2100 carb.

not sure if that's adj?

just look down the top while it's running and make sure the acc pump squirts fuel in instantly after you hit the gas. You'll see the fuel squirt in. This was the reason behind my bog, but my holley is adjustable...not sure if that old autolite carb is or not, it's been some time since I messed with them.

[Player]

Where do you see it squirt in? Under the butterfly valve?

[v8only]

just go out and try it, you'll see it...just under the choke plate towards the top of the carb....stab the throttle linkage on the side of the car, and you'll see fuel spray into the carb...can't miss it.

car doesn't have to be running, but you may flood it out doing this...

[Player]

I didn't realize it didn't have to be running...interesting.

I'll check it out and let you know.

[v8only]

that's how you flood your car by pumping the gas too much when it's not running...as the carb is still squirting gas every time you pump the pedal even when it's off.

[Player]

That certainly makes sense. Before I learned about the Acc Pump, I wondered how the carb would get flooded when the pump wasn't running...lol

[v8only]

Yea, a carb is 100% mechanical.

It stores a reserve of fuel in the float bowl. When the car is off, you could literally pump that gas pedal until you empty the entire contents of the float bowl into the engine.

As for how this circuit works.....at idle the throttle plates on the very bottom of the carb are pretty much closed. I know there is also a small hole drilled in the bottom throttle plates to allow fuel into the motor at idle, since the throttle plates on the bottom are closed.

While idling, the accelerator pump is at rest, and no fuel is being added to the carb. This is where the idle screws in the front come into play. If you adjust them counter clockwise, they'll allow more fuel to flow in through the other circuit...towards the bottom (I'm just re-learing this all too).... This is how you can run too rich or too lean at idle, as fuel is being let into the engine at idle via those screws in front.

When you step on the gas, the idle circuit can no longer provide enough gas, so the accelerator pump off the front, attached to the throttle linkage will provide a big squirt of gas into the engine the second you stab the throttle. This quick squirt of gas provides what the engine needs to get going. If there is slack in your adjustment, then you step on the pedal, and nothing happens. You don't get your squirt of gas, and the car doesn't go.

Tuning the carb therefore is a complete package, and require a balance between the right idle speed, the right accelerator pump adjustment, and right idle mixture.

It's kind of fun for me, as I'm a fuel injection guy, and have been dealing with the fuel injected 5.0 engines for the past 15 years or so. I've just NOW built a 66 mustang with a carb'd motor, and have had to teach myself carb's. I'm far from an expert, but I've so far learned enough to dial out the richness problem I had, and that bog that I had. Now I'm trying to teach myself about the rest of the carburator so I can figure out the slight surging problem that I have on occasion.

[Player]

There's certainly an art (or science) to tweaking carbs. And I have A LOT to learn.

With all that EFI does to simplify things, why didn't you just fuel inject your '66 when you rebuilt it?

[v8only]

I'm actually doing a full resto on our 72 maverick that my mother bought new. It's got a 5.0 going in, and I decided to go EFI fuel injection on it.

As with the 66, I car'b it initially to get it going quicker. This 66 is my beater fun toy, and I want it to be the car I thrash at the track. Carb'd cars are a BILLION times cheaper to modify for speed. You've got an intake and a carb. Lol. With efi, you've got the upper and lower intake, the fuel injectors, the fuel pump, the throttle body and spacer, even the mass air meter too, then you've got to make sure it's all tuned and dialed in with the computer.

I did that with my 86 for years and loved it though.

I am getting slightly fusterated at how inconsistant the carb is on the 66. I may eventually go efi on it. I mainly wanted to learn all the ins and outs of carburation though before I went efi. I fealt I was short changing myself by knowing EFI and being clueless about carb'd cars.

[Player]

This is getting off topic a bit...but do you have any info on what all is involved with tuning EFI? I've been looking at switching to EFI, eventually. I'm planning on doing all the upgrades that I want done and hooking up the EFI at the same time. Then tuning it to that setup and calling it good. Just not clear on what "tuning it" entails.

The rebuilds I've done in the past (modern, foreign vehicles) I didn't really upgrade anything, just took them apart, replaced some pieces, had some parts machined, and put it all back together. Not any tuning involved.