Tuning troubles

[D35 Torpedo]

It all started when the weather warmed up. Hind-sight, I think the problem then was the accelerator pump setting. Anyways, I chased the problem. Tried everything under the sun. I ended up reusing the carb gaskets to many times and had a vacuum leak. Fixed it and still had issues. So now, I've done so many thing that I really am at a loss. At first It seemed like it would run out of gas when I run through the gears to fast, like a weak pump. The diaphragm is only six months old. I didn't replace the valves. The pin hasn't moved. Did some more messing around and now off idle it caughs. Tonight, I realized that it is a lean condition. I pulled the top and removed the accelerator pump and disassembled it. Removed the spring behind the leather and stretched it a bit. I also stretched the big spring on top of the pump a bit. I get a good shot immediately now where as before there was a dead spot at first. It's better, but still has a hesitation. And after the hesitation the power really lurches to life. I've swapped distributors with no change. I've played with the timing and float height. I just pulled the intake manifold, replaced the gaskets and blocked off the heat riser. The car fires up instantly, and pulls good. It just doesn't like to take off without hesitating. The throttle shaft play was excessive. I peened the boss around the shaft and that got rid of a bunch. I also put O-rings on either side to stop vacuum leaks. The carb is an E7T2 carter BB. Any tip, tricks or advice is welcome. I am running out of ideas. I like this carb because it has a large bore. It did run good. So I'm not in a hurry to swap it out. Thanks gang.

Edited June 15, 2023 by D35 Torpedo

[Booger]

Using corn gas tends to dry out gasket around accelerator pump plunger. Booger will do the hesitation/flatspot thing sometimes. Maybe try to richen mixture with main jet?

Take the pledge. NO CORN GAS!

[Plymouthy Adams]

83 years later and people still don't like it....!

Edited June 15, 2023 by Plymouthy Adams

[Sniper]

There are three adjustment holes for the pump shot.  Which one are you using?  Have you tried any of the others?

 

[vintage6t]

57 minutes ago, Sniper said:

There are three adjustment holes for the pump shot.  Which one are you using?  Have you tried any of the others?

 

A bit more info - rule of thumb is the one closest to the shaft is typically the summer setting - least amount of squirt, middle cooler temps, position shown is winter - most amount of squirt.

[D35 Torpedo]

11 hours ago, Booger said:

Using corn gas tends to dry out gasket around accelerator pump plunger. Booger will do the hesitation/flatspot thing sometimes. Maybe try to richen mixture with main jet?

Take the pledge. NO CORN GAS!

I run corn free chevron 94. Thanks

 

3 hours ago, Sniper said:

There are three adjustment holes for the pump shot.  Which one are you using?  Have you tried any of the others?

 

I was on the summer shot, but last night I went back to the middle.

[FarmerJon]

So carb is a higher CFM B&B from a truck or marine application, and it ran well until it sat over winter,  correct?

Hesitation is mostly during accelerating, not at cruise?

 

If so, I would think that something has gotten gummed up. You might be able to pull your accelerator pump back out, check that the balls are free and clean, spray out the passages, and clean the squirter jet.

I would also clean and check the vacuum piston and step up piston for free movement.

 Check for vacuum leaks at the body gaskets.

 

If problem started with the larger carb, maybe it needs a larger squirter jet.

Good luck!

[D35 Torpedo]

Ok guys n gals. I figured it out. Turns out when I was swapping stuff around, I put a stiff step up spring in. I just realized it and swapped it back to the original one. It's a hard lesson to learn, and somewhat surprisingly contradicting to what I thought was the problem. I used the choke method to figure out it was running lean. But changing the step up spring to a lighter one has solved the problem. A lighter spring keeps it lean longer...anyways, it seems the step up circuit plays a huge roll. A lot of driveability is wrapped up in the step up. 

[Sniper]

Now see how it runs on the leanest pump shot.  No reason to put more fuel in than you need. 

[D35 Torpedo]

Now for an update

 

She's running better, but a problem still remains. At steady cruise I get a sputter and surge. I really think it's the step up hunting around. I need to brap the throttle quickly before taking off or it will stutter a bit as well. The car runs better at night when the air temp cools off. I replaced the step up and piston with another one. The original needle had a step worn into it. The new needle is a few thou larger with no wear.