Stalling at the touch of the pedal...

[Guitar.Slave]

So far I've rebuilt carb with adjustments to float and metering rod, new fuel filters, new air cleaner, distributer cap, rotor, spark plugs.

Still getting the same issue. Starts great, idles great touch the pedal and it falls on its face. if I tap-tap-tappy the pedal I can get it past the stumble and it responds just fine. when I let it fall back to idle and then touch the pedal it fumbles and will stall if I don't pull my foot off. (touching the pedal as in a toes weight on it).

Was headed to the lake when this started, (then it would take half throttle before stalling on the road). babied it 25 miles towards home (with the issue progressing for the worse) and still had to pay the tow truck for the last 6. Playing with the throttle while cranking quit working.
I have an electric pump, new mechanical is in the box ready to go on tonight with new plug wires.

It had been 24 hours since starting it when I took the carb off for the rebuild, and there was a puddle on the floor of the intake. like some atomization issues or some serious flooding was going on. I think this is a clue (lol)

I haven't pulled the tank to clean it yet, it has a good idle, and idles forever.
I haven't done a vac check, and am wondering if this could be a intake valve issue, or timing (which i'll do tonight with the new plug wires).

carb's a Rochester monojet, remanufactured new 2 years ago. engine is a 292 bored 0.40 overwith Langdon's cast headers. Been running great all winter.

[leftybass209]

I think you're on the right track to check timing and the other things you mentioned. I'm assuming you haven't converted the 6 to HEI? If not, then you can check for corrosion as well. Best of luck finding your problem!

[Greasey Harley]

First, check for vacuum leaks.
If you don't find any vacuum leaks. Did you blow out all the circuits with compressed air or carb cleaner, and verify that they were all clear? A clogged "off idle" circuit can also cause that problem.
I'm assuming it runs fine, other than the off idle stumble?

[67ChevyRedneck]

Originally Posted by Guitar.Slave

I have an electric pump, new mechanical is in the box ready to go on tonight with new plug wires.

You have en electric fuel pump on a 292???

How long has that been on there? Carbs only need like 6-7 psi to run. Electronic fuel pumps make like 40-60 psi.

[70 shop truck]

I'm sure you have checked this but... You might need to check your linkage on the carb accelerator pump. Sometimes when carbs gets rebuilt it needs to be adjusted.This can cause the hesitation and flooding when you hit the gas but will not impact engine idle. I would also think that the float's aren't adjusted correctly if you have fuel gathering on the manifold around the carb.

[EARNHARDT#3]

Originally Posted by 67ChevyRedneck

You have en electric fuel pump on a 292???

How long has that been on there? Carbs only need like 6-7 psi to run. Electronic fuel pumps make like 40-60 psi.

There are plenty of electric pumps on the market that are designed for carburetors and only put out low pressure.

[67ChevyRedneck]

The fuel leak made me think it was maybe sending too much pressure?

Unfortunately this could be a multitude of issues, or just one...

[Guitar.Slave]

67ChevyRedneck the electric fuel pump is 3-5 psi. going back to mechanical anyways

leftybass209 no points but not HEI (I don't understand it, but more than 5 mechanics say that's what I got.)

fuel was collecting inside the manifold prior to rebuild and float adjustments (it was lower than spec sheet said = less fuel)

new mission, self educate about accelerator pump! search bar here I come!.

Greasey Harley It idles great, responds great if I force it through the stumble. but if it drops below 800 rpms I get stumble when I just tickle the gas pedal

This issue is why I rebuilt the carb. not a result of it. and after the rebuild it is having the same problem although it does sound happier.

Thanks everyone!

[Guitar.Slave]

circuits were blown out with B-12. didn't run guitar string through the holes though.

[Guitar.Slave]

Alright, didn't find much about accelerator pump, but I did read up about plugs not being gapped right causing funny stuff like this.

When I replaced the plugs I noticed the gap was about 20. it ran good that way. napa said go to 35 with the new plugs, I ran a little perkier and now this.

with HEI gap at 60, and points at 35, and me not having hei or points, I'm a contributor is the plug gap.

any pointers? sounds like I got a bit of diagnostics to dive into.

[Guitar.Slave]

New accelerator pump came in the kit, the springs weren't in best shape though, and the plastic clip on the idle vent adjustment screw was cracked. I was and still am hoping that's a non issue though

[70 shop truck]

while you don't have a edelbrock carb they do have some of the better basic tutorials on troubleshooting on youtube.

[Guitar.Slave]

youtube'd for a while, general diagnosis, repair, and assembly is all there, haven't found anything showing my issue though.
oh youtube.

[70 shop truck]

Try this link to edelbrock carbs trouble shooting guide. It might be helpful.

https://www.youtube.com/watch?v=CQ4hqoJbtRs

[Guitar.Slave]

Thanks for the link, that's exactly what I needed.
Sounds like idle mix screws got dirty.
Accelerator pump was replaced and I'm getting the same result. I bust out the guitar string and poke all the holes a few times and hopefully that clears things up.

I'm not surging when I tickle the pedal like described in the video, it dies like I push the choke all the way closed or its instantly being completely flooded or starved for fuel. if I play with it it behaves and responds fine until I let it drop to around idle again.

I'll have someone watch the lines for collapse but with the electric pump I shouldn't be getting a collapse.

Thanks for the responses everyone! just gonna start doing a completely thorough check of everything since this doesn't sound like typical carb issues.
Cheers to doing it right the first time!

[swamp rat]

I havent worked on a rodchester for many years but take a look at the edelbrock video where he's hooking the rod up on the accelerator pump actuating arm, see how it has 3 holes and he put the rod in the middle? by moving it to the upper hole (closer to the pivot point) it makes the accelerator pump plunger move quicker pushing a little more gas into the accelerator circut, if the Rochester has more than one hole to choose from give it a try.

[kda2000]

The symptoms you describe sound exactly like the accelerator pump not working -- and "feathering" the peddle to get it off idle proves the main jets and circuit work, and the fact it idles, shows that the idle feed works, and is adjust close to OK. The Accelerator pump gives a jolt of gas when you transition off idle, or want to accelerate under load, when extra gas is needed. The way you can tell if its working is to work the throttle linkage with the engine off, as you open the throttle with it off, you should hear and smell a squirt of gas, if so the accelerator pump is working, of no squirt of gas that is your problem. -- Ken

[Guitar.Slave]

Swamp Rat I'll have to try that. I have it in the middle since it was the only hole with a key. the question is though.

what made this happen while it was driving just fine. could I have cause this with a distributor cap, rotor and spark plug change? when I pulled the plugs the were about 0.020, and I gapped them to the recommended 0.035. I don't have points, but I don't have HEI. Maybe the rotor gets out of contact when the engines shakes from the acceleration? (getting creative as the issue came within 100 miles of a plug change). Could this also be an intake valve issue? just wondering about logical possibilities.

it makes sense its an accelerator pump issue. I'm wondering if this beat up ol remanufacture has seen its days though. I'm considering upgrading. 2barrel weber (if I can get one to flow 350 cfm easy enough), four barrel edelbrock, or TBI. The latter involves a computer and electric pump and I'm taking mine off to simplify the plumbing so unless there is a huge beinfit to tbi then its a no go. I've had great reliability with the roch 1b and no issues on side slopes or the like till now when I get my first water vessel in ten years and we're hitting 85 in march.

[67 cst swb]

I second the accelerator pump as a potential issue. possibly ripped the rubber piece on assembly and its getting worse.
I also recommend the mechanical pump install.

[swamp rat]

Don't disregard post 17. If the accelrator circut is plugged it will cause the stumble. You need to be sure also that thd accelerator plunger has the blue wiper seal so the alchohol gas dosen't degrade it.

Dosen'thurt to go back thru the tune up and recheck everything.

[EARNHARDT#3]

I just went through this issue on my '67 250. The problem stemmed from a points change. Never knew you had to adjust the timing after changing points. Ear balled the timing and got it dialed in nicely. I'm new to old technology but love learning. Just finished tinkering with it an hour ago.