vacuum pod on choke not releasing

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pinkfuzzibunnies

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hello, i have a 75 dodge dart /6 with a 1945 holley carb. So my carbs choke is sticking and won't drop down on the cam, it does open up eventually because the thermostate pulls it open. I finally saw what was the hang up today - my vacuum pod is not releasing, it stays sucked in the whole time.

What is causing this?

I had thought when the vacuum was shot it just didnt work at all so thats making me think somethings plugged or wrong with the vacuum lines somewhere. I've checked them and couldn't find anything real noticable.

As always Thank You. You all are helping me so much and it is so great to actually know what I'm talking about now and troubleshoot a problem!
 
I'm not understanding the question or problem.
A primary choke pull should provide only the intial air gap for cold start. The rest of the movement comes from the heat. A primary choke pull should pull all the way back and stay there until the engine/vacuum stops.
 
RedFish said:
I'm not understanding the question or problem.
A primary choke pull should provide only the intial air gap for cold start. The rest of the movement comes from the heat. A primary choke pull should pull all the way back and stay there until the engine/vacuum stops.
Click to expand...

from what i understand it should also pull choke off if the vacuum gets high enough, as if you started driving so its not flooding out...
 
805moparkid said:
from what i understand it should also pull choke off if the vacuum gets high enough, as if you started driving so its not flooding out...
Click to expand...

I'm not sure on the later models. Some carbs had a secondary vacuum choke pull to open the choke. Some had a lever in the throttle linkage to open the choke.
 
have you checked the choke unloader tang ? RedFish is right in his post as to how the choke vacuum diaphragm works.
 
well....umm...so i have a little vacuum pod that is connected to the step cam. Before when I would start up my car (cold start) then it would be on the highest step on the cam...so I'd give it a little gas and it would drop down to the next step, give it a little more it drops again til it's on the last step this occuring because the little vacuum pod thing would release when I pushed the gas pedal. Then after driving a bit, like a block or two, the thermostate would take over and pull the choke completely open......I hope i'm explaining this correctly...but now, what happens is that little vaccuum pod never releases at all when I step on the gas so my choke is on much longer, it slams into gear, and it's blowing through gas until the thermostate pulls it open...I have not changed any vaccuum lines or anything, just one day it didn't work right and hasn't since.

I suppose it's not a big deal, I can just lower the rpm on the fast idle screw so at least I'm not slamming into gear when I first start up (shrug) I just wanted to know why it's not releasing....i have a holley 1945 if anyone needs that info. Thank you!
 
hot stuff: I've heard about the choke unloader, i'll have to look it up and read up on it if I can find the info, I'm a newbie (clearly) so I'm just learning as I go. Carburators are quite complicated to me, I have zero mechanical background so when I have a problem I just try to find someone or a website that can dummy it down for me. :)
 
You really should watch the choke heater slowly open the choke. That's what lets it off the steps. Somewhere around 74 they added an electric choke assist which was just a heating elecment to speed up choke operation. When that heater failed their choke went back to slow operation. They filed your complaint.
 
pinkfuzzibunnies said:
Carburators are quite complicated to me, I have zero mechanical background so when I have a problem I just try to find someone or a website that can dummy it down for me. :)
Click to expand...
Carburetors are very complicated to me too and I am a mechanical engineer that once designed turbine engine fuel controls. Your 1975 is much more complicated than my 64 & 65 carbs, but even in my simple ones I never know exactly what is going on inside. At least your problem is on the outside where you can see the operation. BTW, learn to spell carburetor before you post one on ebay or a troll like me will find it mis-pelled, buy cheap and sell for $100 more, like I did a few times.

I remember telling you "check the choke pull-off" several times over the last 2 months and you finally found something. However, I have no idea what yours looks like and sounds like there are several. Can you post some closeups because I suspect that most of us have never seen exactly what you are dealing with.
 
LOL...that's funny with the made the complaint thing...and that I'm spelling carburetor wrong (but no one would get one over on me when it come to ebay, i am great on ebay mwahaha) I've had the thing working perfect several times over the course of owning it, and then it seems like one day I go out and everythings messed up again

Hope this image works, this is what mine looks like but theres the additional choke thermostate coming off of it that bolts down on the manifold

nrc1378-1.jpg


016.jpg


this is a pic of the other side....LOL this was when gas was leaking out of it....we fixed that...
 
Your carb doesn't look more complicated than the ones on my 64 & 65. I am not sure which part you are calling the "vacuum pod". I assume that is the "choke pull-off" shown in the photo, with yellowish plating. It's only job is to slightly open a fully-closed choke plate ~1/8". It can't keep the choke from opening fully because there is a long slot where it attaches.

The only thing that opens the choke fully is the bi-metallic thermostat which bolts in a well in the exhaust manifold and has a long rod going to the choke plate. It is not shown in the photos and I don't see where it attaches.

It sounds like all those parts are working correctly on your carburetor. If you want the choke to open faster, your thermostat needs an electric heater assist. On 74 slants in CA that was factory, but don't know about NV. If you post a photo of your choke thermostat, we could help more. If electric, there are other things that can go wrong, but the bi-metallic spring part would still work to eventually open it. Of course, the choke opening and the fast idle slowly dropping out go together (multiple steps on the fast idle cam).
 
When you're up to your azz in alligators, it's hard to remember you started out to drain the swamp!

In hopes of keeping it simple, is the vacuum tube to the pulloff kinked? it should run in a smooth arc from the base of the carb to the pulloff canister. Does the pulloff linkage from the vacuum canister to the choke lever operate smoothly, with no sticking or binding? Have ya tried using a long piece of the tubing (to get your face out of the carb) to simply suck the vacuum canister in and watch it release. A vacuum pump can be used, if you prefer.

some very interesting info is HERE: [ame]http://u225.torque.net/cars/SL6/docs/Holley_1945.pdf[/ame]

The choke vacuum part is about 3/4ths down the page.

Hope this helps.

ATB

BC
 
oh Bill! we're finally getting somewhere, I was using the wrong term...the choke pull off, that is whats messing up, it's not letting the choke open up like it should when it starts up COLD....my choke just stays completely closed and on the highest step of the cam until the thermostate starts pulling it open which is usually when I get out on the road and going fast.
 
64 ragtop, yep did all that...i've checked the vacuume lines over and over, all appears well..if the thing would ever get on the sencond step of the cam it would be open the 8th inch....but it just goes from being full force close and on to completely off when I get down the road.

ugh, i wish I could get a manual choke but i cant find one for my model...everybody keeps saying how the electric one is simple and shouldnt mess up but every problem I have when I ask around they tell me its my choke messing up so I don't get it....i think its just too complicated for me yet Ive had 3 mechanic mess around with it and none have them have set the choke or my idles/fuel mix as good as me....i'm in limbo :(
 
Great explanation. This should be easy to fix. If the pull-off doesn't work, the engine will run too rich until the bi-metal spring heats up and starts to open it. Worst-case, it can run so rich it "fouls" the spark plugs.

My experience with choke pull-offs:

In my 69 Dart slant w/ Holley 1920, the pull-off was bad for years. I didn't know what it was and thought it was a "damper" (that should leak). I was always fussing with the choke setting, having to set it loose in winter and weaker in summer. Had I only known, but there was no internet then and hard to get good info.

In my 65 Newport w/ Rochester 2 bbl, I think the pull-off went bad after a year. One day, it wouldn't fire at all and I ran down the battery. With a new battery, I first pulled the plugs and found them w/ light soot coating (i.e. "fouled", which shorts the tip to ground thru the carbon, bypassing the gap). I changed all plugs and it fired. That was a pain since living out of a motel with 1 car and 1 kid, as we just returned from overseas. I think it was then that I finally learned about the pull-off.

First, check that your diaphragm isn't torn. Easiest with a vacuum pump (~$20 on sale at HF). If not, remove the rubber hose, push the plunger in, cover the hole w/ your finger, let go of the plunger and see if it stays in. If not, the diaphragm is surely bad. If OK, move on to adjusting the linkage. You bend the long U to make the rod longer or shorter. If no vac pump, just hold the plunger in with your finger. The manual above should detail how much it should pull the choke plate open. They usually show holding a certain size drill bit in the gap. If all checks out, you should see the pull-off, pop the choke open to that gap as soon as the engine fires. If not, maybe your hose is connected to the wrong port on the carb. Does it look just like the generic photo you posted (bottom port, which should be "direct manifold vacuum")? The other port might be "timed vacuum" which should go to the distributor's vacuum advance canister. The 1945 manual should show. Your photo shows 2 hoses, but not which goes where.
 
I did all the early stuff you talked about, vacuum pod ok "check", bend u to 1/8th in' open on sencond step "check" hoses not cracked or worn "check"

nothing was changed as far as vacuum lines unless someone is messing with my car and I didn't know it so I'm at a lose, but the thing gives me more trouble than just this alone (stalling from choke coming off to soon an engine wasn't ready for it yet or coming on when it doesn't need to when starting and so on) so I'm just gonna swap it out for a manual choke....this choke has been the cause for many of my problems :p can't wait to get rid of it and do it myself.
 
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