interesting response and a discouraging one

[Bill75]

Try here also http://www.docrebuild.com/dr-r-web/INDEXX.HTML

and punch up page 83.

 

[allcoupedup]

thanks Brian. i was under the assumption the choke was brought back to "open" (off) by the thermo spring heating up??

The spring is what closes it - that's why it snaps close without the engine running. As the heated air is pulled through the spring, it unwinds and becomes very weak allowing the vacuum to hold the choke open.


When the choke is on the lean setting and the car has warmed up, can you you close your choke easily? If the vacuum pull-off is working, you should feel some resistance and the choke butterfly should feel like it is locked in place.

As far as pulling the carb I say GO FOR IT. Yes, it will be intmidating at first but you will see how the carburetor is a system of sub-components and you will see how they are all related. Yes, it is frustraing to pay someone to do something and then have to do it again yourself. There is no better way to learn car stuff than by tinkering with things and seeing how they work.
Brian

 

[Greg Gore]

It may Not Be All His Fault

The choke problem may not be related to your carburetor rebuilder's work. Your rebuilder was probably concerned about installing correct parts and gaskets to maintain originality and possibily recoloring the parts to restore its appearance. A rebuilder must make some assumptions about the owner's skills when accepting a carburetor for rebuilding when he does not have access to the car after it is reinstalled. All carburetors must be adjusted on the engine in order to get it to perform properly. It must also have a heat source up through the tube from the exhaust manifold to heat the bi-metallic spring which causes it to gradually back the choke off. Ideally this is syncronized with the engine warming up as less choke is required to keep it running. The fast idle cam has steps which also help keep it running in conjunction with the degree of required choke opening. It is usually necessary to do a cold start and adjust the choke and fast idle cam while the engine is running. I do not have your carburetor model here to look at but many of them have a link with an angle in it that connects to the fast idle cam and the degree of angle is an adjustment (bend to adjust) for staging the various steps of the cam. A fast idle screw is another adjustment. Is the leak coming from the fuel inlet fitting? It is usually necessary to use two wrenches to install and tighten the fuel line nut. Please let us know what is leaking.

Regards, Greg

 

[RodsnRides]

I have to agree with Greg Gore-it may not be "fault" of the rebuilder. The old "automatic chokes" drive most technicians nuts-myself included. Everything has to be just right. I have worked on Holleys, know Q-jets better, but the bottom line is all these moving parts, which are not lubricated, develop wear points, flat spots and, after multiple "technician" adjustments the linkages take on their own, non-factory, thus non-correct, shape. And, the rebuilder may have used an older-style "correct" bowl gasket, rather than the modern blue ones. Highly suggest getting the modern ones.

Removal of your exhaust spacer will also affect your choke operation. And, of course, those thermal springs DO lose their "elasticity" over time.

Barry, may I suggest you get yourself a fresh spring and cover per John Z beer), and make sure your heat riser tube is working, and check for a good seal at the housing. The earlier point about that seal is valid. The little choke piston thingy, if that Holley has one, is important-look for wear/looseness.

Good luck, hang in there, and realize that patience is good-and look how much you have picked up regarding vehicle maintenance and repair in just the last 6 months! How much do you suppose you have saved?

Rick

 

[BarryK]

greg, the choke tube is there!

 

[BarryK]

Bill, thanks, I will check to see if Doc Rebuild has the part also

Brian, ok, i get it, the spring closes it and the vacuum opens it up again.
yes, as the car warms up and is up to temp, if i attemp to manually operate the choke valve i do feel resistence. I thought that was strange because previously before the rebuild it actually moved real easily

greg, I'm not as upset by the problem with the carb as much as i am with his attitude of OH WELL....... I don't know and i don't care which was the impression I recieved from him. I do understand that adjustemt cannot all be made on the bench but after attempting the proper adjustments it's obvious that something is wrong. The fast idle cam is not dropping down the last step to tuen the choke completetly off. The fuel leak isn't coming from the fuel intake, it's coming out from under the rear fuel bowl.

Rick, yep, the choke tube is there and it works...in fact just burnt myself slightly on it a little bit ago as i was trying to work on the choke.
the spring is the first thing I'm going to try and will be on the phone tomorrow to try and dig one up

thanks all

 

[JohnZ]

To clarify - the vacuum piston connected to the choke (the "choke unloader") pulls the choke blade back a little (creates a 3/16" gap from the lower edge of the choke blade to the air horn opening) the instant the engine starts so it gets enough air to idle while the spring is still cold and coiled tight, tending to hold the choke blade closed. As the bi-metallic coil heats up (hot air from the exhaust manifold, through the heat tube), it unwinds and holds the choke blade fully open.

 

[BarryK]

thanks John, it definitely seems to sound like that problem is in the spring than and it's not pulling back with enough tension to drop the fast idle cam down all the way.

i'll be on the phone in the morning to try and get that housing assembly and spring unit.

 

[Greg Gore]

More Choke Stuff (and a little about the leak)

John's post about the choke unloader is helping me think about this. I don't have a carburetor like yours here to look at so will need to rely on info as it comes in. The choke unloader is a piston in a bore inside the choke housing, behind the bi-metallic spring. It gets a vacuum signal when the engine starts and physically pulls the choke blade open a predetermined amount to keep the engine running. This should be adjustable and will be critical to the running quality after a cold start. It would be important to know the unloader piston is not binding in the bore or does not have excessive wear resulting in improper choke unloader operation but your rebuilded probably checked that. When the engine is cold (engine not running) does the choke blade close with the cap set at the specified setting (1 lean)? You may have to open the throttle a little to release the fast idle cam to set the choke but it should snap shut. If not, then your bi-metallic spring is probably faulty. The adjustments can be somewhat critical because they are related and dependant on each other and designed to work together. The heat riser valve being missing will also contribute to making it difficult to get working again properly. The reason why is it takes heat to atomize fuel; nothing else will do it and you cannot burn liquid fuel. Heat risers are installed by the factory to warm up the intake manifold quickly after a cold start so the fuel can atomize quicker. Folks often remove them and never experience a problem with it missing but the factory did originally put it there for a reason. Fact is if you are trying to duplicate original factory driveability and adjust all the settings back to original specs you may need to reinstall it. The fuel leak may be due to leaking soft plugs underneath the bowl. If your carb has the plugs you might swedge them a little or remove them to epoxy them back in.

Greg

 

[allcoupedup]

To clarify - the vacuum piston connected to the choke (the "choke unloader") pulls the choke blade back a little (creates a 3/16" gap from the lower edge of the choke blade to the air horn opening) the instant the engine starts so it gets enough air to idle while the spring is still cold and coiled tight, tending to hold the choke blade closed. As the bi-metallic coil heats up (hot air from the exhaust manifold, through the heat tube), it unwinds and holds the choke blade fully open.

Thanks for the clarification! 'Round these parts you learn something new every day.
Brian

 

[jims427400]

Barry,
I got to tell you, I'm not going to recommend Craig to anyone else.I'm missing a couple of pieces off my carbs(filter hold down bolt and base hold down bolt) I explained this to Craig and he said that he does'nt take them apart,his girls do that.And that they would have have been put back in the box.I knew I should have saved that box.Anyway that was all he had to say,I thought he could have at least said "let me check my bench"but no..
Problem here in Toledo,the weathers been sucky and I havent been able to drive the car and test my carbs to really tell you how Craig really did.
WISH ME LUCK !!

 

[IH2LOSE]

Barry

As always sorry for your troubles,if the carb is leaking send it back, no questions ask. As soon as you tear into it the leaks will now be your problem.

Was this guy just a replater or did he rebuild it also

 

[BarryK]

guys, sorry i didn't get back to you last night. I just finally had enough of it for one day and needed to stop, step back from the problem, and call it a day. Now I can start fresh again with a new perspective.

1. unless I completely misunderstand the reason behind it, I don't think the heat riser valve that has been mentioned a number of times has anything to do with this choke issue. My understanding of the heat riser is to warm up the intake floor on a cold motor to prevent plate out of the raw fuel entering the intake from the carb. With the heat riser removed as it is now, I suppose I may get some raw fuel pooling up in the bottom of the intake while the intake is still cold but I don't see how this affects the physical operation of the movement of the choke mechanism itself. Again, unless i completely misunderstand, i don't feel this is the cause of the problem. Plus, the choke issue initially started before the heat riser had been removed.

2. I can see the choke tube being a possible issue. I cleaned it as part of my clean up project but that was just the outside so there is a possibility something is clogging the tube itself which I'll check but I can say that it heats up very quickly once the car is started bit since it is inserted into the exhaust manifold at the one end it's possible it's getting hot not from warm air flowing thru it but as radiant heat from physical contact itself. I'll double check this. EDIT: i just removed the choke tube, checked it, used a stiff piece of wire to ream it out completely to be sure, blew thru it, and it's free of any obstructions and air blows thru it easily so that wasn't and isn't the issue. The choke IS getting the airflow from the choke tube

the issue seems to ME, but i'm just trying to learn and understand the whole operation and mechanics of the carb and choke, that it's purely a mechanical operation issue. Once warmed up I should be able to "tap" the gas pedal so the choke clicks off and the car returns to a normal idle spped but what's happening is that something is not allowing the fast idle cam to drop off the last step so the car returns to normal idle. I can use my finger and push the fast idle cam down to click the choke operation off but it won't do it itself by tapping the gas as it's suppose to.
Again, unless i misunderstand, as the thermo spring causes the choke to initally snap shut on a cold motor than as it warms up by the car running it "expands" (for lack of a better term) causing the choke valve to open up and after warmed up a final "tap" on the gas pedal should click the choke back into "OFF".
The problem is that a tap on the gas pedal is NOT clicking the choke into "OFF".
All tis leads me to believe that the issue is the spring as gone bad after 40 years and it doesn't have enough tension left in it to click the choke into OFF that last step OR something else that I can't seem to physically see or have missed seeing so far is binding up just enough to not allow the fast idle cam to click the choke into OFF position iself without my pushing down on it.

I'm not quite sure where this leaves me today on the problem, but this is how i see things this morning.

 

[BarryK]

Barry

As always sorry for your troubles,if the carb is leaking send it back, no questions ask. As soon as you tear into it the leaks will now be your problem.

Was this guy just a replater or did he rebuild it also

Larry, the guy is suppose to be one of the best rebuilders out there and he came very highly recommended by a very well respected member of this and other forums plus his name is constantly on the list of two or three people that i've seen recommended as i did searches for recommended carb rebuilders over on the NCRS board. He wasn't just "some guy out of the blue".

Now, I wasn't there looking over his shoulder of course watching to verify what he did to my carb but it was suppose to be completely rebuilt as good as new besides the replating. The replating service was just suppose to be an additonal service i requested as part of the job.

I know once I take the carb apart it's going to be my problem and not his, but after waiting six weeks for the carb to come back and than it comes back with one problem I mentioned not fixed and another problem that wasn't there initially i'm not inclined to send it out to him again, have to pay for the shipping again to send it out, and having to wait for it to come back again.

at this point i feel that except for the replating, I probably could have bought a book, bought a rebuild kit for the carb, and have done the carb myself so if i need to do that to replace the gaskets than that's what i'll have to do. I need to get the car running again, properly and without leaks, within the next couple of weeks so that I can get the car back over to the paint shop before the weather starts to get warm in the spring. If I delay too long my painter will start to get too busy again and as we all know he isn't the quickest guy around!
I guess it's time I learned how to do at least basic service and rebuilding on the carb anyway.
If push comes to shove, I may just give up, follow many peoples advice and give up on this carb and put a Barry Grant unit on the car. i'm trying to keep the car as stock as possible but since the carb really isn't seen under the air cleaner i've heard a lot of good things about the BG units. I'm not ready to give up on this carb yet though.

 

[Greg Gore]

Reid Vapor Pressure

I agree the heat riser is not directly connected to your choke and is not the main contributor to your current cold start issue but indirectly it will affect driveability during the warm-up period. The purpose of the heat riser is to get heat in the intake manifold as soon as possible to assist fuel atomization. As I mentioned before only atomized fuel can burn. The fuel atomizes by absorbing heat from the air in the intake manifold plenum and runners. In the winter time or in cold climate conditions heat for atomization is very limited. This is why the fuel companies adjust their fuel's Reid vapor pressure number seasonally. In the winter time fuel has more aromatics blended in such as benzene which lowers the Reid vapor pressure causing faster vaporization in lower heat conditions aiding winter startup and cold running performance. In the summertime this would be unwanted because it would vapor-lock easily so fuels are adjusted for higher Reid vapor pressure in warmer climate conditions. In the case of your missing heat riser and after your choke problem is corrected it is possible the choke would be unwinding while the manifold is still too cold causing balky performance or lean backfires. This is all engineering rhetoric of course invented by the guys with the white lab coats and you might not have experienced any of this so disregard as necessary. Back to your carburetor rebuilder: I am concerned he does not do the actual disassembly but rather he has a couple of girls doing it. I would prefer the person doing the rebuilding also do the teardown and personally keep track of all of my original parts. I am also concerned your fuel leak could be because you did not get all of your original parts back, perhaps the main body. The main problem with rebuilt components is that an assembly can be a collection of individual parts from 50 different carburetors.

Regards, Greg

 

[BarryK]

Greg
if he put parts on my carb form others than there not much for me to do about it now. i have to work with what i have sitting in front of me......
either way i'll not be sending a carb out again, i'll do my own in the future.

 

[BarryK]

update

I pulled the choke housing and spring off again, put it in water on the stove and as the water heated up i could watch the spring expand. once it stopped i dropped it into cold water and the spring instantly reverted back to it's original position so this seems to rule out the spring.

while the housing is off I played around some more. with the choke piston lever off the spring i can move the choke valve very easily of course so i can tell nothing is binding that up.
The only other area i can determine that could be the problem is the fast idle cam itself - which is exactly the part that isn't dropping down enough to alow the choke to go into the OFF position.

can someone tell me how movement on the fast idle cam is suppose to feel? I can move the cam with my finger but it's not real easy. is it suppose to move easily, or have resistence on it, or what? how or where exactly does the fast idle cam get it's movement from so i can check proper operation on that piece. THANKS!!

 

[Ken Anderson]

Did you pay this wizard with a credit card? If so, do a charge back and let's see if he has an attitude adjustment. Any half way competent rebuilder would have sent you a carb with not only a working choke, but it would have been tested and set up to go. Pay for shipping back! NO way, ask for a call tag. Leaks, even a rebuilt carb from Pep Boys would have been leak tested! Share his name with us, if he doesn't make it right The power of advertising is satisfied customers, not, oh well, TS.

 

[Greg Gore]

You might have discovered the source of your trouble. The fast idle cam must be free to move without resistance. It should move freely and in conjunction with the choke when you open and close the choke by hand. If it is stuck or binding someone bent something or damaged the pivot somehow possibly while it was being rebuilt. Let's try to get to the bottom of this and if it turns out your rebuilder is responsible I would be in favor of getting this posted to his reputation so other owners can know and be forewarned about him.

Greg

 

[BarryK]

Greg
I did more testing just now.
as it sits, the fast idle cam doesn't move easily, but with the throttle linkage help partly open, the fast idle cam WILL move freely.
sorry, because i'm just trying to learn all this, sometimes i don't know the proper way to test a part correctly. it moves freely with the throttle partly open but not with the throttle closed. i'm guessing that's normal??

my goal he is not to find "blame" or "fault". all i want is to get this thing working properly. Blaming someone and ripping apart thier reputation won't help me get this working. Yes, I was very upset with him yesterday and wrote part of my initial post from emotion and vented, but all i really want to is get this fixxed right so it works