Allan R

That was my thought also. It should be on the front (drivers side) of the intake. There are so many raised and tapped bosses on these manifolds it could be easy to mistake, but the lift is uniform in design and can't be installed backwards.

EDIT: This picture shows the lift position very clearly.

brandon reynolds

tcolt

It looks like I was asking for it with all my previous silly questions, but here is proof that I mounted it in the only location on the manifold where it could go (maybe backwards?). Maybe I'm being a little picky, but I was just wondering if the bracket should be touching the intake runner and sort of scraping off the paint at the lower, inside edge of the rear hoop of the bracket. I'm probably a little too OCD for most people :-)....

tcolt

..and thanks a lot Brandon. Your product looks great and I definitely would be interested if I was going to restore my engine bay to more than a good driver standard. I got a bunch of my missing brackets from Scott (Oldspackrat) and the rest were reproductions from INT. I even found a nice (and cheap) aftermarket positive battery cable in red from East Penn that comes close enough to the original. I'll pass the part number along once I pick it up next week.

tcolt

Allan, I noticed you have two spark plug wire clips holding your wires on the drivers side. I only show one in the books. I like how tidy yours looks. It got me wondering if the "space" on the driver's side plastic clip is to make room for the oil dip stick tube. Like this: (obviously, the after market spark plug wire set in my car is too long....)

OLDSter Ralph

I am sorry, I didn't consider it a silly question. The pic you uploaded was sooooooo close, it was hard to tell where it was. You might bend it slightly to fit, your choice. Its only going to scrape paint if its a moving part, and its not. Paint it the engine color and forget it.

tcolt

No worries. I was only kidding. I think bending it is probably the answer. The question is whether the thick washers are still used on top of the bracket, same as with all the other manifold screws. I'm also still curious whether these parts were painted along with the engine, which seems likely. That would mean that when you removed the bracket and screws and washers there should be any blue of gold paint , but just cast iron?... I know we're getting in forensics here. I'm just curious...

OLDSter Ralph

You can spray or dab some engine paint on the manifold before putting the bracket back on. Yes, use the thick washers, see the pic Allan R posted. The washers help get the correct torque on the bolts.

Allan R

Tom, that picture I posted is just for reference. It's not my car but I use the same setup with the plug wires. Easier to manage them and the routing that way.

tcolt

This is crazy. I could have sworn that this thread had a discussion where Norm (Vintage Chief) posted some pictures to help me work on my vacuum hose routing and a few other things. Yet, I've searched up and down this thread or any other one in the last few months and I can't find them. In this thread there are a lot of references to his posts in this thread, but I can't find or see the original posts. This is weird?...

I've gotten much closer on why my engine won't run once it warms up and it has to do with the automatic (stove pipe) choke which, I think are known to be notoriously unreliable. My car won't even try to start when the choke plates aren't completely closed and the engine is cold and fires up and runs great at a fast idle once they're closed. Then, they won't open even after the engine warms up and it dies because it's not getting any air. The only way I can get it to run again is if I completely readjust the bi-metal spring in the choke. When I do that, it's out of adjustment for thee next time I start the cold engine. Can't I just temporarily disconnect the choke and should the engine only start with the choke completely closed?

Thanks, Tom

Vintage Chief

Hi Tom -
I removed my pictures because I believed they were evidently not providing any value to your thread (see Posts 74/75). I can re-post those pictures if you believe they would assist you. I may attempt to moderate my sarcasm - don't hold your breath.
The stove pipe choke network is not necessarily notoriously unreliable. I believe the stigma surrounds users who may not know how the system works & is adjusted for proper performance.
The first you thing you might/should do is remove the choke from the system to get the car running and at a basic starting point. I can easily walk you through the stove pipe setup and tuning sequence. I'm playing golf @ 8:00am, I'll try to establish a baseline for you until I return from golf later this afternoon.

Don't remove the choke stove pipe heating element in the intake manifold (I suspect it is in fact installed in the intake manifold), and if you have new stove pipe tubing installed into the intake manifold heating element don't remove those and leave them hooked up. Leave the vacuum tubing hooked up to the back of the air cleaner/breather from the stove pipe tubing choke inlet (this is your fresh air choke inlet which leads into the nipple of your choke housing). Leave the small vacuum line from the choke to the vacuum port on the carburetor, as well. All you need do is leave your lines hooked up & remove the choke cover plate - that is all. You will effectively have removed the choke functionality for all appreciable purposes. There will be no hot air supplied to the choke spring and you won't be employing any vacuum to the choke - albeit, no choke. The choke spring should (at this point) be ineffective. Your choke plate (top of carburetor) and choke linkage should move freely. With the engine cold, the choke plate should be ~1/8"-1/4" open - no more. The engine might idle high. Allow it to idle high for several minutes - you can 'kick down' the engine choke plate after several minutes using the accelerator pedal but the engine should be running fine outside of a high idle. This assumes the fast idle is setup correctly which it probably is and I'm going to stick w/ the basics of the choke stove pipe assembly working and not a complete carburetor setup at this point.

You should have already set your dwell (30*) and your timing (12*BTDC) @ 1100 RPM if you're using distributor contact points/condenser. Obviously, this must be done with all vacuum lines connected to their appropriate/respective ports.

You should ensure your vehicle has the correct vacuum - ~18" Hg to 20 "Hg. Using a vacuum gauge, measure your vacuum using a 'T' connector in-line w/ the ATM modulator or directly into the ATM intake manifold vacuum port. Adjust your LH & RH carburetor A/F needles to the maximum vacuum pressure you can achieve. Simply turn each one inwards or outwards until you achieve maximum vacuum. If you cannot achieve between 18" to 20" Hg vacuum pressure, you'll need to address any suspected vacuum lines and make those adjustments to your vacuum.

I'm hesitant to post my previous pictures at this point because they may provide more clutter than helpful advice with any narrative. So, let's start w/ your engine running. With the choke cover plate removed, your car should start and run fine - you just won't have a choke. The choke spring (which is heated via the stove pipe tubing assembly) will be inoperative - and the choke vacuum will be inoperative. You can of course, plug the stove pipe tubing line at the back of the carburetor but this won't have any effect since you're not pulling a vacuum on it at this point.

I have to head out to play golf. I'll post the pictures w/ narrative when I return this afternoon. Others might provide some additional details regarding the simple setup of getting your engine running w/o the choke at this point. TTYL

Allan R

Tom, the stove pipe you're referring to - is it the one that runs from the top of the right side exhaust manifold to the air cleaner? If it is, there is a theral switch located in the air cleaner base that connects it via rubber tubing to the air inlet on the air cleaner snorkel. Those 'thermac' units do tend to malfunction but the good news is they are reproduced. They're just not that light green color that AC Delco used for production. Here's a link: Air cleaner temp sensor

If you still need routing diagrams for the vacuum lines from the 72 Assembly Manual LMK and I can scan some and post hopefully what you're looking for.

tcolt

Ok. Thanks guys. I'm sorry Norm that I didn't respond more and show my appreciation for your posts. I found them all very interesting and helpful and was going to get to them all and complete this thread. Since I don't have that much to contribute with my knowledge of Oldsmobile cars I try to "give back" to this site by thinking of my threads as possible nice resources for somebody to refer to in the future who has similar problems. I hadn't even moved the car since February because I was focused on body and paint and I also have some health issues and the time I could put into the car was focused on painting and polishing and assembling the big body parts in my living room that could go back onto the car. Please don't be upset if I am not caught up with your instructions so far by the time you get back from golf. :-)

I will probably be able to disconnect the choke, but I'm not sure what will hold the choke 1/8" open without it connected to anything. When I had tried this yesterday the choke kept on "falling" open and wouldn't start. A friend of mine was even surprised that this was so critical and said he has had many cars where he hasn't had a choke at all and that most of these engines should start up in Southern California without much trouble anyway. NOT SO on this engine. I'd say 1/8" or completely closed works like a charm. After that, I don't know if I need to do anything to keep the choke open when the engine's warmed up....

Thanks, Tom

Allan R

tcolt

Oh, oh. I don't mind you guys trading jabs on my thread, but I hope you can still be adults and take it without forgetting the intent of what this site is about, which is to help each other out. (Yes, I know that on this site I am taking more than I am giving. On other's it's the other way around. Happy Easter!....

P.S. Allan, if you think a horses **** is the answer to my choke problems then you must have forgotten how narrow those choke vacuum tubes are...

tcolt

Ok. Before you guys get at it again, here is what I've done... It turns out that even after removing the bi-metal spring assembly, the choke plates are still not completely free, but are tied to a lever (that sits "behind" the "choke can") and I think, the idle speed step-up cam so that now the choke won't stay closed enough to get the engine started and will probably not open after it's warmed up just by "stabbing" the throttle as you would normally do to get the engine off of the high idle. It seems like maybe that lever binds a little and it interferes, both while trying to get the choke plates to stay closed when it's cold as well as opening after the engine has warmed up. Taking the air cleaner off every time to manually move that lever while jiggling the throttle lever is just not very practical...

Arrrgh! Tom

tcolt

It looks like the bi-metal spring is in charge of opening the choke plate as the engine warms up. Is this right? Then what causes the choke plate to close in order to get it to the cold start position? I think there is a thin-wire spring coiled around the shaft behind the choke can, but that one seems to not be working or it's jammed up somehow or maybe that "step-up" lever too? Am I barking up the right tree?

Tom

Vintage Chief

Ensure your vacuum lines are all attached as per the CSM.
Review this basic operation. It doesn't get much simpler.

I tune my choke the same manner as this gentlemen.

I cannot speak to whether you have all the correct parts on your carburetor. The throttle linkage itself controls the choke linkage.What is the model number of your Q-Jet carburetor.

tcolt

Thanks Norm

My carb is a Quadrajet # 7042250, which is correct for my 1972 350 engine and I rebuilt it carefully although I didn't touch any adjustments or bend any rods, etc., since it looked untouched/ undamaged and I thought that would be a good starting point. With your reminder to look at the CSM I went and found it (I would have never started to look into a CHASSIS assembly manual for information on how to adjust the choke on a carburetor, but thanks for pointing me in the right direction :-)...

Nonetheless, I ran into trouble with the directions on page 6C-5 of the 1972 CSM for the vacuum break adjustment where step two says: "seat diaphragm by applying at least 10" of vacuum". Since that vacuum isn't easy for me to produce without the engine running I figured that pulling the diaphragm in as far as it would go should mimic the "more than 10 in. of vacuum. That brings the vacuum brake rod (I figure that must be the horizontal rod that connects to the slotted lever for the upper valves plates on the secondary) as far as it will go in the slot on that lever. If you are still following me, does that sound right?...

Step 3 wants me to rotate the lever inside the choke coil cover counterclockwise until the "tang on the outside lever contacts the vacuum brake rod". I don't know where or what that "outside lever" or the "tang" is. At first, the only thing that looks like a tang to me is shown right in the center of this picture that I took of the choke can area on my Quadrajet, but I can't figure out how that makes sense and my second guess that the "tang" could be the slotted lever for the secondary upper valve plates. If that's correct my vacuum break gap is about half the 0.23" it should be, but I hesitate bending the horizontal (vacuum brake?) rod without being sure first...

I hope that someone can answer some of these questions, since I still don't have enough basic information on how this choke mechanism works. (I did really enjoy the link you posted to the period video, even if it doesn't help me to check the correct operarion of my setup. The Corvette video looks like it could be a different series/ year and I'm not sure it has a heated vacuum/ stove pipe). I think that it couldn't hurt for me to understand the entire function of the choke in all this, which is why I asked my previous questions and which weren't covered in the videos.

To put it into practical terms, my choke valve naturally wants to rotate to the open position with the coil spring inside the choke can removed, but the coil spring looks like it is also supposed to push the choke valve open in a clockwise direction as is warms up. Obviously, that can't make sense and there needs to be some force that wants to rotate the choke valve into the opposite closed (counter-clockwise) position first before the valve needs to be opened as the engine is warming up.

Thanks, Tom

Vintage Chief

Tom- Do not bend any of the linkage rods on your carburetor. That's more of a fine-tuning adjustment for someone well acquainted w/ carburetors/chokes. Leave them as is.
When I made reference to your CSM my reference was in relation to your vacuum hoses e.g. "Ensure your vacuum lines are all attached as per the CSM"
You need to get the engine to start & remain running first. Then, you can make your choke adjustment. Notice in all videos - the choke plate is in the closed position when the engine is cold (has not been running and is not at operating temperature). Good for rebuilding your carburetor, so it should be able to supply the required air & fuel in order to run and hopefully ensure you have a good vacuum.
I think you need to be able to start your engine and keep it running first before you move further onto making choke adjustments. So, leave the adjustments alone until you get the vehicle started & running.
Did you remove your air/fuel (A/F) needles to clean them and clean the bore holes where they are seated into at the base of the carburetor? A normal starting point should be about 3 1/2 to 4 turns outwards from their seated position. Never over tighten the needles when you run them inwards to seat them into the carburetor, but do run them into their seated positions just to get them slightly 'snug'. Then, back each one out about 3 1/2 turns to 4 turns. You should be able to see the accelerator linkage move freely. Gain some familiarity w/ how the accelerator linkage moves by actuating the accelerator linkage w/ your hand and noting the movements of the choke valve - see Fig 6M-81 4MC Choke System. On a cold engine the choke valve (plate) will be in the closed position in order to start the engine. Adjust your A/F mixture needles (probably outwards) until you are able to keep the engine running - in any state - fast idle, slow idle or any running position. You may need someone to assist you with operating the accelerator linkage. If not, be patient - very patient. It will take several adjustments to set the A/F mixture needles until you have the engine running and it remains running. Use your hand to move the accelerator linkage - whatever it takes at this point. It is going to be trial & error for a period until you can get the engine running and remain running. If your carburetor is supplying fuel, then it is most likely supplying air. You don't need a choke to supply either fuel or air to run an engine. You only need fuel & air. So, adjust your A/F mixture needles until you have the engine running. Of course, certain items are obviously required to ensure the engine runs - spark plugs, distributor, coil, plug wires hooked up correctly, fuel in the tank, etc. etc. For the time being and moving forward, do you have standard points contacts and condenser in your distributor or do you have a GM HEI distributor system?

EDIT: OK, my statement regarding you don't need a choke to supply either fuel or air to run an engine is perhaps not one of my better statements. You need a choke to more or less 'manifold' the butterflies for optimal carburetor performance. I'm kinda in a rush to (you guessed it) play golf. More when I return but there are certainly others who can jump in to get your engine running. Let's get your engine running and remain running then make some tuning adjustments.

tcolt

I'm sorry Allan. I didn't answer you and once again I used a term without really knowing what it meant. I thought people referred to the choke heater in the manifold as the stove, so I meant the vacuum pipes that connect it with the choke can, I guess, to heat up the spring inside so it can either wind up or unwind, depending on how this thing is supposed to work. I'm sorry for that mistake.

Nevertheless, it looks like I'm having trouble getting across that I have rebuilt the carburetor according to a manual, including cleaning and re-installing the A/F screws as they were. That's why the engine starts and runs fine when the choke is closed and has done so ever since I did my 4 barrel conversion 2 years ago. I'm sorry that I'm being a little more direct Norm, but some of what you are writing to help me sounds like you didn't see that part or I wasn't clear enough and then, of course I think the more or less general information on thermally operated chokes that you provided doesn't apply to me because I am having different issues. Please don't take that to mean that I don't appreciate the thought very much or that you should take it down. I see this thread as a discussion or debate to spark ideas and that requires hearing and understanding good ideas and ideas that are off track, as well as the questions themselves...

To repeat it, the trouble I have is that no matter how many times I "adjusted" the choke before I decided to look for this thread and post here again. I cannot get the engine to run for more than a few minutes in the "cold" configuration. Clearly, the "automatic" choke is not doing what it is supposed to and I find myself having to manually re-set the choke plates to the open position in order to get the engine to keep running after it has warmed up. I have been driving (limping) the car for close to a week this way, which has been quite difficult as you can imagine, especially since nothing on the carburetor is accessible without removing the air cleaner housing. I have gone through the process you and the videos have described many times and checked for binding and trying to get a better understanding of the system and what each lever, cam or other component does to figure out if anything could possibly be binding or otherwise causing the choke plate not to automatically open up as the engine warms....

I know that I sometimes write so much that even the most well-meaning people sometimes just skip right to the end, but I feel like all of it is usually needed to fully understand the condition and offer your much appreciated advice to the issues that I'm faced with. Unfortunately, they are not as simple as figuring out how to start and keep my engine running ;-)...

Regards, Tom

tcolt

Ok. I think I figured it out. Another member on this site who was afraid to help me on this thread over worries that he'd hurt other people's feelings if he had a different idea answered my question by email about what causes the choke plate to open. I'll get into more details once I've made sure I'm on the right track, but for now there's no need to debate choke adjustment procedures anymore :-)
I have to go and put more primer on my d-pillar before the weather turns too cold again...

Thanks to you all for now. Tom

Allan R

Tom,
I'm glad you got this worked out. Would you mind sharing the information for others to see? I would like to see how it compares to the Rochester Book I have. Sometimes backyard mechanics have a better way of describing fixes in terms that others can understand.

tcolt

Thanks for asking Allan. I got permission from the member who helped me, to copy his answer to this thread and it makes sense to me that I should let those who helped me here in on the solution.

Please all read the following only if you are interested in details. I think what I found out was pretty interesting and in the end I'm happy that I got to use the ole' gray matter a bit for something that I might not have found in a book or manual :-)... Hopefully it will also prevent someone else from making a similar mistake.

Today was day two of driving the car around on errands and breaking down twice again. I wouldn't say that I have the issues all worked out, but maybe 80%....

I'll start out with the answers I got in response to my questions in posts 90 through 97 (in red, but missing my replies in between). They were critical to help me understand how the choke functioned and why it didn't seem to do what it's supposed to:

You asked at one time: what opens the choke plate?

No one answered. The choke plate is opened by gravity... On the passenger side of the carb, just below the air cleaner mounting flange and behind the choke housing, there is an irregularly-shaped weight that opens the choke when hot air relaxes the choke spring.

To back up a bit, the choke coil closes the choke plate when the coil is cool. When the choke coil is hot, it relaxes and allows the weight to open the choke plate by gravity.
I've attached two pictures. One shows the open choke plate and the next shows the closed choke. Notice how the weight changes position. It drops when the choke plate is open. (Keep in mind that that the phrase above that the choke coil "relaxes" could be a little bit misleading. I would say that the choke coil spring relaxing is really more like giving-way to the force of gravity which acts on the choke plate in the opposite direction. The coil spring itself actually coils up tighter as it warms up, as detailed below. To me, coiling up is not necessarily relaxing, even if the choke plate itself "gives" ;-)





You should be able to freely lift the weight when the choke plate is open; the weight should instantly fall back when you let it go. If it does not, or if there is ANY feeling of stickiness to the movement, it will not open the choke properly when hot air relaxes the choke coil.Stickiness is the result of some deposit on the guiding surfaces of the weight (behind the choke coil). Usually a brief spray of carb cleaner in that area along with manual weight movement will free it up.I know that it is possible to assemble the choke such that the gravity weight is in a bind (I've done it). If that is the case, you just have to remove the choke housing and reassemble, making sure the weight is free on its shaft.Regarding the wear marks... You install and adjust the choke cover by placing it into the choke housing and turning it counter-clockwise until the witness mark (scribed line on the choke cover) aligns with the index (tallest raised mark in the middle of a number of raised marks) on the OD of the housing. As you rotate the choke cover, you should see the choke plate close. Now install the screws and the spring clips.Your choke action will be very close to correct if the other adjustments are unaltered.If it's still not correct, I can walk you through the other adjustments too--but you said you didn't change anything when you rebuilt. So unless the first owners messed it up, the other adjustments should still be OK.
Now that I knew that the choke coil spring doesn't actually open the choke plate as the engine warms up, as I might have thought. The choke plate apparently naturally "falls" open by itself. So, maybe I had to figure out instead what makes the choke close when the engine is cold. I looked closely at the levers inside the choke can and the wear mark on the choke spring to determine how it closes the choke, but it didn't seem to make sense with the way my choke was currently operating. I figured that I first needed to check which way the spring moves when it's warmed up so I pointed a hot air gun at it and the coil tightened up. The coil spring was actually turning the choke plate closed as it warmed up. Counter-clockwise (when viewed from the passenger side).

I took another look at the set-up and I was baffled when I re-confirmed that the coil spring didn't open the choke plate up as it warms, but it also doesn't need to open it because it already falls open by itself under the force of gravity. So, I thought maybe the coil spring should close the choke when the engine is cold? The only way I could see to get the spring to rotate the choke plate in the other direction was to lift it off the prongs inside the choke cover and flip the coil over so it would rotate in the opposite direction. That seemed like it could make sense and once I did this I could finally set the choke up and the engine started up from cold and as it warmed up the choke valve opened up! The choke spring was installed backwards and apparently I never checked it or maybe I installed it backwards myself.Now, the engine starts up and runs pretty well when it's cold. The choke opens as the engine warms up and I can even turn the engine off and on during the warm-up phase without much trouble. However, two or three times I broke down because the engine died shortly after it started and it refused to start up again. This was after it had warmed up and I let it sit for maybe about 1/2 hour. The choke plate appeared to be in a position that seemed right for a recently warm engine, but no fuel was visible in the carburetor no matter how I played with the fast idle cam or the accelerator pump or the choke plate. I almost suspected that there was no more gas in the tank even though I filled it up and hadn't driven more than 20 or 30 miles since I started taking the car on test drives. Needless to say, it was quite a pain to have to call friends to rescue me with gas and now I'm carrying a gas can and battery cable with me...I learned from Norm's video that the Rochester carb. needs the choke plate in the right position to initially even get any fuel. This is something that is a mystery to some of my hot rod friends who are under the impression that you don't need a choke at all most of the year in SoCal and you could still start and run an engine. I'm beginning to think that this might not be possible with the Quadrajet? Help! Again!... :-)