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Joe & others may know the exact answer to your question regarding thermostat fitment for what years, etc. Yet, this is why it is good to provide us with...you guessed it...the MODEL # of the carburetor.
Thanks. I'll post The model number of this evening after I get off work and get to the car...
Again, I appreciate everyone's input and help as I am a bit new to this engine and carb setup
Unfortunately, the 68-69 choke coils are not readily available. Since these were also used on 442s, NOS ones go for stupid money (despite the fact that they were used on every 4bbl engine made that year). The correct part number for 1968 is 7028093. For 1969 it is 7029093. I would suggest that before spending money on a replacement, figure out why the original isn't working. It's just a bimetallic spring with a rod. There isn't a lot of science in it. By the way, the factory Chassis Service Manual tells you how to adjust that rod if necessary.
And yes, the choke exists solely to allow you to start the car when the engine is cold, so a choke that's wedged open will make a cold car difficult to start.
You'd be hard-pressed to find a guy w/ as much knowledge as Joe on these Oldsmobile beasts. Follow his advice.
Regarding the CSM (Chassis Service Manual). It is a MUST HAVE for your vehicle. It explains how all the devices on your vehicle operate, how to remove them, install them, tune-up, etc., etc. etc. It "is" the bible for your car...buy it ASAP. I'll provide you w/ a URL link to one. Do some research, you may find various qualities, various pricing, free shipping etc. Buy a used original OEM GM 1969 Chassis Service Manual....Good Luck!
I'm guessing the wet spot indicates that the carb is leaking, either from debris in the inlet needle or a plastic float that's been saturated with ethanol. What's that green wire under the bolt holding the choke? It isn't factory.
It's most certainly a ground wire. Just need to trace it so you know for a fact what it's role is. Additionally, that bolt is rather corroded and most likely not providing the BEST ground possible. If you intend to continue to use it (there are other options for a ground wire mount location), remove that bolt and wire brush &/or sand the mount, the bolt and the wire terminal end. As Jesse indicated earlier in this thread, that wire "crimp" needs to be enclosed in heat shrink insulation.
The orange lever affects idle. Does not seem like it moves smoothly or correctly.
Trying to figure out if there is something that is broken on this side but unfortunately I am not promoted enough to do to know
The orange lever affects idle. Does not seem like it moves smoothly or correctly.
Trying to figure out if there is something that is broken on this side but unfortunately I am not promoted enough to do to know
Download this manual (.pdf form). There are manuals which supersede this manual; but, they provide no different information regarding your Rochester Quadrajet carburetor & this manual is crisp/clean. You have a divorced choke Rochester 4MV carburetor. Note the diagrams illustrating the choke operations of the 4MV.
With the engine off try holding the throttle open partially whilst moving the high idle cam to see if it then moves freely.
Does the choke valve/blade move freely?
The .pdf Norm provided didn't work for me, but I'm browsing with my Droid.
You mentioned that the choke doesn't close all the way. You can adjust it. Instructions are in the FSM/CSM as others mentioned. There would also be instructions in a carburetor rebuild kit (if you bought one from the providers mentioned above or even your local auto parts store).
Last edited by Olds64; December 1st, 2023 at 08:03 AM.
Unfortunately, the 68-69 choke coils are not readily available.
Joe,
Do you know if the thermostatic coil itself is close enough in size to the later integrated choke assemblies so one of those could be integrated into the original divorced choke assembly? Just a random thought.
The coil seems to have pushed up the lever therefore allowing the secondaries to be able to be opened, I think
Now that the bolt is removed did the choke plate close on the top of the carburetor (air horn)? Is the choke linkage and fast idle cam moving freely? Vacuum hose shortened, no longer pinched?
If all of the above has taken place have you tried to start the engine?
I shortened the vacuum hose. The diaphragm seems to work as the plunger does get pulled into the diaphragm.
After removing the bolt jammed in there the choke does not move freely and doesn't close unless I open the throttle..
The fast idle cam moves freely when the throttle is opened. To me it seems like the choke needs adjustment. I downloaded the instructions but was a little confused so haven't tried yet.
The car did not start cold last night but the choke was open even after removing the bolt the PO had jammed in next to the fast idle cam.
Once it starts with starting fluid, it runs great, seems to idle well, and has good power.
It did seem the thermostatic coil was working as the secondaries were allowed to open.
I think I need to figure out the choke adjustment procedure. I assume that should be done with the engine cold...
With the throttle partly open, whilst moving the link that attached to the choke thermostat, can you close the choke blade completely?
Choke blade and fast idle cam not moving until the throttle is open is correct.
The choke blade should be completely open and the high idle cam on its lowest step for the secondaries to open.
Look for a small pin in the right side of the secondary throttle shaft where it exits the throttle plates and look for a pendulum like arm in the choke linkage that engages that pin when the choke blade is closed. Confirm that the pendulum like arm moves freely.
Joe,
Do you know if the thermostatic coil itself is close enough in size to the later integrated choke assemblies so one of those could be integrated into the original divorced choke assembly? Just a random thought.
If you're talking about the aftermarket electric chokes for divorced setups, the only ones I've seen for GM are for the Chevy divorced choke, which has a different footprint on the manifold. If you are asking about converting a divorced choke carb to a hot air choke housing so you can easily use an electric choke, that's on my to do list. I THINK it should be possible, but I haven't gotten around to trying it yet.
I downloaded the instructions but was a little confused so haven't tried yet.
Where did you download this from? The factory Chassis Service Manual is the place you should be getting that information. If there is any binding in the choke linkage at all, this needs to be corrected. And let's be honest, that carb needs to be rebuilt.
Agreed it should be rebuilt.
So got to the car today and after watching an old factory video about the correct way to start this car with the Rochester, I made sure the thermostatic coil was connected, which is wasn't when I bought it, and pushed the throttle to the floor, which closed the choke,and it fired right up
It idled high until it started to warm up and the choke fully opened and allowed the secondaries to open.
From what I can tell this unit functions very well. Im sure needs to be tuned and have a rebuild done, but otherwise there doesn't seem to be anything else wrong with it.
Maybe the PO wanted to start it up and mash the gas pedal before the engine warmed up or something?
Agreed it should be rebuilt.
So got to the car today and after watching an old factory video about the correct way to start this car with the Rochester, I made sure the thermostatic coil was connected, which is wasn't when I bought it, and pushed the throttle to the floor, which closed the choke,and it fired right up
It idled high until it started to warm up and the choke fully opened and allowed the secondaries to open.
From what I can tell this unit functions very well. Im sure needs to be tuned and have a rebuild done, but otherwise there doesn't seem to be anything else wrong with it.
Maybe the PO wanted to start it up and mash the gas pedal before the engine warmed up or something?
This is awesome! We know the PO jammed the choke open. Why? With a cold engine you depress the accelerator pedal about a third of the way to close the choke and set the fast idle. The engine starts and runs at fast idle. At the same that white vacuum chamber pulls the choke open about 3/8 to 1/2 inch. This is function is called choke pull off. From what you reported the engine runs satisfactory. Did you allow the engine to warm up to operating temperature? If not please do. Then look at the choke blade. Is it fully open?
If you're talking about the aftermarket electric chokes for divorced setups, the only ones I've seen for GM are for the Chevy divorced choke, which has a different footprint on the manifold. If you are asking about converting a divorced choke carb to a hot air choke housing so you can easily use an electric choke, that's on my to do list. I THINK it should be possible, but I haven't gotten around to trying it yet.
Actually I was meaning just the thermostatic coil itself.
I know the integrated choke coil will come right off the center post, and I was wondering if perhaps one could be made to work in the divorced choke assembly. This is assuming the coil dimensions are close enough and the divorced choke can be modified.
Actually I was meaning just the thermostatic coil itself.
I know the integrated choke coil will come right off the center post, and I was wondering if perhaps one could be made to work in the divorced choke assembly. This is assuming the coil dimensions are close enough and the divorced choke can be modified.
Got it. Unfortunately the coil is different. For that matter, there are dozens of different coils for the integral choke as well. The thickness and number of turns effect the rate that the choke opens as it heats up.
Thanks for everyone's help. I'll be getting this unit rebuilt soon as well.
This is a great reference and great people out there willing to help.
I'm sure I'll be reaching out for more soon!
And, we certainly cannot see/witness linkage movement for freedom, tightness, etc. and we can't visualize inside the carburetor and many other areas i.e. A/F mixture screws, etc. Carburetor maintenance (often overlooked by MANY) should/can be a minimum of liberal spraying w/ Carburetor Cleaner each year. You'll be surprised how well it can bring life into select areas which accumulate, grease, oil, dust, grime, sludge. Regarding a rebuild. If the carburetor is performing well, there are two ways to consider the term rebuild. I'm not convinced you need/require a complete rebuild i.e. new primary/secondary metering rods, plating, etc. Installing a correct helicoil for the fuel insert would be a plus. Rebuild "kits" are available for Rochester Quadrajet carburetors. Many vendors and I think someone already mentioned several places. With that said, you can rebuild the carburetor yourself if you choose to get more involved. It's actually quite simple and they cost anywhere between $40-$80 depending on what's included. Here's a URL link. Have fun, good motoring!
Almost forgot - purchase an original used OEM Chassis Service Manual (CSM).
ANOTHER AILMENT THAT MAY BE ADDRESSED WITH THE Q-JET, is the thrrottle shaft. the base gets worn and the shaft wobbles. they make" kits" to drill the base and install bronze bushings. I had to do that. not a hard job at all.
November 30th, 2023, 12:38 PM
