Xavier777

sorry about all the questions but I have a list and I am trying to cross it off. Anyways my 64 f85 deluxe has trouble getting started. I know when the engine gets hot the choke opens. But my choke is how you see ing the picture before I start it and I have to fiddle with it to get it started. my question is, is it supposed to start off closed all the way because mine cannot, like there is something in the way. thanks for any help. sincerely, kevin.

z11375ss

If that motor is cold when you initially press the gas that sucker should close and open as you kick it down or give it gas or as it warms up. You need someone in your area to tune the choke. I did mine and the car starts with one press of the gas pedal and warms up at fast idle. It really works well. If you encounter something that is above your knowledge level you need to enlist the help of someone who knows what's up. It's hard to diagnose something over the internet.

rocketraider

With engine cold, try moving the choke plate thru its full travel- all the way closed thru all the way open- without setting the choke. If it moves freely you have an adjustment issue; if not, something is preventing it from moving.

When you set the choke on a cold engine (below about 50 degrees) the choke plate should close off completely. Once the engine starts and establishes vacuum, a vacuum passage applies vacuum to the linkage and opens the choke plate about 1/8" to give the engine enough air so it won't flood out. As the engine warms, hot air flows over the choke thermostat coil and relaxes its spring, allowing the choke plate to move to fully open.

On your Rochester 2GC carburetor, look at the round protrusion on the back side of the choke thermostat coil housing. There is a small piston in there that opens the choke as described above. My guess is either the internal vacuum port is stopped up or the piston itself is seized in its bore, preventing the choke from moving.

Also look at the choke coil itself. You will see a small mark on it that aligns to a series of notches (you may have to clean it off to see it), and <-RICH LEAN-> with arrows pointing in the corresponding direction. Correct choke setting is one notch in lean direction on these engines.

The set of 1964 Chassis Service Manuals will help you with this car since it sounds like you're not afraid to tinker a bit. You can probably find it online on wildaboutcars.com which has a lot of the factory manuals scanned in. In the 1964 Oldsmobile manuals, you need Vol 1 Section 4, pp 112 thru 123 which describes the 2GC carb for Series 30-31-32-33 (F85/Cutlass/Jetstar 88).

Don't worry about the questions. We're here to answer them and guide you right. You gotta remember most mechanics won't know as much about the choke as you do because they've been working on fuel-injected cars the last 20 years.

z11375ss

Yeah, that's exactly what I said. LOL! Great info, Rocket!

HonestDave

Hi Kevin, most of the old cars I've had start just fine with the choke closed 3/4 of the way (like yours is). In fact, I've had plenty that wouldn't start at all if it closed all the way. It seems to be a balance of getting it so it's happy to start, and still opens all the way when it's warm. It definitely has to open all the way at normal temperature. Many is the times I've even had to stick a screwdriver in the hole to keep it from closing all the way, as it would seem to choke it to much and the engine would die.
One thing I've found over the years, all the cars seem to be different for me. I could have two identical cars, and they might start and run totally different. I guess the wear and condition of various parts affects everything in their own way. Each old car seems to be a new adventure. I've got an electric choke on my 65 442 carb. You'd think I could get that set up. They're always easy. Not this one. Doesn't have enough travel. If I set it closed enough to start, it doesn't open all the way. My guys tell me these things always work, but guess what? I'm working on other cars right now, and by the time I get back to this one I'll probably have forgotten what was wrong. Luckily, the trouble will wait for me !!
Good luck.

oldcutlass

It should not be closed all the way, and yours seems to be adjusted correctly. If it is closed all the way it will not allow enough air in there to start. Does it set in the position shown in the pic with one full pump of the gas pedal? You might want to double check your tune settings.

MDchanic

I disagree - the choke should close all the way when cold, when the fast idle cam is released by pressing the pedal to the floor once.

As soon as the car starts, the vacuum pull-off will open the choke slightly, but if you look at it before it starts, if it's cold out, it should be closed.

From the 1964 Service Manual:



Of course, it could be that our ideas of "cold" are different. We need to know what the temperature was when that picture was taken.

- Eric

brown7373

With the choke closed all the way, as it was designed to do, it draws air through the idle circuits. They can get plugged and need to be soaked and cleaned out on a rebuild. When a carb isn't working as designed, there are ways to fiddle with it to get it to work. But when properly cleaned and rebuilt, you press the gas pedal once to set the choke (closed) and turn the key and it will start. If not, refer back to properly rebuilt and properly adjusted. Mine, although Q-jets and not 2 bbls, start the first time, every time whether sitting 24 hours or 24 days since the last start.

D. Yaros

Well, I have read this entire thread. It starts with the person asking a simple question. It seems that simple question should have a simple answer?

Obviously, all is not as it seems?

If I was a total neophyte, after reading the thread I would be far more confused than before asking my question.

I know what my answer to the question is, but will not offer it so as to not add to the confusion.

Instead I will ask a question. Can't we provide the questioner with a definitive answer to his simple question?

MDchanic

A simple answer, Dave, will require that we know the temperature of his carburetor at the time that the photo was taken (if the engine was cold, then ambient temperature would be fine), otherwise we have no idea how open it should be.

- Eric

z11375ss

x2

rocketraider

We did.

Eric hit on something some of us missed- AMBIENT air temperature. I too have seen and owned cars that started perfectly fine with the choke plate a little off fully closed, mostly with Holley carburetion. I've had several Holleys that started fine cold with the choke plate wired full open or completely removed. They also got abysmal gas mileage, but, nature of the beast.

Maybe we did get a little deep for a neophyte, but from the questions Kevin's asking, sounds like he's interested in how his F85 works. He's figured out that the choke may be the cause of his hard starting, which impresses me for a 15-year-old who has grown up in a fuel-injected world.

rocketraider

K, one more thing to think about- you'll see a metal tube running from the choke housing to the intake manifold. It connects to a U-shaped tube that is mounted in an exhaust crossover passage in the intake. The vacuum passage to the choke piston sucks outside air thru this tube where it's heated by exhaust gas, and as the heated air passes over the choke coil that's what signals the choke to open as the engine warms up.

I've seen those tubes in the intake burn thru and allow exhaust gas and soot to pass over the choke coil, which is TOO hot. Exhaust heat can seize up the choke piston and burn up the choke coil spring, which will cause a choke mechanism to seize up.

You can take the tube loose from the choke housing and pull it out of the intake (use penetrating oil on it, it's a slip fit but probably rusted together after almost 50 years). Start the engine and see if you hear any pfft-pfft noise coming thru the tube on the intake. If you do, the heat tube has a hole in it.

1964 CSM, Vol 1 section 3, p 138, figure 3-405 is your reference. Sorry I don't have a scanner to post it for you. Eric?

MDchanic

WildAboutCars, baby!

Start at page 4-16.

- Eric

Xavier777

Outside it was very cold so I will probably guess that in the garage it was probably 35-40 degrees

MDchanic

Should be closed until it starts to run.

- Eric

Greg Rogers

I really don't want to add to the confusion here but I think we all could help Xavier if we were there to put hands on the car and awful hard to do long distance! But I have looked pretty good at your picture on the 1st of this thread and I think the high idle cam is holding the choke from fully seating. If you look at the lever that comes down from the choke plate and goes to the fast idle cam it looks like the step of the cam is holding it from fully closing.(on the right side of the carb or the bottom of the picture) The adjustment screw is right at the step of the cam, which I think is just as it should be. If this pic was taken before the choke was "set" I think this is as it should be- The spring in the housing is cold and is pulling the plate closed as far as it can pulling the cam up against the screw. If the driver then "sets" the choke by pumping the accelerator pedal, the screw will be pulled away from the cam and the choke plate will fully close and the screw will go up on the cam causing fast idle. Then after car starts vacuum pulls on choke pull off and runs on fast idle until spring warms up allowing plate to come back towards open. Then driver again hits the accelerator pedal to go to normal idle. When car is cold (I'm guessing 40or less) get in car and pump gas pedal once then pull off air cleaner and see if plate is fully closed-it should be. These cars needed a pump or 3 (or more) to set the choke and to also squirt gas into the carb for cold starts. You can't start a carb car the way you do a Fuel injected one. Hope this helps- hope you're enjoying your 64!!

jaunty75

I know the feeling. I have trouble getting started most mornings.

z11375ss

This is an excellent diagnostic test. I did it on my Vette the way described and found the electric choke had become unhooked from the electric source. When I would pull the air cleaner the choke would be in the right place which would be open a fair amount. The problem was, that was where it was ALL the time. Therefore it didn't operate properly. Once these chokes work right they are Heaven on earth.

BILL DEMMER

ok, this is real simple...
the choke should be completely closed below 70 degrees F.
after the engine starts and is running, the choke should open to the specified vacuum break setting.

any other info saying the choke should be open any amount, on a cold engine that is not running, is purely and simply incorrect.


bill