Carb question

hitest1024 · #1 (**permalink**) 06-29-09, 10:22 PM

Hi-
I have a 68 Deville that I'm bringing back to life- it had been sitting for 5 years until 1 month ago. Hopefully this is a simple question for someone who knows carbs...
Basically the problem is this: To start the engine cold, I have to spray starter fluid into the air filter. Will crank forever but not catch if I don't, and starts immediately and perfectly with a single shot of starter fluid. From there it runs perfectly, idles well and will restart easily when its warmed up.

Also, I noticed that on the passenger side front of the carb, there is a triangle shaped lever that is just sitting there. It gives no resistance when pulled toward the passenger compartment, looks like its missing a spring?

Thanks for any advice.

steelybill · #2 (**permalink**) 06-29-09, 11:28 PM

That looks like part of your auto choke mechanism. My old book isn't too clear on that carb. That little cover that is (I think) mounted on the manifold next to the carb, has, or supposed to have, a climatic spring in it for the choke, and a rod going from there to the choke lever. Maybe a picture of that side of the carb with the air cleaner off would help get an idea of what you need.

That's a 472 engine, rated at 375 HP @ 4400. Optimistic figures !! It does have 10.5 to 1 compression, and likely needs good gas.

cadillac_al · #3 (**permalink**) 06-30-09, 09:01 AM

A good older mechanic could adjust that choke in less than 10 minutes. Finding a good older mechanic that won't overcharge for that simple job may be another matter. I'm not a fan of starting fluid; heard too many horror stories in the old days. I prefer to squirt gas in a carb if the choke isn't working.

hitest1024 · #4 (**permalink**) 06-30-09, 09:25 PM

OK- so today I went out and figured out that when I turned the lever in the picture toward the passenger compartment, it starts right up, even when its cold. And yep, steelybill- that lever seems to be controlled by whatever is down in the covered compartment in the manifold. Is that considered part of the carb? I'm going to take off those bolts and see what's under there, but I"m guessing I need to replace it.

And yep, finding a carb guy these days is getting harder and harder.

cadillac_al · #5 (**permalink**) 06-30-09, 09:55 PM

Does the spring move freely? is that linkage moving freely? When it's cold and you kick the accelerator the choke should close. When the car starts a vacuum plunger opens the choke about 1/4 inch. That's all there is to it. With a little fiddling it should run perfect in any temp.

steelybill · #6 (**permalink**) 06-30-09, 10:28 PM

That's called a "divorced choke" if I remember correctly, since the climatic spring is mounted on the exhaust cross-over under the carb. Those usually work very good, and are simple.

hitest1024 · #7 (**permalink**) 07-01-09, 09:16 PM

The triangle part (the one that allows it to start cold) moves pretty freely, but it is attached to whatever is coming out of that cover (the divorced choke?)
So stomping the accelerator should move all that mess when its cold and the key is in the 'on' position?

I'm guessing I need to just go in and put white lithium grease on everything and make sure it moves freely...

Thanks so much for everyone's help- its been great driving this around the last couple days.

steelybill · #8 (**permalink**) 07-01-09, 11:46 PM

The design is that when the pedal is pushed down a bit, the choke is closed by that climatic spring under that little cover, and the fast-idle cam moves also to keep the engine running during warm-up. The cam moves along with the choke as the engine heats the climatic spring , making the spring release tension on the choke lever.

cadillac_al · #9 (**permalink**) 07-02-09, 08:19 AM

You don't need the key on to check the choke operation. Just take off the air cleaner and move the throttle and the choke should close. It should actually snap shut with a little tension. If you turn the key it should start immediately and the vacuum choke pull off should open the choke about 1/4 inch. There are actually specific measurements for the choke opening but I usually eyeball it close enough. As it warms up the choke will keep opening until it is fully open. I wouldn't use lithium grease on the linkage; it might attract dirt. I usually use any old spray I can find; wd 40 or break away etc.

priests500 · #10 (**permalink**) 07-06-09, 12:44 PM

Ah, the divorced automatic choke. Been there with steelybill and drmenard on this issue before. They were a great help to me. Here is a link to one of those back-and-forths...

http://www.cadillacforums.com/forums...ced-choke.html (Qjet divorced choke)

I bring this up because I posted a pic of my choke. The stove on mine is a bit different (mine is a 71); however, the point of this is to show that the linkage is likely your problem. Your pic seems to show that the linkage is cut. I am guessing that is what you turned to the passenger side and got it to work.

I have found several of them like this. Sometime guys just give up getting them to work. All of the loose ones I have found are this way because it can be easily removed by cutting the linkage without disassembling the whole carb. Once I found guy who had cut his because the other part of the choke linkage often falls into the carb if it detaches.

awadecki · #11 (**permalink**) 07-13-09, 05:07 PM

Who would cut that?!

Yes, you'll need to restore the linkage in order for the choke to work properly. My guess is that someone cut it because the pull off (the round canister thing) wasn't working properly and it flooded the engine out. I can almost guarantte the pull off isn't working.

So, in summary, restore that linkage, and buy a new choke pull off to install on the carb. Then, see if depressing the accelerator when the engine is cold causes the choke butterfly to snap shut. When the car warms, it should begin to open.

Your car must run very rough right now when it first starts without a functioning choke. Probably dies when you put it in gear, too.