440-3 Carb Choke issue

WyzrdX · July 26, 2015, 10:52 PM

Hello all. I have just joined the site and have already found lots of information very useful. I am loving it.
I just bought a 1974 Winnebago Indian D25. I am going to make some changes to the floorplan as this is our new home, and update the systems. But first I must deal with the engine.

Which brings me to the reason I am posting. I have a few issue I need some advice on.

There is a choke issue and the previous owner who isn't very mechanical said after it runs a bit, when it stops and is restarted, you have to choke it by removing the cover and doing it manually. Would I be better off having the carb rebuilt or just add a manual choke cable? I have rebuilt engines but never a carb.

I tried finding answers but haven't been able to. Thanks for any help.

Oz · July 26, 2015, 11:27 PM

Is there a choke cable at all?

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WyzrdX · July 27, 2015, 12:02 AM

Thanks for the info. And I will post new topics as I get to them.

As for the choke, there is no cable I have seen.

Dr. Righteous · July 27, 2015, 01:37 PM

If the engine is a 440; MOST LIKELY it is equipped with a Carter ThermoQuad carb.
DON'T let anyone lead you astray concerning this carb; it is one of the best ever made.
I have been rebuilding these for decades. The only one I was asked to repair that I couldn't make work was a pitiful example of a TQ that a buddy purchased at a swap meet. He brought it to me because all it did was pour gas all over the place. I removed the top lid to find most of the internals were missing. D:oH!

The first question is if it seems to run fine when warmed up likely the carb is in good shape and it is just something wrong with the choke.
Make sure the choke flap operates to fully closed and fully open.
The Choke on these is bolted to the intake manifold and operates off crossover exhaust heat. So really the crossover system has to be working correctly for the choke to correctly work.
All parts are still available for these.

http://www.carburetion.com/choke.asp

WyzrdX · July 27, 2015, 03:07 PM

The choke flap moves well but I have to manually choke it to start the engine. I cant find any cables like what used to be on my Holly.

When I hold it closed it starts and then swings back open when I let it go. Could this be just a dirty carb? There is oil and grime on the engine.

Rickf1985 · July 27, 2015, 05:41 PM

There is a bimetal spring in a housing that bolts to the intake directly under the choke and there is supposed to be a rod from the choke to this spring. The spring is adjustable but I have seldom seen them in condition to adjust after many years of rust.

DaveVA78Chieftain · July 27, 2015, 06:49 PM

Daves Thermoquad Collection

WyzrdX · July 28, 2015, 12:53 AM

OK it looks like the images of the Thermoquad.

Everything is intact. It seems the problem would be just age. It moves freely but after a bit of time it will stay wide open. And when it is restarted after it has heated up, that is when it sticks open. It will stay open and needs to be given a manual push in order to close. And that is the only way to start it after it has been running a while.

Dave, One thing I did notice per the service manual is I cant find a vacuum line attached. I may have missed it but I am looking at a very dirty engine so its very possible.

I just drove it home and one problem I noticed is having to keep my foot on the peddle in order to prevent it from dying while braking.

So it looks like I will need to rebuild it. (or have someone rebuild it to ensure I don't goof it up.)

Rickf1985 · July 28, 2015, 06:59 AM

Once it is warmed up the choke is not needed to restart, if anything at all a half pump of the gas pedal before you start it will do the trick. Unlike fuel injection you sometimes have to pump a bit of gas in first before you crank it but you do not want to pump it too much or you will flood it. Really it should start right up when it is warmed up with just a touch of the gas at the most. Have you tried pumping the gas pedal?

legomybago · July 28, 2015, 10:07 AM

Sounds like your idle circuit is all crapped up! It's wanting fuel or a richer mixture to start at warm up (hence you closing the choke to make it start). Sounds like the choke is doing it's job staying open when warm. You never mentioned how long this baby sat before you purchased, so Im guessing a while. Pull the carb and rebuild.

WyzrdX · July 28, 2015, 10:33 AM

Rickf1985 yes I have pumped the gas. My first auto was a 1973 Chevy 454 w/ a holly carb. Almost always had to pump it.

legomybago AFAIK it sat for 5 years prior to the person I bought it from. He bought it to live at his mothers house. He drove it there and parked it again for another 3 years til he bought a house. So at least 8 years to my knowledge.

So it looks like a rebuild it is. Thanks for all the help.

Rickf1985 · July 28, 2015, 12:41 PM

Wasn't trying to be a smarty pants, just that a lot of people have never driven a carbureted car nowadays. They are used to turning the key and the engine starts with no input from the foot at all.

WyzrdX · July 28, 2015, 01:27 PM

I didn't think you were trying to be, I was typing in a hurry if I sounded that way. I understand. My wife is one of them. She has never had a vehicle that did have Fuel Injection.

I am worried how gummy the fuel that was in it was. I drove it to the RV place about an hour ago to see about getting the roof sealed. When I got there, for the first time, it didn't die when I let off the gas. It just sat there and purred. Still can let my foot off the gas when I break but its a start.

After the roof is sealed, I can get the engine and carb worked on.

Rickf1985 · July 28, 2015, 06:24 PM

You have to be careful with old fuel like that because it can cause the valve stems to gum up and stick bending pushrods if you are lucky or breaking a cam if you are not. I would get that stuff out of there and get a good load of fresh gas in there. Do not fall for the carb cleaner additives since now that all gas has alcohol in it it already is a much better solvent than any additive. Of coarse it will go bad within a couple months now, 6 months max with stabilizer if you live in a damp area.

WyzrdX · July 31, 2015, 11:22 AM

Well I think I have it fixed for the time being. I sprayed carburetor cleaner inside and out. Put half a tank of fuel and drove it for about 35 miles one way and 35 miles back. The next morning went out for another quick drive and not once did it die on me. When I got back home, I shut it off, tried to restart and it did.

Haven't had to choke it since using the cleaner. I am not expecting that to be a cure-all but it has made it easier to move around and not have to remove the doghouse.