I have a 65 Olds 330 with Quad 4 Barrel. The forward portion choke tube is attached to the electronic choke control on the side of the carb. The rear portion of the choke tube toward the firewall has a small cover with a concave surface (end of tube is open under cover). The car runs great if i disconnect the forward portion that connects to the electric choke mechanism and plug where it screws to choke. Needless to say it does not cold start well. If I hook the tube up to the electic choke it colds starts good but runs bad after warm up. Should there be something under that cover to prevent the loss of vacumn? Any Ideas?

 

The first question is, what do you really have? A stock 65 would not have had an electric choke. Is it really electric, which would not be stock, or is it the factory hot air choke with the black plastic choke coil cover?

The stock carb would have been a Rochester 4GC, not a Q-jet. Is that what you have? A picture would go a long way here.

 

Pictures for joe of carb and choke area

 

That looks to be the stock setup. There's no engine vacuum in that metal tube, it just sends heated air to the coil in the choke housing. The depression in the intake is directly over the exhaust crossover passage so it heats up fast, sending hot air through the tube to the metal coil inside the choke housing. The coil expands and moves the linkage which opens the choke butterfly in the top of the carb.

Are you saying if you don't hook up the choke the engine runs OK warm but if you do hook it up it runs rough when warm? That sounds like the choke isn't releasing after the engine warms up. Most likely the coil (under the black cover) needs to be adjusted.
See pages 7 & 8 of this link for 4GC choke adjustment instructions: http://www.pontiacsafari.com/L1Early...hester%204.pdf

 

Thanks to all that gave help on this.
I took the choke tube piece that had broken off and added a copper sleve inside so it would fit in the block portion then sealed with RTV. I think that i was getting a small amount of vacuum loss at this point. All that said I let the sealant cure for 2 days and re adjusted the air fuel mixture per the link given to me by copper 128 which was very helpful. The engine cold starts and runs like a scalded dog.