Cold Start Issues
...if there is a fuel delivery problem at first start up, wouldnt there also be fuel delivery issues during normal operation of the vehicle? From experience a pumps performance is what it is, it really doesnt change.
Correct. As long as there is fuel in the bowl it should fire up in a try or two.
I was aware that to set the choke you have to depress the gas pedal to set it. Unfortunately I dont have much experience determining the cause when something isnt working the way it should.
I know when I depress the gas pedal the choke blades close. The problem is I am the only one over there trying to get the thing started, so I never had the extra pair of eyes to determine if and when the choke comes off. Appears I may need to contract some help (or a starter button). However when I am playing with the throttle when it is cold it is hard to determine if the fast idle is the least bit engaged.
Take off the aircleaner if needed. Do not try to start the car. Work the throttle lever on the side of the carb with your hand. The choke should close and fast idle screw should be sitting on the step of the fast idle cam. If these settings aren't pretty close, the rest won't work right either.
Starting the car:
Have you tried just giving it a few extra shots of gasoline by working the throttle? With the air cleaner lid off, you should see fuel shooting out the accelerator pumps as the throttle is opened quickly.
OK. go and start the car. You can put the lid back on loose or leave it off. Put the wingnut where you wont loose it or drop it into the carb. Do not look down the carb while cranking.
You can just start it from inside; or if you want to be right there under the hood, put the key in run position and use a remote starter switch or screwdriver to jumper the relay.
As soon as the engine starts the choke will be pulled slightly further open by a vacuum operated link. After 10 -20 seconds try tapping the throttle to see if the choke's bimetal coil has moved enough to let the fast idle screw sit on the next step down.
The initial timing is set at 12-15 deg BTC.
Since this is a modified engine, that's about right, maybe. At some point measure the timing and rpm so know what it actually is.
1. The choke is bad and not letting it start. It is coming off to soon hence why I have to keep playing with the throttle until the car is warmed up.
2. The choke unloader is bad (or set wrong). and unloading the choke to soon, causing a similar issue to theory 1. - confession, not to sure if that is even possible.
3. The carb float valve is sticking closed. Not allowing fuel to fill the bowl until the engine starts, and the added vacuum forces it open.
4. There is a leak in the carb somewhere that allows the fuel to vaporize
1. To say the choke is bad is too general. It's initial position, and/or the fast idle position just may not be set correctly and thats why it doesn't start.
2. Choke unloader usually is mechanical lever that forces the choke fully open when the throttle is held fully open. Its for clearing an intake which has been flooded with too much fuel. The vacuum motor that opens the choke further after start is called the choke qualifier.
3. No. Fuel should remain in the bowls. Although given enough time the lightest, most easily ignited components will evaporate. Easy enough to check for fuel in the bowls.
a. Remove air cleaner lid and work the throttle. If the accelerator pumps have fuel, the bowl has some fuel. The pump itself only holds enough for a few shots at most.
b. Remove the carb top and look.
4. Older carbs have open fuel bowl vents and open air cleaners. So yes, they lose more fuel to evaporation than later systems. Same with the intake manifold.
Lots of additional tips about carburators and chokes, as well as explanations for the concepts can be found here:
Master Technician Service Conference - Chrysler's Training for Mechanics
The filmstrips and movies often supplement the pamphlets, although some cover the almost exact same thing.
Particularly good to look at will be the 1970 Carburation Fundementals and 1969 Finer points of four barrels.
