Engine not idling

[jjohn]

Starting up the engine for the first time.
Full choke and 2 turns and the motor starts up. Oil pressure over 4.
When I close the choke to 50 % it still runs and I can increase the speed.

But when I try to close the choke the motor stops and will not idle.  Can it depend on e.g. air leakage? 

[Russ T. Fender]

Do you have a fuel filter in line?  Could be a lot of things.  What carburetor are you running?  Did you try the simple fix first by richening the mixture? Assuming that you are just restarting after a winter hiatus and that everything was OK when you shut it down last I have to suspect a restriction in the fuel line.  If my assumption is incorrect then I would check float level and intake manifold leak.

[Touring29]

You mean open the choke? When the knob is in its open closed when out. Our car will idle but won't speed up when its cold even with a little choke. Let it run a few minutes and its good to go.
 
Was the distributer out? Setting the timing is tricky. You have to get the screw out over the #4 piston and use a dial indicator turn the motor so that the #4 piston is .050 below TDC on the exhaust stroke. Then you turn the distributor until the points just break with the rotor pointing to the #1 terminal. The points gap to .020. Make sure the cable to the dist is working correctly.

Make sure you don't have a vacuum leak from the manifold to the block. Check it with carb cleaner with it running and see if the rpm changes.

If it has the original RT-08 Carter carb and you take it apart be carful some of the parts are pot metal and fragile. I had a problem with the float hanging on the piece it goes around with the main jet in it. I smoothed it up so the float couldn't hang on it.

Good luck these old things are simple but can be a little finicky.

[jjohn]

The motor is rebuilt. The carburetor is RT-08 Carter original with some new parts inside.
Yes, I have checked with a dial indicator that the #4 piston is .050 below TDC.
I have a 2 fuel filter in line with the carburetor. Maybe as you say @Touring29 it could be a leakage somewhere?

I have a plastic cup instead of the brass cup (temporary) and can see how the float level works inside the cup.

If I need to buy e.g a Zenith (24 T-2?) - do you know what kind of model I can use? (or other models )

[Articifer Tom]

Use a light or VOM meter to set point as you turn to break . Easier and more accurate then looking .
  When has it worked correctly ? Did it start after rebuild or carb parts ?

[jjohn]

This was the first time I have started the motor after buying this car. It has been in a warehouse for over 60 years or more. Someone has disassembled the car long time ago.

So the motor starts up directly after the rebuild but do not go on lower speed

[chetbrz]

Could be a vacuum leak. 

Maybe intake manifold gasket or carburetor gasket or some other possible point.  Maybe the point where the wiper line connects to the intake manifold.

My 2 cents

[Touring29]

This was the first time I have started the motor after buying this car. It has been in a warehouse for over 60 years or more. Someone has disassembled the car long time ago.

So the motor starts up directly after the rebuild but do not go on lower speed

What a find!
 As Tom said a light or meter is the best way to see when the points open. Usually a timing problem will show itself more at higher rpm than idle. They will idle with the timing pretty far off either way. It sounds like a vacuum leak is a good possibility. There are some little rings that go between the manifold and the block. I have heard of them sticking out too far if the gasket is thinner than factory and causing a leak. There are only 4 bolts or studs that hold the manifold on to the block. Check that those rings aren't causing a problem. As Chet said check the vacuum line if it has one. Don't give up these things run really nice when they are right.

I don't know what other carbs will work but I know there are some that will. I'll bet you can get the Carter to work.

[Articifer Tom]

Vacuum leak I would think make for hard starting if at all  . I wonder if if carb idle tube was changed . There are three critical orifices on that tube alone, that control until accel. is brought it to circuit .

[Russ T. Fender]

I know this may sound to obvious but have you tried adjusting the idle adjustment screw on the carburetor.  I don't know how familiar you are with these carburetors but it is the one screw just below the mounting flange.  Other than the idle stop screw it is the only adjustment you can make externally on these carburetors. If you are running a vacuum tank and have a gas filter between it and the carburetor (other than the glass sediment bowl on the vacuum tank) I would bypass it just to eliminate that as a possible cause. 
If you are looking for another carburetor to try you can run a Carter BB-1 but there are a few variations of it so you need to find one with the right throat size. I run one on my 30-U because I have never had much luck with the carburetor you have on your car although the issue was not idling but hesitation on acceleration.  After 3 rebuilds I finally gave up.

[Touring29]

I saw where someone said the RT-08 was the worst carburetor Carter ever made. I am amazed ours still runs after all the other things that have been replaced and usually done badly on our car. Ours hesitates some but we have got used to it. The way the accelerator pump works (or doesn't in most cases) is just weird. It shoots a puff of air into a channel with fuel in it and that pushes fuel out. I oiled the piston in ours up while I had it off and it sounds like it might work better. I'll know before long I am getting close to firing it up.

Hey Chet one thing I don't have is the strainer cap screw & gasket. Ours just has a piece of hose clamped to the nipple that sticks out. It works but looks bad. Do you have one you want to sell? I can't tell if the screw will tighten up or not since I don't have one.

[chetbrz]

Hey Chet one thing I don't have is the strainer cap screw & gasket. Ours just has a piece of hose clamped to the nipple that sticks out. It works but looks bad. Do you have one you want to sell? I can't tell if the screw will tighten up or not since I don't have one.

I'll see what I might have if I can remember where I put the leftovers.