283 Stalls unless choked

My 1960 Corvette 283 with WCFB will not idle unless it is just about fully choked and then while at idle pulls about 18 on the vacuum gage. When I open the choke more than about 3/16" it dies. I've checked the intake with propane at every gasket and jetted propane under the manifold through the vent pipe opening next to the distributor and no leak is evident. I thought perhaps it was a carb problem so using an adapter I put on a good 2 barrel with the same result: When the engine is fully warmed up it stalls unless choked.
Background: I just replaced the timing chain and installed the correct intake manifold. I'm using a WCFB that I've rebuilt and double checked before testing with the 2 barrel mentioned above. I installed the distributor with #1 facing forward. The engine timing is correct and the compression is 125 on every cylinder. The engine has about 80,000 miles on it.

It sounds like the carb is pluged up . how do you no that the carb you used was good tha adpt could of leaked what you have described sounds like it carb have you rebuilted it you all so might check your fule pump

Does it have power brakes?...... If so try blocking off the hose
Just a thought

MM64 :cool:

It does not have power brakes and all the vacuum hoses have been pluged.

Well you may be right but if there is a leak between a head and the intake it sure seems like it would show up when I force propane into the cavity. I'm not using a spacer just a regular base gasket. The gasket has the two small holes for the exhaust circuit in addition to the 4 large holes. What do you think about my 125 compression?

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Originally posted by techinspector1
"installed the correct intake manifold"

This is when all the trouble started, right?
I'm bettin' that someone in the past has milled this manifold and that it's not sealing to the ports on the inside of the motor. I understand that you've injected propane there, but somehow I just can't believe that the problem is anywhere else. Bottom line is that you're gonna pull the manifold anyway, right? I'll betcha you'll find it didn't seal on the inside.

One last thought, are you using a carb spacer of any type? I've had to file the livin' bejesus out of those black phenolic spacers to get 'em to seal in the past.

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I never thought about those spacers Ive got two three of them they make good wall hanging :LOL: :LOL:

The float's stuck to the top of the bowl?? I've had this happen on overhauls with me. Carb sit's too long dry ( and only the carb can decide this amount of time) and it will stick.
Gas filter could be clogged. Just a couple of thoughts.

have you checked the fuel presser and fuel volume?

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Originally posted by DennyW
Hi guy's, I really like this site!!
Lets see, engine runs until it warms up. A couple more things you could check, the fuel line running to the rear, usually has a rubber hose. They will dry up, and crack, causing them to suck air with the fuel, so when the choke opens, you are to low in the bowl fuel level, and it dies.
The other is the sock in the tank. Just adding things to the other replies. And don't forget fuel pump volume check.

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hey dannyw, if he ant fixed it by now its to late:whacked: :LOL: :LOL:

Sounds like a huge vaccume leak to me,,,,fully choked,,,and it runs,,,kinda proves the point,,,,i'd look at the intake manifold,,,,as it is probably not sealing properly,,,,other than that,,,check all your hoses,,,you could have a split in one .
Either way,,,,your getting atmospheric from somewhere.