Stuck choke- Zeniths
Walter,
Chokes won't cause an idle near 3k.
By adding starting fluid to start, you're changing the fuel mixture enough to start the engine. Which means there's too much air ( bad air; from some other abnormal source).
Too much air-
1) Linkage out of adjustment holding something open that should be closed or near closed.
a) Accelerator pedal where it should be and returns back when depressed?
b) Main linkage to left motor mount have a spring on it?
c) Is the linkage bent?
d) Is the adjustment screw on the throttle rod ( under the fuel t- fitting) touching? There must be a gap as this is what you use to increase the idle speed and set the timing.
e) Links from the rod- are they down all the way? Push them down with your hand or thumb. All these parts are old and sometimes they act up even when you clean them and grease them up.
2) Carbs- Since the engine runs at 3k: Does it run normal or stumbles and shakes? Since you say it runs, lets assume it's something effecting both carbs.
a) Gas-Let's assume it's getting fuel and the bowls are full. Weak mixture. Too much air. Adding starting fluid and starts.
At 3k, the carbs are well into the middle of the primaries and the idle circuit is working.
The throttles are staying open for some reason other than linkage. Jammed, loose on the shaft and jammed. At idle position, the plates are mainly closed and the primary circuit isn't used. Gently push the plates and see if they close.
The opposite can occur to air- not enough fuel; if the idle circuit is plugged or the solenoids aren't working or powered then too much air is in the mix and starting won't occur easily. Hence the need for the starting fluid. Check for power at each solonoid. A trick is to close the small air bleed hole next to the idle air jet on the top of the carb. Use a piece of metal tape preferably than your finger. Then try to start. If it does you know somethings wrong with that circuit.
Last but not least are the secondaries which can jam or hang up. But only when they've been opened and won't close ( partially). If this is the case, then air is being drawn when it shouldn't. Since there are two barrels and the secondaries can effect idle, speed, mixture this can be the cause of a high idle, sync., roughness, etc. An easy way to check if you don't have an air meter is to choke down the opening and see if it changes. ( Take away the extra air.) They can hang up on linkage, in the bore, or a plate is partially loose. Gently, push down on the plates and see it they close.
These cars are old ( But very much loved and admired by many) and wear occurrs where the factory never dreamed of and it's not all in the manuals. Many people have worked on these cars some with great care and some with less so it pays to check the not so obvious. Persistance in solving the problem will get you there. This is a great forum for people of all experiences to share knowledge.
Here's my cell- 713 885-2016. I'm happy to help you in any way I know how including standing next to my engine and walking you through it on the phone.
FYI- My car ( 72 CS) came from S. Maryland and I used to live in Falls Church, Va, so don't be a stranger if you have a question or get stumped.
61porsche
