Car Requires Choke to run

[87mj]

I recently received z therapy carbs. I installed them with very little fanfare.  I was able to get the engine started pretty easily but I didn't fine tune the balance or mixture.  Then I replaced the choke cable for an unrelated reason.  Now that I am trying to adjust the carbs, I can't get it to run very well.

The valves have been adjusted and the timing was set.  It has new plugs and wires. The carbs were topped with oil and the vent caps were removed from the float bowls.

To adjust the carbs, I warmed the engine and was able to balance them, but the choke linkage needs to be slightly on in order to keep the engine running.  I started adjustment with the mixture adjustment screws completely up.  Then down 3 full turns.  With the choke off and the choke linkage not engaging the choke, the engine will not start with the mixture nuts in that position even when the engine is warm.

The only way I can keep it running is by turning the mixture nut counterclockwise (down) opening the jets several turns all the way to the limiting screw.  Then I loosen the choke cable retaining screws so that the choke linkage moves freely.  Then I slowly move each choke linkage up (ie on) until it idles by itself.  But it is not smooth.  

After setting the mixture screws, if I lift the piston slightly with the screwdriver tip, the car will stumble and die indicating it is too lean.  But visually, I have the carbs, and the choke adjusted rich.  When I drive it, I can feel a slight stumble and hesitation.

If I have the choke slightly pulled and/or the mixture set rich, RPM is at about 1500 at idle.  I can keep it running if I disconnect the choke from the carbs and screw the mixture nut all the way down.  But that is clearly greater than 2 1/2 - 3 turns. I haven't counted but 5 turns perhaps? But again, the idle is not smooth. The car is not smooth on the road either.

Anyone have any thoughts?  Thanks

[SteveJ]

Look for vacuum leaks all around your intake.

[siteunseen]

I've had similar and it turned out to be the float chamber lids screws were loose. There's 4 on each of mine, Phillips head. They vibrate loose after a whille I suppose if you haven't had them off or anything. 

Raise the piston on each carb and check for "equally shitty" running. One carb runs 3 cylinders so disabling them one at a time should give you equal crappy running. It'll run but barely.

Did the distributor hose come off the front carb? It does sound like extra air being pulled in from somewhere. High rpm is generally a result.

 

Edited September 9 by siteunseen

[87mj]

On 9/9/2024 at 2:09 PM, SteveJ said:

Look for vacuum leaks all around your intake.

One of my intake studs broke during reassembly as if it broke off 90% in 1980.   I decided to take it to a shop to have the gasket replaced.  I will report back.  I think he is on to something.