Need a Stromberg carb guru. The rear carb on my '74 series 2 is not working right; I had been running the car on the front carb with the rear inlet throat blocked off, and tried again to start the car using BOTH carbs. The rear carb piston raised to full throttle on startup and refused to return to a closed state. I had the car running at WOT only as long as it took to shut the ignition off.This carb has been doing this since I rebuilt them BOTH shortly after obtaining the car in March of 2015. I have been advised to swap pistons between the two to see if the problem persists, but have not tried that yet. I was under the assumption that the piston relied on the airflow through the carb to establish vacuum to raise, and the throttle plate was and is closed on startup. The piston is very resistant to dropping on it's own.

 

realizing that, once I suss this item out, I will be a Stromberg guru

 

Sounds like an off centre or bent needle or incorrectly centred jet. IIRC the needle is supposed to be free to self-centre.

Been many many years since I played with strombergs!

 

Curt, when you rebuilt the carbs, did you seat the diaphragm properly???
There is a little pip that needs to locate!

You did refit the piston return spring ???