B210 Fuel issue?

[Cypress Overdrive]

Just got a 1976 B210 about 4 months ago recently it came down with an odd issue it wants to die when you get off the gas, not only that it gets to where it sounds like it wants to die. So far we rebuilt the carb, changed fuel filter,spark plugs and wires and adjusted the points. but it still wants to die on us. I miss having this car on the road and we need help because I am out of ideas. Any help would be awsome

 

Thanks

B

[datzenmike]

The following adjustments or checks should be on a fully warmed up engine with the choke fully OFF. Take top off air filter and look. Choke plate should be vertical.

 

 

Not part open...

 

 

 

Good strong idle....

 

Valve lash..... Must be set to proper clearance. A tight valve does not close properly. If not fully closed tight it can't seal in the explosion of gas and air inside where it can do work. Set lash on a hot engine is best.

 

Ignition timing..... If not timed properly the explosion inside the combustion chamber is too late and the expanding gasses are chasing the rapidly accelerating piston down the cylinder. The maximum pressure should be at about 15 degrees after top dead center (TDC) while the piston is nearby and can be pushed on. To get this high pressure 'sweet spot' the spark plug fires somewhere before TDC as it takes a finite time for the fuel air to ignite and burn thoroughly. Engine idle should be within spec for this so that vacuum advance and centrifugal advance are not involved.

 

Idle mixture..... At idle, it doesn't take very much air and gas to keep the engine turning. If the mixture is even slightly too rich or too lean it will idle poorly or not at all. Find the idle mixture screw and the idle speed screw. Turn the idle mix in and out slowly to find the strongest smoothest fastest idle position. This position may be through one complete turn so just roughly se in the middle. Turn the idle speed down and repeat the idle mix adjustment. Find the fastest smooth idle, turn the idle speed back down. Keep repeating until you cannot improve the idle quality and the idle is around 800. Engine at operating temperature

 

You may need to adjust the idle mixture just so the idle speed is correct in order to set the ignition timing. However you will need to re adjust the idle mixture and idle speed after setting the timing. Any timing adjustment will change the idle speed.

 

EGR.... Is an opening in the intake with a spring loaded valve. Is not in operation during idle BUT the EGR valve MUST be tightly closed or intake vacuum will be lost. The EGR passes inert exhaust gasses into the intake and can become crusted with deposits and not seal properly. It's recommended that the EGR be removed and wire brushed clean every 30K miles.

 

Vacuum lines.... ANY hoses connected to the intake should be inspected for cracks or looseness. A vacuum leak is sure to cause a poor idle. Sometimes just pinching the hose near the intake connection can identify the one with the leak.

[Cypress Overdrive]

Thanks, I will give these a shot and get back to you. 

[racerx]

Or spray some brake cleaner around carb, base, hoses and intake. If rpm goes up, theres a vacuum leak

[Cosmonaut]

Many of those old carbs wind up having a loose throttle shaft, they do okay until someone unexpectedly cleans the carb (like a dip in Berrymans) and the crud gets cleared out...WA LA a vacuum leak that wont allow you to get the car into tune....

 

Spray like said above around the throttle shaft. If the idle goes up significantly, you have a worn shaft. If you look around your town/city you should be able to find someone that can install a seal/sleeve on it and bring it back to acceptable clearance.