dch306 question

[bob3d]

I have a 78 b210 my mother bought new. It's in excellent condition and I enjoy keeping it that way. I am wondering why the aux butterfly valve on the secondary doesn't open when the secondary on the throttle body opens. It has that little arm with the disc shaped weight on the side of the carb and it moves easily and opens the valve. Apparently it's operated by airflow/vacuum at high rpms. Car runs great but i'm not getting proper secondary operation. Please help.

[datzenmike]

Um... in order to see it working under heavy load you would have to take the hood and air filter off and ride in the engine compartment. Revving it in neutral, no matter how high, is rarely enough. It's probably just fine.

[kelowg]

Just make sure it moves freely. maybe some spray lube. 

[bob3d]

Thanks, so I hope its working under a load then I'll try to think of a way to "witness it" . It moves freely. Might mount a small video camera to see if the arm moves while driving.

[datzenmike]

Yes. Someone did this with an SU carb. All you need is to see the linkage on the outside move.

[bob3d]

Got a better idea. Costco has an inspection camera on sale with a 3 foot optical cable. I'll run it through the firewall. Going there now.

 

 

Followup-   I zip tied the fiber optic to view the linkage, taped the monitor to my windshield and drove around. The camera showed the secondary flapper arm was responding correctly when I floored it.

[datzenmike]

As it should. It's hard to load the engine enough in neutral and revving it.

[Cosmonaut]

Your mother mayhave seldomely used the secondaries...Probably varnished up the secondary jet & or secondary inlet.

 

Time for a carburator rebuild?