My carb was recently rebuilt, and everything is great.. Once and a while, the secondaries will "stick", and the car has no power, I have jam the gas down a couple times to "un-stick" them. Does this mean I need a new secondary diaphram? Or is it something with the vacuum hoses?

Thanks for any help...
Matt

 

Matt - the secondaries on these carbs are driven by an internal vacuum passage. There are no external vacuum lines controlling the secondaries. If you want to be certain your secondaries are fully opening I would recommend changing your vacuum driven secondaries into mechanical secondaries. This process is very simple and takes less than five minutes but requires that you unbolt the carb from the intake. Except for occasionally experiencing a flat spot with acceleration it's well worth the effort and the ride is a lot more fun.

 

I have a "How To..." write-up on the mechanical secondaries, if you're interested. You do not need to remove the carb.

It is possible that in the rebuilding of the carb, something went wrong.
Possibilities include...

The spring located in the vacuum diaphragm housing is cocked, and not seated properly. The spring keeps the secondaries closed until there is sufficiant vacuum to overcome it.

The gasket that is between the vacuum secondary diaphragm housing and the carburetor housing is missing or torn. This would "disconnect" the vacuum signal, rendering the unit useless.

The gasket between the vacuum diaphragm housing and the cover itself (the gasket is in fact the edge of the diaphragm) is compromised. Same result as above.

The linkage at the bottom of the diaphragm housing is binding. Someone did not replace a washer to allow smooth motion of the arm, or something is too tight. Perhaps the arm has been bent.

The linkage on the other side of the carburetor is binding. Easy to do...a misplaced or absent washer causing binding; improper reassembly of the primary throttle shaft linkages create alignment problems, ect.

The throttle cable is misadjusted, allowing the primaries only to open partially. The secondaries will not not open fully, as the return spring located on the secodary throttle shaft is governed by a linkage to the primary shaft. Have someone put the pedal all the way down while you peek into the carb. Primary butterflies should be straight up and down. Secondaries should be very easy to move by hand, with just enough spring tension to close themselves.

All of this crap is explained in my write-up. PM me for a revised copy. It explaines a very cheap way to increase the capacity and stroke of your accelerator pump, as well; something that should go hand in hand with a mechanical secondary conversion but does'nt need to.
I will try to get it into the archives.

 

I'm going to say thats likely it from how it looked. I could make yours mechanical 2ndaries, but it was more then just a "dead spot" when driving it that way, not to mention a less low end response when mashing on the throttle.

 

Holley has web sight with a troubleshooting section. Gives a good run down of carb problems. If you can get by the word "cam" and" radical now" and then it still applies for the basic carb problems .