A few months back I got a 3310 VS 750 holley. I finally got around to getting another dual fuel line and went to modifying the carb.

A small list of things I did to this carb so you guys can tell me if I screwed up somewhere.

1. Converted to an electric choke, (doner 80457) drilled carb body to mount vac line from choke like the 457 had. The 750 body did have an indention for the port but it was not used since it was a manual choke carb.

2. Converted to a 50cc accelerator pump, linkage and brown cam.
3. Replaced the primary metering block with the one from the 890457 since this one that came on the carb had damage to the jet threads.
4. Replaced the secondary diaphragm with the doner housing and installed a black spring for a base setup. Also to add a tad of chrome to the back of the carb.
5. The throttle shaft linkage was damaged so I used the shaft from the 457 wich bolted up nicely.

Now it runs great in the primaries but in the secondaries it just falls flat and wont pickup at all. It doesent matter what RPM I enguage the secondaries at either it just stumbles until I let off the gas.

I checked the obvious to make sure It had plenty of fuel and checked the SD to make sure it wasent bad. At Idle you can rev the engine by pushing the SD up and it doesent stuble like a passage is plugged. I attempted a lighter spring to see if it was lean no change. I put two black springs togather and no change.

What gives?

Sounds like the check ball is missing from the secondary housing vacuum port.

That could be it. I dont remember seeing one there when I swaped the springs. I'll have to check it out.