Hi can any one fill me in on how the secondary section opens on the carby when driving. The carby is off a A15 Vanette with auto choke. It has a vacuum mechanism that when I apply vac to it, it opens the second butterfly and sprays fuel in and engine revvs up from idle. The vac diaphragm is connected close to the bace of the carby and from what I've checked it does not have vac at idle or off idle. While stationary and revving the engine I can't see the secondaries open unless full throttle is hit and a lever slightly opens the secondaries but the vac diaphragm seems to be doing nothing. What are your thoughts?

This is the Hitachi DCR306. The secondaries are operated like any other vacuum secondary carb, via LOAD and AIRFLOW. The vacuum is generated by the primary venturi, so it wont activate without a load.

Yup, what he said. Here is a helpful illustration:

Thanks for the info guys, that makes sense now. If I put a vac gauge in line, how much vac should I see under load. The car is running fine, just seems a little sluggish and the 3 speed auto does not help much.

There should be no access point for you to put a gauge in-line with this system. As with all engines, eliminate the easy things before moving into the carb. Timing & spark, plugs, dizz advance operation, rocker clearance, compression and leak-down. Concentrating on secondary action at this point is getting way ahead of things. Do you know for certain that it is not running as well as the day it was new? Small engine + auto trans = get comfy cuz this trip up the on-ramp will take some time.

If the secondary is wired shut, it won't feel sluggish (just underpowered) -- try it and you'll see.

It was just a thought to put a t-piece in the vac line going from car to diaphragm to measure vacuum. Honestly I haven't checked anything was just looking at the carby and was trying to figure out how it worked. I was thinking about putting a weber on, but being auto I think it will be wasted money. I will stop the secondaries from opening and see how it feels on the road, I'm interested to see how much it does