Nice trick for a 4150 holley

You know how it is. You go searching around trying to find something out and find something else instead. found this trick, that i wish i had found before i gave up on my vacuum secondary Holley!
found it. here
Frequently Asked Questions

Question: I can rev the engine when it is in park and the secondaries will not open. Why is this?

Answer: The secondaries will not open by free revving the engine. The engine needs to be under a load before they will open. If you are still uncertain if they are opening or not you can take a normal paperclip and clip it onto the secondary diaphragm rod. You will then push it up against the bottom of the secondary diaphragm housing, now you will need to go out and drive the vehicle. When you return you will be able to look at the position of the paperclip on the rod. If it is lower on the rod then you can tell the secondaries opened and how far they opened. This is useful in determining if you need a heavier or lighter secondary spring. For additional information, you can watch our video on Holley TV that explains all about the vacuum secondary system on 4150 carbs.

I have alway wanted to know just how far the secondaries were opening, when i was running my 4150 carb.
I didn't copy the video link cause it don't work any more.

A simple paper clip, what a concept!!!