[HO455]

More on the choke pull off modification. I decided that the 1 second bleed off rate was still to slow so I drilled it out to .018. That definitely made it quicker. It was actually was too fast for me to get an accurate measurement with the stop watch function on my phone. But it was definitely less than one second. I reinstalled the choke pull off and now I'm driving it for a couple of days to get a good idea of how it's working.
I want to point out that drilling the orifices is not as simple to get the ideal result as it may seem to be.
When I drilled the .0135 hole out to .0145 I changed the area of the hole 15.37%.
When I drilled the .0145 hole out to .0160 I changed the area of the hole 22.09%
When I drilled the .0160 hole out to .0180 I changed the area of the hole 26.20%
As you can see every step larger makes a much larger increase over the last step. Something to keep in mind if you are performing this modification. Back in the day it was easy to get a another pull off at the wrecking yard for a buck or two if I drilled one out too big. These days the wrecking yards are empty when it comes to Qjets and new pull offs are twenty bucks a pop.
At this time I readjusted the spring tension on the secondary flapper. The tension is controlled by a small screw next to the flapper shaft. The screw is locked in place with a allen set screw. (Photo #1 spring tension screw blue arrow, set screw red arrow.) I was looking for the least tension on the flapper that would still allow it to return the flapper to the closed position. This is my base line starting point. The idea is to get the secondaries to open as fast as possible with out causing the engine to stumble or bog. It is a balancing act as what might work perfectly when you punch it on the freeway may be to quick for off the line causing the engine to fall on its face.
The dreaded Quadrabog!
More to follow.