Ultra XP850 Almost there!
Can you explain in little more detail what main well taper is and how to get rid of it.
Thanks
When they cast the metering blocks the main well is smaller at the main jet than it is at the top.
They do that to get the metering block out of the mold. I forgot how much smaller it is at the bottom but it’s quite a bit.
IIRC I drill the main well out to .188 but I don’t have my notes in front of me.
I have to assume and maybe I’ll call Tuner tonight and ask him about it but my assumption is the fuel at the bottom of the well will weigh less than in the middle or the top for the same height of fuel.
In other words if we measure the main well in .100 increments the .100 at the bottom will weigh less than the .100 in the middle or the .100 at the top of the main well.
Since the emulsion holes are evenly spaced it’s my opinion (I’m probably wrong which is why I need to talk to Tuner) that since the weight and really even the volume of the fuel at different heights of the main well will be affected differently.
If the main well is the same diameter from top to bottom (no taper) then the fuel will be the same weight (and volume) for the entire length of the main well.
Or I’m just talking and thinking out of my hat.
Thinking about it, this may be covered in NACA Report 49. I have it printed at home and on my iPad but not on my phone.
I’ll call Tuner later tonight.
Edit: I drill the main well. I have thought about drilling and then finishing it with a reamer so it’s round, but that may be picking the fly poop out of the pepper.