I talked with Mark Whitener yesterday, we had a nice discussion. From Marks observations and flow measurementsTuner wrote: ↑Fri Mar 10, 2023 2:13 pmLOL "doesn't run right" covers a lot of territory. Every carburetor I see "doesn't run right" in the sense that everything can be improved in some way, large or small.
I haven't had one of these in my hands, so I am repeating hearsay. What I am told by folks who have had them on a flow bench is, particularly with the down-leg booster, the signal doesn't increase at the same rate as required by the increase in air flow and the result is it doesn't require a lot of "Too Much Emulsion" to cause the A/F to trend lean as WOT RPM increases, so a jet big enough for high RPM is too big at low RPM. The stronger signal of an annular booster works better in this body with the 1.600 ID venturi.
there appear two issues with the Holley 950 Ultra XP.
1. The Venturis are too large with the inlet angle being greater than 30*
2. Number 1 causes the Venturi bottom air flow to churn causing reversion.
3. The down leg booster being 1.60", possibly too large has poor signal 1 & 2 above.
There are possible solutions to the above which Mark and I discussed.
One possibility might be some sort of insert.
Mark also designed a booster that can be installed in this
carb to give it better signal.
There is also a different carb main body that can be used with the Holley 950 Ultra XP
that should work better than the factory main body.
These will be investigated at a later date.
Yes, I assumed Mark got busy doing TV Sports Audio. That is why I didn't pester him with
phone calls. We have similar background in TV, Basic Electronics, and production, etc.
--thx Spike