I have a holley 465 that I am converting to propane. To do this I have to change the linkage from vacuum secondaries to manual secondaries.
I can easily convert it to open all 4 butterflies at the same time but I have always though that the secondaries should hit at about half throttle.
Or did Holley ever make a 465 manual secodaries????

Any ideas?

if i remember corectly, you can swap in man throtle shafts etc.. this would prob work in your case since you basicly need it just as a throtle body.. i wouldnt ever recomend doing this on an actual "carb" ie: there wouldnt be any acc pump circuit etc..