Good questions I never looked til now.
On my 6390 Holley 390cfm:
* See pump cam chart

http://www.holley.com/data/Products/Technical/PumpCamGraph.pdf

My cam looked beige/white but that was just 40 years of color fade. Its a #290 which is the Green/Olive cam, see chart, so its fairly healthy. In the Trick Kit they give you a #266 Orange cam which looks pretty close.

My power valves IIRC are 6.5 primary and 4.5 secondary. No particular reason, I just grabbed the two new ones that were in my spares box. The PVCR's on this carb are fairly small and the carb is so responsive, it really doesnt care when the power valves open, theres no flat spots.

Ideally I'd lean the primary jets down from #52 to say #50 or #48 for gas mileage, then drill the PVCR to match, THEN the PV open vacuum might matter more.

My experience with PV timing is it is very dependent on car, engine, cam, timing curve, jetting, even weather. No "rules" you just have to give each car&carb what it wants.


EDIT
On searching a little more, now I'm not sure if I trust the Holley chart or not, it is inconsistent with their own "light to heavy" list
http://www.holley.com/20-12.asp

Further discussion here

http://www.theturboforums.com/threads/332213-pump-cam-chart-vs-fuel-volume

http://www.chevelles.com/forums/archive/index.php/t-313242.html

So all I can say is, the 290 Green/Olive cam is working good in my 390cfm carb. I think someday I will have to measure the curves, lift vs throttle, and see if the Holley chart is right or mixed up!

Last edited by DeuceCoupe; 07/10/13 10:37 AM.