Holley Power Valve, Selecting, Testing and Quality

[Argess]

I have a 2x4 Holley (4160s....600 cfm each) set-up on a 428, and I have two issues.

1/ Tuning Issue: Normally, when I roll on the throttle, I can feel the engine pick-up, and then suddenly more power comes on, and then again a bit after that. This has to do with ignition timing vs power valve selection, not vacuum secondary opening rate....at least assume so because the story leading up to this is very long......

2/ Intermittent Issue: Sometimes, when I accelerate, nothing happens, just burps and hesitates and nothing. Let off the gas, try again, and it seems OK. Sort of like misfiring, but I can rule out ignition as everything has been replaced.

So I tear down the carbs. Here's what I found:

1/ Primary float of second carb was adjusted for too high a fuel level. Also evidenced by fuel residue around external float bowl vent....one of those vents that opens when the throttle is opened. Had to turn down float level close to one turn to set float dry.

2/ Power valves from each car were not "blown". However, they had a microscopic stamp ( number about 1/32" high...very small) on the brass piece that holds the spring that said 5.5. Don't genuine Holley Power Valves have the number on the aluminum part you put the wrench on?

3/ Testing with a Mighty Vac showed operation around 3 in Hg for both valves. Mighty vac was checked against another guage and shown to be accurate.

Now, for a light car that has a 290 adv Cam, and I am getting close to 16 in Hg with my current intial ignition timing at idle. According to what I read, shouldn't 8.5 Power Valves be a better choice? According to my 1966 Ford Manual, the twin Holley set-up used #85 PVs.

So...here's some questions:

1/ If my current PV arn't genuine Holleys parts, could they leak, even when closed and cause flooding which may be the cause of my "sometimes" hesitation/misfire?

2/ If I purchase replacements, wouldn't 8.5s be a better choice?

3/ Do you think the one float level set as bit too high may have caused any issues?

By the way, these carbs came from a respectable carb company. They also used to work satisfactorily, but my ignition was very far advanced at that time, and I didn't know it.

Thank-you.