Reversion?

[pmangelos]

Hello all,
I'm a long time lurker, love Cobra's but right now I have a Mustang I'm in the process of building and have a few Weber specific questions and you guys seem to have the best knowledge base anywhere on the net, so hopefully you won't mind a few questions. The car is a 65 Mustang with a 427W running 48 IDA's and am having what I perceive to be a problem. The engine runs very strong up to about 5500 rpm but then it falls on its face. I have the hood off the car right now and can see white puffs coming out the top of the carbs at the same time that this happens, the engine sort of coughs and doesn't want to keep revving. I have a feeling that I might be having valve float, but am not certain. I know Webers can be prone to reversion, could this be reversion by itself, and if so does reversion cause a significant decrease in the engines performance? Or is this likely valve float that is causing this?

Here are the specifics on the engine and cam:
427 Windsor, Canfield High Port heads, Full Length headers, MSD Ignition, Comp Cams Magnum roller rockers, Ford Racing roller lifters.
Custom Cam ordered specifically for use with Webers:
Hydraulic Roller
Lift: .603 Intake, .584 Exhaust
Duration 280 Intake, 291 Exhaust
Duration @ .050 227 Intake, 241 Exhaust
Lobe Separation: 115

The Webers are currently set up as follow:
40mm chokes
170 Main Jets
F-7 Emulsion tubes
140 Air
65 Idle
60 Idle Air
50 Pump Jets
60 Bleed Back
Electric pump with return line, set at 3 psi

It seems to me that this engine should pull to at least 6000-6200 rpm, am I wrong? It certainly wouldn't be the first time. Any advice is greatly appreciated, if you need any more info, please just ask.

Thank You in advance for your time,
Sincerely,
Paul