When I'm under a high load the car likes to cut out and I can't figure out why. I rebuilt the top half of the carb, but it did this before that. I'm thinking maybe it's the fuel pump? I'm just not sure, I also thought it may be weak valve springs?(205,000mi) Any suggestions or tests I can run to find this problem, I'm tired of my friends 73 Caprice keeping up because I can't put the pedal to the floor, oh and this will usually only happen in the higher gears, I also thought it could be that my secondaries open past 90*(just a little, but it's noticable) Any advice would be greatly appreciated.

 

How much tension is on the air valve?

 

3/4 of a turn.