Q jet power piston spring

[Alan Roehrich]

Originally Posted by outlaw

Not sure but I would think that stocker a with a too light of a spring once it starts regaining vacuum on the top end would start plugging rods back down and lean it out. Lean is mean but so is the parts bill.
Terry

Well, few QuadraJet combinations are capable of moving so much air that a 750 or 800 cfm carburetor will become such a restriction that they generate more than 5"- 8" of vacuum, you MIGHT see that on one of the 454 Super Stock engines. If memory serves correct, the orange power piston spring, for example, will overcome 10" to 12" of vacuum. Remember, most 4 barrel carburetors are rated for cfm at 2.5" of vacuum.