Double Pumping

Carburetors.  Archaic technology (hasn't been sold on a car since 1990) and very temperamental (hard to dial in).  I only say this because I have been having a hell of a time getting them to work for me.  I inherited with my car a Holley 4160 600 CFM which comes with vacuum secondaries.  This means the carb relies on the vacuum created at higher rpms to pull the fuel into the secondary fuel bowl (higher rpms require more fuel to be fed into the engine to meet the demand).  It is actually a pretty nice bit of engineering (for the time), and in theory the fuel is delivered when it is needed.  This was not the case for my 4160.  I am not sure if it was due to the lower vacuum my engine pulls because of the bigger cam, or what, but I could never get the secondaries to open on my carb.  I tried lighter springs and a new diaphragm, but I could never get it to work correctly.  It was costing me horsepower. And then one fateful day, the whole carb decided to die in spectacular fashion.  Gas just started spewing everywhere from every seal.  I had enough.

The old 4160