237-154 Tillotson High Volume(Double Stack, Alky) Fuel Pump Diaphragm is the actual diaphragm that is pumping fuel for the carburetor. 

The High Volume or what is known as a double stack has its fuel pump diaphragm separate from the fuel inlet/check valve diaphragm. This is the reason for the additional plate and different designs. 

This is what you will hear us call the “snakeskin” diaphragm as it resembles a snake’s skin is actually a Polytetrafluoroethylene(PTFE, Teflon™) material. This is the material of most stock Tillotson Carburetors we also offer Clear Polyethylene Terephthalate(PET, Mylar™) used on many of our built carburetors. 

It is common for carburetor builders to convert gas carburetors into running methanol which usually means changing the pump stacks on the carburetor. This pump is also required to make the conversion to use the high volume pump plates. We highly recommend buying a complete EC Pro Gasket or Rebuild when making the conversion. 

Tillotson High Volume(Double Stack, Alky) Fuel Pump Diaphragm fits HL-304WX,WXA, HL-314F&G,HL-334WXA, HL-339A,HL-341A,HL-342A,HL-348A,B,C,D,E, HL-355A,B,C,D,E, HL-360B,C, HL-380A,B HR-181B, HR-184A, HR190A, HR-191C, HR-191G, HR-196A and other High Volume(Double Stack, Alky) Tillotson Carburetor