1. Home
  2. Carburetors
  3. Tillotson
  4. HL-Series
  5. HL-360B,C,D
  6. Tillotson High Volume(Double Stack, Alky)Diaphragm Cover Plate
Tillotson High Volume(Double Stack, Alky)Diaphragm Cover Plate
91A-303 Tillotson HW Diaphragm Cover Plate - Top
Write a Review

Tillotson High Volume(Double Stack, Alky)Diaphragm Cover Plate

Part Number: 91A-303
Your Price: $12.82
Diaphragm Cover Plate Double Stack Alky High Volume
Availability: In Stock.

Send to:

*We'll ask for shipping info at checkout


The Tillotson High Volume Diaphragm Cover Plate covers more than the main metering diaphragm. 

It's designed to have a larger pump area for the fuel pump diaphragm, which is why these carburetors are called high volume or, in some cases, double-stack or alky pump stacks. 

The double-stack refers to the additional plate that separates the fuel pump and check valves making complete unit two plates or double versus the single plate that holds both. Do not mix single and double stack plates. The design, gaskets, and diaphragms are exclusive to each fuel pump stack and will not work if mixed. 

They are also referred to as alky plates, but this is inaccurate. They are referred to as alky plates for the extra volume required to pump methanol vs. gas. The most accurate description is to call them high-volume pump plates or stacks. This plate style is for engines running gas or methanol that require higher fuel volumes to make the engine perform. 

If you convert a gas carburetor, you will want to use a high-volume plate. Using these plates is not the only modification you need to make for your carburetor to run methanol. 

91A-303 OE Tillotson Diaphragm Cover Plate fits all High Volume(Double Stack, Alky)Tillotson Carburetors. Check your carburetor and carburetor listing before ordering. 

Related Items

Recently Viewed Items