One of the topics asked about is the 426 Hemi engine’s fuel pump.
From 1966-1971 the 426 Hemi Engine used a mechanical fuel pump manufactured by the Carter Company. It’s a diaphragm type with the model number MS-4024S. The fuel pump contains 3 valves, is driven by the camshaft and has 6 1/2 to 8 1/2 pump pressure pounds depending on the year.
The rest of this article will explore the fuel pump in more detail including its construction, inlet, outlets and date codes.
426 Hemi Fuel Pump Specifications and Facts
The 426 Street Hemi Engine used a mechanical fuel pump for all of its productions years, 1966-1971.
The pump was made by the Carter Company. The table below includes all the specifications for each year.
|Number of Valves
|Pump Pressure (pounds)
|7 to 8 1/2 (1967-1971)
6 1/2 to 8 (1966)
The fuel pump attaches to the engine block with two bolts. The torque specification for the bolts is 30 foot pounds. The thread size is 3/8.
The fuel pump has one fuel inlet and one fuel outlet. The inlet is at the bottom and part of the cover. The word “in” is cast underneath the inlet opening.
The outlet is part of the valve body and the word “out” is cast underneath the outlet opening.
The fuel pump is driven by an eccentric cam cast on the camshaft. There is a pushrod between the eccentric cam and fuel pump rocker arm. As the camshaft rotates, the pushrod presses on the fuel pump rocker arm activating the pumping action.
Fuel Pump Parts
The fuel pump consists of the following parts:
- Rocker arm housing which attaches to the engine block.
- Rocker arm.
- Follower spring.
- Pivot pin.
- Diaphragm and pull rod assembly.
- Valve body.
- Valve assemblies.
- Air dome diaphragm.
- Cover at the bottom.
- Assembly screws.
426 Hemi Fuel Pump Part Number and Location
The part number, MS-4024S for 1967-1971 or M-4024S for 1966, can be found on the fuel pump.
Typically, only the numbers 4024 is stamped into the upper rocker arm housing. It is found underneath the housing and to the side close to where the housing meets the engine block.
426 Hemi Fuel Pump Date Codes and Location
The fuel pump date code consists of a letter and a number. The letter indicates the month and the number indicates the last number of the year.
- For example, a date code of D9 indicates April 1969.
The date code is typically located on the upper rocker arm housing. It is found underneath the housing and to the side opposite of the part or model number.
The date code is close to where the housing meets the engine block.
Read more Mopar engine fuel pump articles:
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For the past 40 years, I’ve been studying and researching Mopar engines including the 426 Hemi. I installed my first Mopar fuel pump 38 years ago while building my first Mopar engine.
More Mopar Engine Articles
- Chrysler Service Manuals: 1969-1971
- Google Books: Chrysler Engines 1922-1998
- Wikipedia: Chrysler B engine