Tech Tip #34: Atomic 4 Carburetors and Pumps

Dr. Diesel
Written by Dr. Diesel

Helpful tips for all Atomic 4 owners

This Tech Tip, one of an ongoing series we publish, is for Atomic 4 owners desiring to upgrade their carburetor and convert their mechanical fuel pump to an electrical unit


Several different carburetors have been fitted over the years to Atomic 4 engines. While the original heavy, cast iron carburetors are no longer available, Foley offers a new rust-resistant aluminum die cast carburetor. This new Zenith carburetor (Universal PN U288482) will replace all of the now-obsolete earlier carburetors without any changes or modification. In fitting this new carburetor we recommend that a new in-line gas filter also be installed.

Fuel Pumps

The mechanical fuel pump for the Atomic 4 is also no longer available. Foley supplies a new electrical fuel pump to replace it. This pump installs easily and contains a built-in fuel filter.

To install this pump, fabricate a cover plate and install it with a gasket to cover the old pump hole. Use a 3½” length of 2″ channel as a spacer and mount the new electric pump on this piece, away from the engine. Drill and tap the outside flange of this spacer for 2¼” x 20 hex head bolts, spread 2½” apart.

To power the new fuel pump, pick up voltage from an oil switch located aft of the oil pressure adjustment screw, below and aft of the pump location. This feature prevents the engine from pumping gas should the engine stall. If there isn’t a 1/8″ NPT plug at this location, install a tee fitting in the threaded boss of the oil pressure sending unit, then thread the sending unit and the oil switch into the tee.

Dr. Diesel
Written by Dr. Diesel
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