Helpful tips for all Atomic 4 owners
This Tech Tip, one of an ongoing series we publish, is for Atomic 4 owners who were wanted to upgrade their carburetor and convert their mechanical fuel pump to an electrical unit. Today, these are less common, but we wanted to maintain this information so the shrinking pool of owners could still find the information they needed.
Carburetors
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 found a new rust-resistant aluminum die-cast carburetor. This Zenith carburetor (Universal PN U288482) will replace all of the now obsolete earlier carburetors without any changes or modifications. 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, however there are some electrical fuel pumps available to replace it. These pumps typically install easily and usually contain a built-in fuel filter.
To install this pump, you may need to 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, you might 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.
