Old Jacobs L-4.

This 225 hp Jacobs L-4 came with my Staggerwing project, 1934 B17L serial number 12. This aircraft was converted to a 245 hp L-4MB in 1946. The previous owner of the project intended to put the L-4 back on the Staggerwing to make it as original. I plan to stick with the L4-MB. During this conversion in 1946 the Staggerwing flew with an experimental registration. The L-4 is a "greaser motor"; all 14 of the valve rocker arms have to be greased every 10 hr of flight time. The L-4 has a dual battery ignition system. The L-4MB has one magneto and one battery ignition.

My father told me of one problem with these early Staggerwings with the L-4. If you took off with a low battery, then started retracting the landing gears, the gear motor load could reduce the available voltage to the point that the ignition system would start to fail.

I have the second log book for this engine. It was removed from a YKS-7 WACO NC17737 in Jan 1945. It had a factory overhaul and was installed on another WACO, a YKS-6 NC16598. The last log book entries are in 1950.