JACOBS R755 & R915

FUEL INJECTION

Fuel injection for the Jacobs engine has resulted in the greatest improvement to the Jacobs engine design in the past 65 years. The system produces a significant power increase, reduced fuel consumption, reduced cylinder maintenance, and a very smooth running engine. See the Fuel Injection link for full details.

R755 L4MB TO R755B2 CONVERSION

This FAA approved procedure authorizes us to convert the original 245 hp L4 engine (R755-9) to the modern 275 hp R755B2 engine and incorporate the improvements that come with that later engine model.

HARDENED VALVE SEATS

By replacing the original aluminum bronze exhaust valve seats with a modern stainless steel seat, valve seat erosion has been minimized, carbon and lead deposits are not able to adhere to the seat, and exhaust valve leaks are greatly reduced.

ENGINE BAFFLE MODIFICATION

By trimming the lower section from the engine baffles and replacing the aluminum with a rubberized baffle seal, it is now possible to retorque the cylinder base nuts without removing the baffles. Since the nuts need to be retorqued every 100 hours, a $6000 labor saving can be realized over the life of the engine and the baffle mod encourages regular cylinder base nut maintenance.

INTAKE PIPE DRAIN MODIFICATION

Engine liquid locks have been the Achilles heel of the radial engine design. By installing automatic drains on both the #4 and #5 intake pipes, oil no longer collects in these pipes and causes liquid lock, but rather drains to the back of the cowling where it can be collected.

JASCO ALTERNATOR MODIFICATION

The Jasco alternator has become the most common replacement for the original generator on the Jacobs engine. In addition to its lighter weight (1/2 that of the generator) the Jasco also charges at a much slower speed. However, the Jasco is larger in diameter than the generator and requires that both the oil pump and accessory drive housing be milled to clearance them. This mod approves the machining procecss.

IMPROVED OIL SEALS

The original oil seals for the magneto and generator drive gears were leather seals that retained moisture, caused corrosion on the gears, and hardened with age. A modern nitrile rubber seal is now approved that directly replaces the original leather seal.

ALTERNATE OIL RING

By replacing the original ventilated rib type oil ring with a modern expander type oil ring, oil consumption is reduced and better oil control is maintained.

BALANCING

All reciprocating and rotating engine assemblies are balanced to within 4 grams of one another. This produces an exceptionally smooth running engine free from the vibration characteristics of engines assembled from unbalanced random parts.