Hi everyone, I have a 1958 172 and the engine log book shows an 0300b, however it has a prop governor on it? I thought that only came on a limited number of 0300e models? Any thoughts?

Thanks,

Jerry

Have you checked to make sure the engine serial number actually matches the log book?

Yes, numbers match.

There was some 0-300Bs that has provisions for a 2 position prop. So its not so much a prop governor, more of a high/low switch.

Thanks!
Do you know what manufacturer made the props?

My guess would be an early Aeromatic prop, I think the original ones where two position.

I believe it was a McCauley, and none available for quite some time as far as I know.

Aeromatic props are self-controlling, no hydraulics needed.
I believe the lever in question is only on the C145-2H and the O300B.
Check the engine TCDS, note 4:
"NOTE 4. Model designation suffix "H" on model C145-2 denotes the incorporation of crankcase and crankshaft
provisions for use of a hydraulically controllable propeller from the engine oil pressure. Model designation
suffix "P" denotes engine eligible for pusher installation as permitted by a special crankcase and front main
bearing."
and note 6:
"NOTE 6. O-300-A is similar to C145-2 except parts material and ignition component substitutions. O-300-B is similar
to O-300-A except incorporates crankcase and crankshaft provisions for use of a hydraulically controllable
propeller from the engine oil pressure. O-300-C is identical to O-300-A except for propeller flange provision
as indicated. O-300-D is similar to O-300-C except for provisions for Continental right angle automatic
engagement starter drive which incorporates a vacuum pump drive. O-300-E is similar to O-300-D except
for incorporation of governor drive pad and crankshaft provisions to supply governor oil to propeller"

If you check the C170 TCDS, you'll find that it includes approval for a McCauley 2-speed controllable prop:
"*(d) McCauley two-position controllable, hub 2B36C7, blades
78K-2 (Models 170A and 170B landplane and skiplane
with C-145-2H engine)
Pitch settings at 30 in. sta.:
low 13°, high 17.5°
Diameter: Not over 76 in., not under 74.5 in.
Item 108 with seaplane lip and Item 402(j) required."