Ruidoso Ron
Registered User
Alto, NM
Can't find my manuals after a move. Please advise me what is the proper torque for the prop bolts on an O-320 Cub.
Proper prop bolt torque
- Thread starter Ruidoso Ron
- Start date
Ruidoso Ron
Registered User
Alto, NM
Thanks Dave, must be good........it flies! Got my 6.00X6's and cruise prop on, and increased the cruise by about 10-12 mph. Think my prop is too coarse at 56". Couldn't get over 2450 RPM in level flight, and the climb was way too slow here at 7,000'. May go repitch to 54" before departure for 8D1.
Ron.......
Ron,
A 10-12 mph increase is a substantial amount. What engine is in your cub, and what actual speed are you seeing now with the smaller tires and cruise prop?
As far as I know, the "rule of thumb" on prop pitches is that your aircraft will reach, but not exceed the engines maximum rpm, full throttle, at a low altitude. I had an old Cessna 170B that would run at 2700 rpm (135 mph) down low and full throttle. According to that "rule", the prop was perfect in pitch. I think a flatter pitch in your case is certainly in order.
Mike
Ron,
A 10-12 mph increase is a substantial amount. What engine is in your cub, and what actual speed are you seeing now with the smaller tires and cruise prop?
As far as I know, the "rule of thumb" on prop pitches is that your aircraft will reach, but not exceed the engines maximum rpm, full throttle, at a low altitude. I had an old Cessna 170B that would run at 2700 rpm (135 mph) down low and full throttle. According to that "rule", the prop was perfect in pitch. I think a flatter pitch in your case is certainly in order.
Mike
Ruidoso Ron
Registered User
Alto, NM
Mike,
Since my last posting, I had the prop repitched to 52". In addition to the prop, I switched the 26" Goodyears to 6.00X6's. (Looks funny now). Haven't had a real good chance to rag it out, but looks like cruise is around 102-105 mph at 2400 RPM. Static runup is about 2325 max, but this is with a DA of 9,300'. Max RPM in level flight, full throttle, at 8,500 is about 2550. This seems a little anemic. Would like to have seen another 100, or so. All other indications are good, and I am reserving judgement until I get a chance to see it down at SL. The trip to Nolstein, and back, should give me a good idea of how it's performing. Only question mark now I guess would be the camshaft. Looks as if the process of micing (sp?) the valve travel may be beyond my capability, and I'm sure not interested in a teardown at 300 SMOH.
Since my last posting, I had the prop repitched to 52". In addition to the prop, I switched the 26" Goodyears to 6.00X6's. (Looks funny now). Haven't had a real good chance to rag it out, but looks like cruise is around 102-105 mph at 2400 RPM. Static runup is about 2325 max, but this is with a DA of 9,300'. Max RPM in level flight, full throttle, at 8,500 is about 2550. This seems a little anemic. Would like to have seen another 100, or so. All other indications are good, and I am reserving judgement until I get a chance to see it down at SL. The trip to Nolstein, and back, should give me a good idea of how it's performing. Only question mark now I guess would be the camshaft. Looks as if the process of micing (sp?) the valve travel may be beyond my capability, and I'm sure not interested in a teardown at 300 SMOH.
Ron
I think you will like the 52 pitch where you are but at lower altitude you won't be able to use full throttle. Here I operate out of a couple runways at 7000 ft, 8800 ft, 9100 ft and 9600 ft. with DAs about 3000 to 3500 above.
The 52 pitch on a 160 hp engine is great but to travel anywhere I like the 56. You can run full throttle above 5000 ft instead of having to pull off even more power to get a good cruise RPM.
I think you will like the 52 pitch where you are but at lower altitude you won't be able to use full throttle. Here I operate out of a couple runways at 7000 ft, 8800 ft, 9100 ft and 9600 ft. with DAs about 3000 to 3500 above.
The 52 pitch on a 160 hp engine is great but to travel anywhere I like the 56. You can run full throttle above 5000 ft instead of having to pull off even more power to get a good cruise RPM.
Ruidoso Ron
Registered User
Alto, NM
Cimarron, I have a 41" Borer, so I was primarily looking for cruise performance. Decided that the next time I go to AK, I'll ship the tires and prop ahead. On my 150 hp Cub hoping the 52" will give me decent cruise without hurting climb too much. Should knock a few hours off of the trip to Nolstein, and get my buddies to stop griping about me being so slow.
Ruidoso Ron
Registered User
Alto, NM
I think you are right, but I wasn't able to turn above 2450 in level flight before I repitched. Didn't want to spend all my cruise time at full throttle, and the climb was frightening here at SRR.
Cajun Joe
GONE WEST
LS86 or Hammond, LA
Where's my rems?
Hey Ruidoso get over it.
If you're at 8000 feet you're lucky to get 65%. Since you don't have a CS prop your RPM falls with the reduced HP. Man, you're embarassing me. Or, are you just clever enough to be trying to sucker folks into the "Cubology Seminar Tent" at Nolstein?
Cajun Joe
-------
4Blue
Hey Ruidoso get over it.
If you're at 8000 feet you're lucky to get 65%. Since you don't have a CS prop your RPM falls with the reduced HP. Man, you're embarassing me. Or, are you just clever enough to be trying to sucker folks into the "Cubology Seminar Tent" at Nolstein?
Cajun Joe
-------
4Blue
Ruidoso Ron
Registered User
Alto, NM
Well Joe, I know that the highest point in Louisiana is about 400' msl. Out here in the Rockies, when flying at a constant altitude above the peaks, you tend to get a compression factor (similar to ground effect). I don't have an MP gage, but if I did, I am sure I would see a resulting increase in manifold pressure as I cross each peak or ridge line. I have submitted this information to the FAA, and am sure they will incorporate it into future mountain flying courses. This might explain why I have better climb performance, the closer I fly to the mountains.
