Replies to This Discussion

Permalink Reply by Conor Whitehead on April 14, 2018 at 1:41pm

No idea about that particular prop Ralph.  
My plane came from the original owner/builder with a Catto three blade 68" x 36 pitch prop.  Works good for me.
I use this little site to look into prop settings.  http://culverprops.com/pitchselection.htm
Let us know how it goes.  Really seems like it depends on if you're optimizing for cruise, or STOL.
-Conor

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Permalink Reply by Robert Riat on June 24, 2018 at 4:52pm

Do you still have your prop set for climb?  I have a stol 750 with the 350is and a little over 20 hours into

my testing.  I set the prop (same as yours) in the middle (4) and the plane leaps off the runway, but It will

not cruise much over 90 mph without pushing it and raising my oil temp. I have a better oil cooler ordered

-- hoping to help on the high oil temp and plan to change the prop for more speed when finished testing.

Would appreciate any comments on the subject.

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Permalink Reply by Ralph Powell on June 25, 2018 at 6:41pm

Robert,
Pushing? The 350’s should run around 2800 rpm at a steady cruise. Pitch setting should not make much difference to oil temp at this rpm. I went for a 2 hour flight early today at 6500’, 27-2800rpm, OAT around 60 degrees. Oil temp did not exceed 212 degrees. Avereaged under 208 degrees. CHT’s did not go over 245 degrees. Prop is set mid range. CHT’s are critical. According to manual, UL allows oil temps os up to 248 degrees. This also happens to be the temp range where oil starts to break down. For more on oil google “Bob the Oil Guy.” He dispels many hanger myths and misinformation. I am flying the Cruzer so I cannot comment on your air speeds. If you want to discuss non-airspeed issues call me.
Ralph, 208-680-2561

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Permalink Reply by Robert Riat on June 25, 2018 at 8:59pm

Thanks for responding Ralph,
I am mostly curious what effect changing the prop to a faster cruise will do to climb out.
I am currently flying from our local airport with an asphalt runway (69k) but plan to move the
plane to my farm this Fall where I have 1500' of flat area to land in -- so I don't really need
to leap off the runway like the stol will do. I don't disagree with anything you said, but I'm
an "old school mechanic" -- had my own shop working my way through college in the early seventies
and numerous engine rebuilds (auto, motorcycle and diesel) my experience is that cooler is better.
At 2850rpm, AOT 80F, my engine is running 228 degrees (that was what I meant by pushing) and at
2600 it comes down to about 222. It is never at 208. Anyway, irregardless of what UL says I want
my oil temps down around 200 and Ray says the cooler he is sending me will do that and not much
change to my cowl. I will know before long.
I do like the engine, just hoping to get a little more trust in it. I'm pretty much a Lycoming
or Continental guy and when one of the banjo fittings failed (factory installed oil line to the
top of the head) at 19 hours and sprayed oil all over my firewall and underside of the fuselage
-- I wasn't thrilled. I will say that UL was quick to respond and the fix was easy. So it goes!
Thanks, Robert

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Permalink Reply by Ralph Powell on June 25, 2018 at 11:54pm

Robert,

Had banjo fitting on fuel filter develop drip type leak. No love for banjo fittings here. Find myself running a finger over all the fuel fittings checking for wetness whenever the cowl is open. Oil temps of 228 are enough to get a persons attention. I do not think you are the first to upgrade oil coolers. As to the engine, I fully enjoy the fuel injection and it is pretty! I do find adjusting tappets to be a pain. Had to buy a new set of feeler gauges, it has been years since I had to pull valves covers and play with rocker arms. Just about forgot how. Buy extra valve cover gaskets. They are easy to tear. I ordered  a couple of extras on regular stock order at bearings store, price was not to bad that way.

Prop settings are difficult to quantify. The heat build up at higher rpm was obvious. The steepness of climb out is harder to measure. With a flatter prop setting it seemed like I could “hang” on prop during climb out due to the higher rpms. The heat gain was such a loser for me that I changed pitch quickly. Also, cruise speed dropped enough to notice with flat pitch. 

Even with the  Cruzer, 1500’ would be enough runway most days. Some days I just find myself coming in high, fast, and long.

Enjoy flying!

Ralph

N750RP

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Permalink Reply by Ralph Powell on July 7, 2018 at 6:40pm

Robert,

Summer heat is finally here. With OAT in the 90’s  and oil temps pushing 120, I find that I am much more interested in the results of your oil cooler change-up. I would appreciate it if you publish your new oil temps and post a picture of your new oil cooler.

Took my wife out the other evening with temps still in the low 80’s and contrasting terrain, she did not appreciate the fun ride provided by the thermals.

Ralph

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Permalink Reply by Robert Riat on July 7, 2018 at 8:26pm

Ralph,

  I will be glad to do that and I have the new cooler, but have decided to wait until the 50 hour inspection.

Don't ask me why (because it makes no  difference), but my goal is to have my 40 hrs. of testing completed by July 19 -- that's the day I picked the kit up at the factory last year.  I told some of my

friends it would be a piece of cake getting it done.  WRONG.  Anyway, I am only flying it at sunrise

in cooler temps. and have 9 hours to go.

   Yeah, very few women like the bouncing around.  I live in KS and am flying to Oshkosh on Monday

in the Warrior, coming back the same day and I'm sure the ride home won't be fun......

Robert

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