Propeller EXPERIENCE

[Jim Herpst]

Why not a 75/38? approved for the c-150 seaplane...

Sorry I am not following you. I own a McCauley 1B90 74 currently pitched to 47. I am not going to purchase another prop

[astjp2]

If someone doesnt have one, look at the 75/38

[Jim Herpst]

If someone doesnt have one, look at the 75/38

??

[3Dreaming]

??

I don't think his second comment was necessarily meant for you, but anyone who in the future comes to the sight searching for the same information. Now it is recorded in the thread for posterity.

[Jim Herpst]

Ok

[Ragwing nut]

38 pitch WAYYYY to flat.

[Kerbs]

I went through the conversion to an C-85-12 on a short mount, marvel carb & no electrical, about a year and a half ago. It sounds like you have a good idea what is involved. I ended up selling my 74/42 I had on the 65 and purchasing a zero time 71/43 for the same price. I was unsuccessful getting Terry or anyone else to approve running the 74/42 on the C-85 based on the TCDS. The 71/43 is rated as a float plane prop but works perfectly well for my applications. I cruise in the 96-98mph range turning 2,400 with 8.50's.

[Jim Herpst]

Hmm. First was your a McCauley? Mine is. 1b90 clip top 74 currently pitched to a 47. I am going to start out with running the C75 as is (again it is a C not to be confused with an A). The prop is on the McCauley chart for a C75 . I will need to see about Terry approving it for the C75 on the Taylorcraft I will upgrade the engine later to a C85.

[Kerbs]

Yes, both were 1B90's. I actually first bought a 1B90 71/47 that for the C85 and it was way to much pitch. My cruise was 117ish at 2,400. I sold it and bought the 1B90 71/43 which was about perfect. (The 74/42 was a 1B90 as well.) I went with the 71/43 after taking to the museum on our field that had a locally famous Tcraft on floats and that is what they ran on it with a C85. I found it on a cub forum when I was looking. I'd say first look into whether you can get a C75 approved. From what I understand that's likely the harder issue. If Terry can hep with that, then I don't see why you can run it on the C75, but you may run into the same issue if you "up" it to a C85. I'm not a DER so maybe there are some ways to do it. I found when I did mine the most economical way was to hunt for a good C85 which took me a bit. Once I found that, I ended up doing everything firewall forward. Jim, PM me if you want to, I have an excel sheet of the cost for everything from my conversion that I am happy to share or help in any way I can. I sure learned a lot doing it. Or anyone else that is interested if they would like the run down info. I didn't view the prop as a big issue being I could sell my 74" to pay for a 71" that met the TCDS. I am also running the Luscome exhaust which I have been happy with. Also look into the cost of a repitch. I repitched my 74 from a 45 to a 42 and it ran about $400. They can only be pitched so many times and inches so it may economically make more sense to just get a prop that is good to go from the onset.

[Jim Herpst]

Kerbs,

Thank you. Yes I have spoken to Terry and he felt we could do a deviation of the short mount C85 with the C75. (I am doing this for the wife that said she does not want me hand propping anymore so no electrical but a lightweight starter with a battery I will charge when needed).The prop also I believe will pass as it is approved for that engine by McCauley but will need to nail that down for T craft approval. I will start off with it as a1b90 74/47 which may well be about like a 65 however the odd thing about a C75 is that the rates rpm is 2275 .Funny s it is an identical engine of the C85 sans for the carb venturi and the jet..The a&p gent I purchased it through said he flew behind it on a Cub the owner had it on as he would tow him in his glider with it. He said he was surprised how well it pulled. Yes we can and will pm each other, but wht did you do with your Gasculator with use of the luscombe 8e exhaust as I will be using that as well?

[Kerbs]

I purchased a new gascolator, I can't remember off hand which is was but I can look in my logs. We ended up relocating it to the firewall very close to where it was previously and then fashioning new fuel lines tot he carb. Access for checking for contamination works about as well as it did before, just a big more a reach but no big deal.

[dlinsley]

We have a 1B90 74/40 on a 100hp BC12D, we also have the same prop on a 65hp bc12d. It’s a great climb prop with the 100hp and appears to be a pretty good cruise prop so far on the 65 (one flight at this point)

[Jim Herpst]

A little surprised that pitch on the 65 is not little flat for it. Interesting.