Carburetor air intake manifold

[taylorcraftbc65]

Re: Carburetor air intake manifold

I'll have to look to be sure about the prop, I'll get back to you tonight.

[Jim Meeker]

Re: Carburetor air intake manifold

Larry
When you mention the certified 75 modification per factory specifications, could you give me a reference for that document, I know you have to modify the carb and rods but I would like to see the specifics.

I have a McCauley CM74-45 metal prop. At full power I get about 2200 RPM(at altitude >5k drops to 2150) Now if my formula is right V(mph)= RPM*Pitch*.000947 this gives a theoretical max speed of 93.75 and I usually indicate low 90s. But if you reduce the pitch to 38 and 2300RPM doesn't this give 82.77mph as the theoretical max speed?
Perhaps I have the formula and/or math wrong. I realize that reducing the pitch will give more RPM, and I sure would like to climb better than I do now, but I would like to keep the cruise speed at least in the low 90s.

Thanks for all the great feed back
Cheers
Jim

[lktiller]

Re: Carburetor air intake manifold

Here's a link
Continental Engine Service Bulletin M47-16 (30 December, 1947, revised 9-25-68)

http://www.mooneymite.com/maintenance/serviceletters.htm

This next link has a more readable image but older revision.

http://www.sacskyranch.com/faqcontinental.htm

Attached to this msg is the parts list.

[lktiller]

Re: Carburetor air intake manifold

Jim, I remember formulas. That was the next row over from science. Right beside the shop class
The numbers I quoted previously were from simple observation on my long cross country flights. I haven't measured the prop myself.

There's always the tradeoff, climb vs cruise. That's why I like the 75 hp upgrade. Climb rate is increased by untwisting and shortening the prop. And by increasing RPM in cruise I have the speed in the 90's. Aggressive leaning keeps the fuel consumption down.

[Richard Boyer]

Re: Carburetor air intake manifold

I have found the perfect solution. I can get 1100lb of thrust out of this baby. So once I break free of the ground, point straight up for 30 seconds.......

Richard Boyer
N95791

(STC is pending)