When converted from 75 hp to 85 hp a new engine tag is supposed to be
placed
on the engine.  Have you checked this tag on the top right of the engine
case?
Jim
-----Original Message-----
From: Dennis Schmaltz <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED] <[EMAIL PROTECTED]>
Cc: [EMAIL PROTECTED] <[EMAIL PROTECTED]>
Date: Wednesday, March 03, 1999 10:11 AM
Subject: Re: Correct Prop


>Here's one for you.  I have (supposedly) a C75-12.  The prop on it,
>according to the tag from the prop shop that was in the paperworks says
>that the prop is a 1C90-LM7252.  What engine is this prop supposed to be
>on and what engine do I have?  I say this becaused I cann't find
>anything to indicate that my C75 was converted to a C85, but the dip
>stick has been remarked to indicate 4.5 quarts and the plane has a tach
>in it with markings for the 85 horse engine.  Makes me wonder.
>Dennis Schmaltz
>Mission, SD
>94715
>
>
>[EMAIL PROTECTED] wrote:
>>
>> Charlie,  If I remember correctly, for the 75 it should be a 73" dia.
>> with 71" perhaps being the minimum for repair.  The pitch is finer than
>> that of the 85 prop, so it should be 7351 (I think) for the 75.  If you
>> install a 85 HP prop on the 75, you "may" get the same performance as
the
>> 85.  85 props are 7150 std, and 7148 climb, with 69.5" being the min.
for
>> repair.   The shorter prop allows for the acheivement of the higher rpm
>> of the 85.  The 75 hp McCauley specs are in the Service Bulletins and
>> Memos.  The spec for the 85 hp McCauley prop are in the Univair
catalog.
>>
>> Speeds.  We used to fly 3 Ercoupes in loose formation with a Cessna 140
>> with 85 hp. The other two Ercoupes airspeed indicators read higher than
>> mine.  They said, "they cruised at 110."  My coupe, indicated 100 (110
>> WIDE OPEN LEVEL !)  was faster than theirs regardless of the indicated
>> airspeed.  And, alas, the Cessna with the same prop and engine could
>> steadily pull away from me when I was wide open.  My prop is a 7150
which
>> now measures at minimum diameter of 69.5".  I have had people tell me
>> their coupe cruises 110 and even 120 but it ain't so.  In the real
world,
>> and if their airspeed indicators were right, more like 100, 105, 109,
>> depending on model, engine, etc.
>>
>> Engine condition.  Prop.  Rigging.  Drag (mucho antennas, etc.) Getting
>> on the step. All of the above, and more, impact top speed and cruise
>> speed at a given rpm.  Oh, and the top of the canopy is a real source
of
>> drag.  Do you fly with yours cracked?  I have put a shade panel in mine
>> and the two side windows which used to meet at the top not just come up
>> to the edges of the shade window which is Smooth on top.  Really, a 75
>> ought to go just as fast as an 85 hp model, assuming both have engines
>> that are not "tired."
>>
>> Grover
>> 99398
>> Columbus, GA
>> On Thu, 25 Feb 1999 10:00:39 -0500 "Charlie Nightingale"
>> <[EMAIL PROTECTED]> writes:
>> >Need to know if anyone has the following:
>> >   1. What is the correct Mccaully  prop for a 75hp Ercoupe under
>> >cruise
>> >conditions.The numbers on mine have been overmarked and
>> >are not readily readable. It looks like CM 71.??. My speed is only
>> >about 98
>> >mph by GPS AT 2450.  I believe it is a CLIMB prop??
>> >Charlie N555CN  Farmville,VA.
>> >
>> >
>>
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