Kevin, On my Coupe with the C-85, I had a prop twisted to 7146 and that got right at the maximum static rpm allowed by the relevant aircraft specifications A-718 and A-787 (you can read them from the links on my Coupe web page at: http://edburkhead.com/Ercoupe/index.htm
I'm thinking that the 7144 would probably give you a static rpm higher than the 2225 allowed. Because of that, you'd be out of spec and your AI could get in trouble if you blew your engine from over-revving in cruise (and it might spoil your day, too). I don't know if the prop shop can re-pitch it back to 7146 or not. As I recall, props usually can only be re-twisted twice (though successive twists in the same direction may not be a problem). A prop shop would have to look at the records and prop to tell you if it could be re-twisted. Personally, I liked the 7146 since it gave me better climb and I was OK with the resulting 100 mph cruise speed at 2400 rpm. I'd urge you to borrow a digital tachometer checker, find a VERY clean section of solid pavement (and sweep it) and do a full power run-up in calm conditions (or near calm and 90° to the wind). Find out what your full power static rpm IS. That's the governing criteria in the Aircraft Specifications. Ed Burkhead http://edburkhead.com/Ercoupe/index.htm East Peoria, Illinois ed -at- edbur???khead.??com (remove the ? marks and change -at- to @) -----Original Message----- From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of K Sent: Sunday, January 06, 2008 9:16 PM To: [email protected] Subject: [ercoupe-tech] Prop identification............. Got a few questions about my prop.....I think I already know the answers but I want a confirmation just to make sure. My prop markings are as follows : McCauley Corp. Design IA90 TC842 PC3 Serial# 7848 F7144 ... but the original stamp is F7148 the 8 has been overstamped with a 4. I'm going to assume the prop was originally a 71x48 and it has been re-pitched now making it a 71x44. Is this correct? If it's correct.......is the 71x44 prop appropriate for a 1946 Ercoupe with a C85 engine? Thanks, Kevin
