What prop dia/pitch you using and what static rpm do you show.
I am fairly new working with a friends 172H with the 300D Cont. The prop is a McCauley / 1C172EM-76-53. I have recently checked the tach and it is very accurate at the upper rpm range. The static rpm is just 2165 and the TCDS says 2260 minimum.
We've removed and inspected the intake side of the engine and all looks fine with no restrictions or abnormalities. Have also pulled the exhaust system and inspected the inside, but again, all is well there. Mixture is RICH a low rpm, but is correct in the cruise/WOT range. Pulled the valve covers and measured the cam lobe lift to make sure the cam was not worn down. Oil analysis said there has not been any abnormal iron wear for quite some time.
SO, why the low static rpm? If I read the TCDS correctly, this prop model can be used with either a 52 or 53 pitch.. Should I be using the 52" prop?
Those with an O-300D, what prop dia/pitch are you using and what is your WOT static rpm????
Re: What prop dia/pitch you using and what static rpm do you show.
What are your leakage numbers ? Secondly, did you factor in temperature, altitude, humidity and those other things that affect your available power..Unless you had a tach that an engineer uses, you might have a problem there too..
Re: What prop dia/pitch you using and what static rpm do you show.
I had the post earlier about the Continental O300D problems. Our problem is we cannot reach redline in straight & level flight. Our static is within limits and we are running a 52" (Climb) prop. Be interested to know what you find out. We have also eliminated the things you mentioned.
Re: What prop dia/pitch you using and what static rpm do you show.
Compressions were all very good, bore scoped well, too. Used a Tru Tach II, very accurate for this purpose. Checked the carb throat/bore for anything out of line or shifted, all was tight and looked good. Engine runs very good, smooth, idles well but rich. Looked at everything that might limit air flow into or out of the engine, cam and lifters included.. checks out fine.
Re: What prop dia/pitch you using and what static rpm do you show.
Nathan
Do you recall what the valve travel was when you checked the cam and lifters. Ours was approx 7/16" measured on top of the valve. We are still suspecting a cam problem. Was yours close to that?
Re: What prop dia/pitch you using and what static rpm do you show.
Nathan
Thanks, Really was leaning toward the cam and/or lifters being the problem and now I'm even more inclined to think that way. Apparently we are both having pretty much the same problem and since both have about the same travel on the valves that seems to make sense. I have not been able to find anyone who can tell me what a "good" engine valve travel should be but I'm betting it is more than 7/16". We will continue to investigate and post anything new we learn. Hope you will do the same.
Re: What prop dia/pitch you using and what static rpm do you show.
I've never seen a cam where all the lobes were worn down this evenly. Usually starts with one or more lobes. Oil analysis have looked good, no high iron. Gonna live with it for now, until we come up with some kind of answer....sigh!
