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To:  lml@lancaironline.net
Date: Tue, 03 Feb 2009 15:57:22 -0500
Message-ID: <redirect-3474876@logan.com>
From: Lorn H Olsen <lorn@dynacomm.us>
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Subject: Re: cylinder wear-to lean or not too lean
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When I had my engine torn down for a prop strike at 700 hours, the  
engine shop pointed out pretty worn exhaust valve guides. They said  
that the guides wouldn't make 2,000 hours. I had them replaced. I now  
have over 1,500 hours on the same engine and it is running fine.

The engine shop and I have always argued about how lean to run the   
mixture. They like richer. I run as lean as possible. Flying locally,  
I usually fly at about 2,350 rpm and 22-23 inches of manifold pressure  
and as lean of peak as possible. More usually, I fly high (15,000 ft)  
running 2,350 rpm and lean of peak. That gives me about 1,420 EGT and  
22-27 l/hr (6.0-7.0 gal/hr). At all altitudes above 5,000 ft, I fly at  
full throttle. Unless racing, I never fly above 30 l/hr (8.0 gal/hr)  
as that is my 75% power point. At 5,500 ft at 30 l/hr (8.0 gal/hr), I  
run at 195 kts.

Last month, I was flying at 15,500 ft at my usual 2,350 rpm and lean  
of peak at 22 l/hr (5.8 gal/hr) at 170 ktas (130 kias). I then tried  
winding it up to 2,650 rpm and enriched to 28.4 l/hr (7.5 gal/hr). My  
speed went up to 185 ktas (145 kias). Even after flying this plane for  
10 years, I was amazed at the speed at which this carburated, mag  
powered 160 hp aircraft could travel.

Only time will tell about the leaning. I fly consistently and can only  
hope that I will get to and past 2,000 hr TBO.

Lorn

> From: gerardoconnell@optusnet.com.au
> Date: February 2, 2009 12:11:44 PM GMT-05:00
>
> just burnt out the exhaust valves on 1 and 3 (got 900 hours on my  
> 0-320)
>
> the shop reckons I'm running it too lean. I had an EDM 700 installed  
> last year and follow the directions for best power-usually gives EGT  
> 1450-1500 and 31-32 Litres per hour
>
> what say y'all
>
> Gerard
--
Lorn H. 'Feathers' Olsen, MAA, ASMEL, ASES, Comm, Inst
DynaComm, Corp., 248-345-0500, mailto:lorn@dynacomm.us
LNC2, FB90/92, O-320-D1F, 1,515 hrs, N31161, Y47, SE Michigan