The continuing V8 SR Saga
Posted: Sun Feb 19, 2012 11:16 am
Hope I'm not boring too many of you but I thought I'd keep everyone up to
date on my progress. Especially since I keep getting such great ideas and
comments.
58 degrees outside this morning, in October, and here I am stuck at work! I
don't think I mentioned it before but on the day of my first flight my prop
controls weren't working. But the prop was at fine pitch and I decided to
go anyway. Pretty stupid now that I know how bad a prop with too fine a
pitch can be. A little ignorance can get you into a world of trouble.
Anyway, I think I finally figured out what was wrong. The wires that
control the prop connect to brushes with crimp on paddle connectors. For
some reason, the connectors I was able to get locally fit quite loosely.
For that reason I added solder to the connectors then ground them down until
they fit tightly. Unfortunately, the solder fell off on one connector. I
knew I couldn't trust them to stay put so I slathered silicon around them to
keep them in place. I must have used the wrong kind of silicon because it
never hardened up. But the connectors were still in place. Why didn't the
prop work? I pulled the connectors out and cleaned off all of the silicon.
While fiddling with them one of the connectors broke off with very little
pressure applied. I wonder if applying the solder heat treated the metal
and made it brittle. Perhaps it was ready to break already and wasn't
making a good connection. I'm going to try to find new connectors that fit
better today. Then I'll apply Household GOOP which I've used before for
stuff like this. I know it will harden up and stay put.
I cleaned off the spark plugs and ran the engine again yesterday. I was
able to get it started easier but it still seemed like it was loading up,
running too rich, even when I leaned until I got an RPM reduction and EGT
increase. Could be my imagination but I'm going to fiddle with things a bit
more. I may get new spark plugs one number hotter.
My calculations for compression ratio comes out to 9.7 to 1. I wonder if I
should be running higher octane fuel? I am using regular unleaded right
now. I don't know much about how much compression ratio is too much for
regular unleaded. I don't detect any detonation or pre-ignition. No
knocking at low RPM or during my first flight running high power settings.
Despite high EGT the engine seemed to be running smooth as silk.
I had to re-read Ken's note about high EGT with a too rich mixture since
it's contrary to what usually happens with mixture and EGT. Normally, as
you lean, EGT rises, and as you enrichen, EGT decreases. But I hadn't
thought about the condition Ken describes about an excessively rich mixture
causing unburned fuel (not burned in the combustion chamber) to continue
burning in the exhaust increasing EGT. That does seem like a reasonable
possibility.
The engine quitting on the landing roll-out was definitely my throttle stop.
I was able to reproduce it. Simple fix.
Mike
044SR
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date on my progress. Especially since I keep getting such great ideas and
comments.
58 degrees outside this morning, in October, and here I am stuck at work! I
don't think I mentioned it before but on the day of my first flight my prop
controls weren't working. But the prop was at fine pitch and I decided to
go anyway. Pretty stupid now that I know how bad a prop with too fine a
pitch can be. A little ignorance can get you into a world of trouble.
Anyway, I think I finally figured out what was wrong. The wires that
control the prop connect to brushes with crimp on paddle connectors. For
some reason, the connectors I was able to get locally fit quite loosely.
For that reason I added solder to the connectors then ground them down until
they fit tightly. Unfortunately, the solder fell off on one connector. I
knew I couldn't trust them to stay put so I slathered silicon around them to
keep them in place. I must have used the wrong kind of silicon because it
never hardened up. But the connectors were still in place. Why didn't the
prop work? I pulled the connectors out and cleaned off all of the silicon.
While fiddling with them one of the connectors broke off with very little
pressure applied. I wonder if applying the solder heat treated the metal
and made it brittle. Perhaps it was ready to break already and wasn't
making a good connection. I'm going to try to find new connectors that fit
better today. Then I'll apply Household GOOP which I've used before for
stuff like this. I know it will harden up and stay put.
I cleaned off the spark plugs and ran the engine again yesterday. I was
able to get it started easier but it still seemed like it was loading up,
running too rich, even when I leaned until I got an RPM reduction and EGT
increase. Could be my imagination but I'm going to fiddle with things a bit
more. I may get new spark plugs one number hotter.
My calculations for compression ratio comes out to 9.7 to 1. I wonder if I
should be running higher octane fuel? I am using regular unleaded right
now. I don't know much about how much compression ratio is too much for
regular unleaded. I don't detect any detonation or pre-ignition. No
knocking at low RPM or during my first flight running high power settings.
Despite high EGT the engine seemed to be running smooth as silk.
I had to re-read Ken's note about high EGT with a too rich mixture since
it's contrary to what usually happens with mixture and EGT. Normally, as
you lean, EGT rises, and as you enrichen, EGT decreases. But I hadn't
thought about the condition Ken describes about an excessively rich mixture
causing unburned fuel (not burned in the combustion chamber) to continue
burning in the exhaust increasing EGT. That does seem like a reasonable
possibility.
The engine quitting on the landing roll-out was definitely my throttle stop.
I was able to reproduce it. Simple fix.
Mike
044SR
-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
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