too rich

[Cadstat]

After the 'tune up' my mechanic thinks we are still running rich. It's a IO-320C1A that started life in a twin Comanche as a turbo'd engine. Four owners later the turbo is gone. The injector's number is not a turbo injector. What else should we look at?

[Radomir]

What's too rich? Idle or in flight? It's best to collect engine data (ie EGTs, FF, etc) and then try to determine what rich/lean really means.. Without this data, it's a guessing game.

[John Clark]

As Radomir said, more information is needed. Also, at 4700 MSL, even with the injector functioning perfectly, you will have to lean virtually all the time and not see full rich until you get closer to sea level. Fuel flow numbers will tell the story.

John Clark ATP, CFI
FAAST Team Representative
EAA Flight Advisor
RV8 N18U "Sunshine"
KSBA

[RV10inOz]

Colorado.....hmmm will be TOO rich if you have a correct setup and use full rich setting.

At sea level you should see 16GPH at take off min15 anyway, assuming its a 160HP engine.

Easy test would be duck down to a 0-500' AMSL airport, Do a takeoff and note the fuel flow as you go through 300AGL as well as the EGT on say Cyl 1, any one will do or if signle point EGT, use that one and provided you are getting 15-16 USGPH that EGT number is the "TARGET EGT" you should lean to when departing your stratospheric abode.

Hope that helps.

[aerhed]

Easy test would be duck down to a 0-500' AMSL airport

That would take all day and $500 gas from Greeley CO.

[John Clark]

Originally Posted by aerhed

That would take all day and $500 gas from Greeley CO.

Or a litle time spent reading the Lycoming handbook for an IO-320 C1A.

John Clark ATP, CFI
FAAST Team Representative
EAA Flight Advisor
RV8 N18U "Sunshine"
KSBA

[Cadstat]

I have only the mechanic's thoughts to go by. I just had the mags over hauled. Plugs are only at 20 hours old and I got a new plug wire harness. The timing was off 3 degrees and mags run out at 750 hours before the tune up. The exhaust pipes are always black never the light gray. I have a new digital EGT but not fuel flow and a small CHT. I was burning 8.2 per hour @ 6-9K MSL cruise but only doing 165-170 MPH MAX and it was often difficult to stop the engine back on the ground even with the mixture full out at 4700 AGL. It didn't want to stop. Another engine Guru on the field is going to render an opinion soon.

The final unknown. The engine was originally turbo'd in the 1970's configuration. The fuel servo was modified in some way according to the stamp but I can't find the log entry to that effect. The fuel servo is $600-1200 to overhaul and I would rather buy a extra 1/2 gallon/HR than fix the servo that isn't giving me any other trouble. Any thoughts are appreciated.