In our RV-7 we have a O-360-A1A (carbureted and dual mags) with a constant speed Hartzell. Fuel flow in the climb has been 12-15 gph and in cruise at 4500 (e.g. 20.6 man, 2430 rpm, egt ~1470, ff 14.2). I have a new commute for work and it's only a 50 NM flight (hence the lower altitudes). There are some rocks to cross and altitudes I've tried range from 4500 to 7500. I'm able to get the fuel flow down around 9-10 at 7500, but I've also seen excursions to 12 and 13 gph.
Historically, I've been able to flight plan for 9-10 gph if I was in a hurry and ~7-8 if I'm pulled back. My leaning technique has been to set the power (20-23 man, 2000-2100 or 2300-2400) and pull the mixture back until the EGTs are in the 1450-1470 range (never exceeding 1500). CHTs are 350-375.
My engine monitor is a vision micro 1000 (fuel flow, 4 EGT, 4 CHT). In an effort to determine if the fuel flow sender or monitor was acting up, I filled the tanks to the brim, flew to work, noted the 4.3 gallon burn, topped the left tank up and noted 4.3 gallons on the pump. This suggests the fuel flow sender and engine monitor are not the problem.
There are no signs of blue fuel stains, the cockpit is not awash in fuel (no drips noted, no scent of fuel with boost on or off) and the interior of the cowling does not give an indication of a fuel leak.
I'm looking for some suggestions on next steps to track down the source of my higher consumption. The engine was overhauled more than twelve years ago, has ~800 hours on it, compressions are all in the mid-70s, condition inspection was five months ago and I've put ~50 hours on the aircraft since then.
Thanks for your help and suggestions.
(I do plan to put on at least one electronic ignition in the future once this issue is sorted.)
Jeff
Historically, I've been able to flight plan for 9-10 gph if I was in a hurry and ~7-8 if I'm pulled back. My leaning technique has been to set the power (20-23 man, 2000-2100 or 2300-2400) and pull the mixture back until the EGTs are in the 1450-1470 range (never exceeding 1500). CHTs are 350-375.
My engine monitor is a vision micro 1000 (fuel flow, 4 EGT, 4 CHT). In an effort to determine if the fuel flow sender or monitor was acting up, I filled the tanks to the brim, flew to work, noted the 4.3 gallon burn, topped the left tank up and noted 4.3 gallons on the pump. This suggests the fuel flow sender and engine monitor are not the problem.
There are no signs of blue fuel stains, the cockpit is not awash in fuel (no drips noted, no scent of fuel with boost on or off) and the interior of the cowling does not give an indication of a fuel leak.
I'm looking for some suggestions on next steps to track down the source of my higher consumption. The engine was overhauled more than twelve years ago, has ~800 hours on it, compressions are all in the mid-70s, condition inspection was five months ago and I've put ~50 hours on the aircraft since then.
Thanks for your help and suggestions.
(I do plan to put on at least one electronic ignition in the future once this issue is sorted.)
Jeff