HELP! O360 Running Too LEAN with "10-3878 Jet" in my Precision Carb.

[Stevejohnson7@gmail.com]

My RV7A was flown for it's 1st flight last Tuesday, June 17th.

The plane has the following:
Aero Sport 0360 A1A
Precision Carburetor with a "10-3878" Jet
One Light Speed Electronic ignition
One Slick Magneto
Hartzell Constant Speed Prop

Took off and flew to 3000 feet AGL and maintained:
24" Manifold Pressure
2,400 RPM
for 45 minutes

The engine had the following temps:
EGT
#1 - 1422
#2 - 1438
#3 - 1438
#4 - 1400

CHT
#1 349
#2 376
#3 401
#4 396
The engine also popped and back fired during the flight.

When taxied to a stop with RPM at 1000 and mixture pulled out to full lean the engine stopped without any RPM rise.

Does anyone have any ideas WHY the engine ran so lean?

[osxuser]

There are two different mixture settings on the Carb, the main jet (used during rpms in the 1300 range and up) and the idle jet (below said RPM). 1400 EGT's are a little on the lead side assuming your mixture control is hitting the full rich stop (Check that first) but not extremely so. Obviously also density altitude is a factor here, not indicated altitude.

Now your idle mixture is easy to adjust, there is a screw up by the top neck of the carb that has a rich/lean adjustment, turn it a turn to the rich side, and try it again. Just start it, bring it up to 1500 and let the engine warm, then 1000rpm and Idle Cut Off and see how the rise is. 50rpm rise is perfect.

Given that all these things are checked and adjusted, I'd look at the power enrichment setting on the Carb to see if it's kicking in too late, you'll need at the very least a Carb manual to do that, and probably someone who is familer with the carb wouldn't be bad to have.