Michael Burbidge
Well Known Member
Yesterday I started my engine for the first time. I have an Lycoming O320-D3G (160 HP) carbureted engine. My A&P timed the mags on friday, so I know they are set correctly.
I have a new (shipped to me Feb 2013) 3 blade Catto Prop. Here's the specs on the prop:
3-Bladed Glass/Carbon Composite Propeller for RV-9A
68" Diameter x 70" Pitch
O320-D3G 160HP@2700RPM
Top Speed at Target RPM- 189-193mph@2750rpm
4.375" Finished Propeller Thickness
7" Diameter Prop Flange
SAE-2 Pattern, 7/16" Bolts and 5/8" Lugs
Color: WHITE W/ RV-14 Blue Crescent Tips
I have an analog tachometer, so I can't see exactly what the RPM is, but it is hovering just a hair under 2000 RPM. This seems low. I was expecting more like 2100 - 2200.
I've searched the forums and there's is lots of information on static RPM, but the solution always seems to be re-pitch the prop. But according to what I've read and the specs that Catto sent to me, it appears to be pitched about right.
What I'm looking for is the diagnostics steps that you would take and what order you would take them in to determine if the problem is something other than the prop.
Here are some things that I can think of, and the order I will probably take in diagnosing this problem. Also a question or two for each one.
1) Throttle travel is not adjusted correctly. How's the best way to determine if the throttle is full open when the throttle control is full forward. I have a manifold pressure gauge. Can that help in determining if I'm developing full power?
2) My tachometer is not accurate. How can you verify the tachometer reading?
3) My FAB scoop opening is smaller in area than the carburetor throat. Just a thought. I have no idea, if you build to plans how much head room there is here. My intention was to build to plans. I can test this theory by removing the FAB and checking the static RPM. I have not installed the alternate air yet, or it would be easy to just pull the alternate air.
Are there other things that could be wrong other than the prop?
Thanks for any help,
Michael-
I have a new (shipped to me Feb 2013) 3 blade Catto Prop. Here's the specs on the prop:
3-Bladed Glass/Carbon Composite Propeller for RV-9A
68" Diameter x 70" Pitch
O320-D3G 160HP@2700RPM
Top Speed at Target RPM- 189-193mph@2750rpm
4.375" Finished Propeller Thickness
7" Diameter Prop Flange
SAE-2 Pattern, 7/16" Bolts and 5/8" Lugs
Color: WHITE W/ RV-14 Blue Crescent Tips
I have an analog tachometer, so I can't see exactly what the RPM is, but it is hovering just a hair under 2000 RPM. This seems low. I was expecting more like 2100 - 2200.
I've searched the forums and there's is lots of information on static RPM, but the solution always seems to be re-pitch the prop. But according to what I've read and the specs that Catto sent to me, it appears to be pitched about right.
What I'm looking for is the diagnostics steps that you would take and what order you would take them in to determine if the problem is something other than the prop.
Here are some things that I can think of, and the order I will probably take in diagnosing this problem. Also a question or two for each one.
1) Throttle travel is not adjusted correctly. How's the best way to determine if the throttle is full open when the throttle control is full forward. I have a manifold pressure gauge. Can that help in determining if I'm developing full power?
2) My tachometer is not accurate. How can you verify the tachometer reading?
3) My FAB scoop opening is smaller in area than the carburetor throat. Just a thought. I have no idea, if you build to plans how much head room there is here. My intention was to build to plans. I can test this theory by removing the FAB and checking the static RPM. I have not installed the alternate air yet, or it would be easy to just pull the alternate air.
Are there other things that could be wrong other than the prop?
Thanks for any help,
Michael-