In addition, on my pre-flight checklist, it has me starting the engine on the R tank, do the run up on the left and then switch back to the R tank. To me this is a lot of changing of the tanks prior to take off and is asking for trouble.
Agree with the "trouble" aspect. There is quite a quantity of fuel in the engine components / pipework. Certainly in an FI engine, it will run for maybe even 30s before failing. As such, as an instructor / if asked for advice, I would suggest that whichever tank you do your "run-ups" on do not change fuel selector now until at a safe height.
There was a fatal accident (PA28) in the UK in the last 2 years, and a forced landing by a well known VAF contributor, both caused by a change in fuel selection. In each case something in the fuel selection system broke (unknown to the pilot) leaving the fuel at off. In the PA28 case this got him to ~200' after takeoff before the engine failed.
My understanding is that the Vans fuel valve has to go via "Off" to change between L & R. A good reason why, if you need one, to fit a better valve
The Andair valves for RVs have no "Both" for reasons as stated above. However, if you position the valve (non detent) between L & R it will act as both. Not suggesting you use it, but it does mean that switching between L&R does not go via Off.
As an aside, I was taught and practice/teach/advise:
- Start on lowest quantity fuel tank
- Prior run-ups switch to other (higher) tank
- Use Fuel Pump for takeoff and until at a safe height (I am amazed how many do not use the Fuel Pump!)
- Swap Tanks / turn off Fuel Pump at a height where you have a good time to diagnose and setup for forced landing. NB if either fail, it may be some seconds before the engine fails - and may take some time to sort and get engine going again.
This ensures both tanks have been checked prior takeoff, and you takeoff on the higher quantity tank.