Originally Posted by
carl24bpool
even if I wanted to lower the tank it would not be possible as there is just nowhere for a new bung hole. Even if I fill the old one and reinforce the firewall.
Yup, and that is one reason I dislike the "lower the tank" advice given so easily.
If you can do it, by all means DO SO. If it means having to cut joiners or formers, or making any sort of modifications to the plane... then DON'T DO IT.
As you've seen you will have to worry about your starting proceedure, particularly until the engine is properly tuned.
One of the problems that often occurs is the engine will have the needles set way too rich from the factory ( I've seen Saito's a good 8-11 turns OUT and yet the engines run this way!!! ).
Having the needles so far out lets the fuel drip into the carb and the head rather quickly.
However once the engine is tuned to run correctly, when it is close to an idle throttle setting, the siphoning is VERY slow. No more than a drop a minute or so.
You should then keep the throttle closed after you fuel the plane. You should NOT prime an engine mounted inverted particularly if there is a height difference, and you may want to set the LS needle just a click leaner at idle to make sure the engine does not bog down due to the inverted head ( not because of siphoning ).
Hint: Pull the glow ignitor off with the engine at idle. If the engine speed remains the same you have the LS needle set very well. Otherwise adjust until there is almost no change.
Originally Posted by
carl24bpool
Would it be acceptable for a centre line to be lower than spray bar then? Surely the muffler produces enough pressure to push the fuel through?
Sure. Note however that some mufflers, particularly Pitts mufflers may have too large exit ports to maintain enough of a pressure differential.
You can test this by plugging one side of a dual port/tube Pitts muffler... if the engine idles better this way, then you may want to add a bit of restriction to both ports... this is rarely needed though.
Originally Posted by
carl24bpool
As fas as my pc-9 goes I got it in the air. I had to fuel up, keep e throttle at closed off and right before starting I set to idle. I also removed the plug to check it was dry. It actually started quite easily to be honest. It did cut in the air and I had to dead stick. Wow these planes come in fast.
Check the idle, it could be loading up in the air. Use the "pull the ignitor" trick.
Originally Posted by
carl24bpool
I think the centre line alignment won't do any harm to follow as a rule but if it's so important surely he manufacturers would factor this into the designs and plans.
Correct.
Good luck with your plane.