Sunday, November 20, 2016

The 9A is running again

Not much 10 work to report this week since I think I spent most of the time working on getting the 9A back in running condition...that and I was traveling for the first 3 days of the week.  However, I did get my fuel servo back from AirFlow Performance this week and unfortunately he told me that it was running on the lean side of the calibration curve.  Well that leaves only the air inlet as a potential source of over rich fuel.  The theory that was presented is that my intake is causing some turbulent air flow at the inlet of my fuel servo which is causing it to indicate a much richer mixture is needed.  So I am going to be doing a few things to my inlet to see if I can eliminate that issue but first I am going to fly it with a few simple mods to see if it really is an issue with the air inlet.  Hence this weeks pictures.

I also took the time while the 9A was down to do a bunch of little things to the airplane.  I had a flat tire on the pilot side so while I had that wheel off to replace the tube I decided it was time to replace the brake pads on both sides.  I also spent a lot of time sealing up some of the small holes I found in my baffles that were hard to see with all the inlet ducting installed.  As an oddity I also took a file to the cooling fins between the valve guides...its one area where the casting process can leave a lot of "slag" and that also can affect cooling.


First up I decided to take a picture of the air inlet to my oil cooler.  I am going to have to do some work on this some day as well as I think I can make the airflow much smoother into the cooler with should help with cooling.

Next up you can barely see it here but on the left side of the picture you can see my new inlet ducting with the alternate air filer installed.  Look at the next picture and it might make more sense.

Here is a better view of the new inlet ducting.  This is the first configuration I tried and when I attempted to install the lower cowling I found that there is no way to make the alternate air duct fit inside on this side.  However, Jeff or Harry suggested I might be able to make it work if I removed my alternator and installed one on the vacuum pad on the aft end of the engine.

In this picture you can see the narrow channel that the air ducting has to fit in.

So here it is with the alternator removed and the new inlet ducting installed.  Works perfectly!!  However, now I have to buy a new alternator.  I guess that's ok because I need one for the 10 anyway.  One thing to note on this view is the huge gap between the new inlet duct and the cowling inlet bung.  I am going to have to fabricate a reducer that is about 3" long to bridge that gap.

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