Here is some info
I see conflicting info on the average size that people end up drilling their main jets.
Where do I get parts like new locking washers, main jet washer, gaskets etc?
Also I know that this carb has the metal float.
Where does one get the new foam filled float and is this something I can just swap out without having problems?
There are a couple of threads on this. You see different oversize numbers because there are different engines and installations needing different jet tweaking. Even the same O-360 is different based on the accessories (pipes, ignition, airbox), condition & installation. A fast RV with a good air-box installation (no leaks), electronic ignition and "hot pipes" will almost always run lean in RVs, even with the richest carb or jet (nozzle) made.
Stock jets are not rich enough for most RV installation, even the Mooney "Nozzle Kit" (Jet) is too lean. That is why I suggest just drilling the stock jet. A Mooney nozzle kit is over $200. Don't waste your money on the jet kit.
Many RV'ers don't even know if they're running lean. Look at you plugs, if they are not grayish tan and more white, you're too lean. Do the 8K test I described below.
http://www.aa1car.com/library/reading_spark_plugs.jpg
TEST FIRST THAN DRILL (Iteration) - You have to know if and how lean you are. Have you done any in-flight lean test? May need to go up one may be two drill sizes, than re-test. If you need more, than go another size up. In general two no more than three drill size increase will work for most.
TEST
Go to 8,000 feet (DA), WOT, full rich, level flight let the speed stabilize, than lean and note EGT increase to peak, where EGT starts to drop again. YOU NEED AT LEAST 150F +/- 25F. 125F is too lean, and 175F is about right just starting to go on the too rich side. **
ITERATION
You might find that EGT rise is about 125F to peak. Based on that you may elect to keep it stock or oversize one drill # for your 1st iteration. If you are way to lean you might need 3 drill size numbers OVER the stock size. I suggest never increasing more than two steps at a time. There's no formula for it, just experimentation. However you right about #28 is too much. There are other reasons to be too lean, one piece venturi (manufacture quality and not installed properly) and induction leaks.
The method of drilling and details are in my other post on the topic. It's not rocket science, its a brass tube with a hole in it. Granted its a metered hole in a "metal straw" sitting in a bowl of fuel. Simple suction draws the fuel. The MAIN jet is the only control at full throttle and full rich mixture. It may seem crude, but it's so simple and works, it's elegant.
PARTS
As far as parts, I have posted them before. You can get them at most aircraft parts suppliers. Go through your local FBO, see if they have or order it. That's what I did. The FBO had them on the shelf. Aviall has these parts but they don't sell retail, commercial accounts only. Spruce A/C might have it. I doubt Precision will sell them to you direct, but give them a call. Not sure on the status of the new company taking over the Carb Parts line. There's also Kelly Aerospace; they make many STC parts for the MS Carbs.
parts to take the carb bowl and jet off and re-install with new parts
(6) 78-A97 Lock tabs ($3.42)
(1) 16-A31 Gasket ($5.73)
(1) 16-A30 nozzle gasket/lock tab ($4.73)
(1) 16-A42 Jet Tab ($3.38)
(1) 666-1002--F FLOAT KIT, LARGE MA ($184.86) (latest greatest composite float, comes with some above parts)
() List price.
(if you have a new carb the gasket can be reused. Some times the bowl tabs can be reused. I would not reuse the jet lock tab, simply because I don't want any metal parts floating around. The bowl lock tabs can be visually checked when the cowl is off. A single lose bowl screw is not supercritical. The bowl screws do tend to work lose since the air-box hangs off the bowl. If you have too tight seals with cowl/air box it can work on the bowl.)
"Also I know that this carb has the metal float. The SB trail shows originally they said to dump the metal float and go to the hollow plastic one, then they say dump the hollow plastic one and go with the metal one, now they say dump the metal one and go with the foam filled one."
Yes there have been several iterations. Metal is fine, just check it. The newest of new is or was a solid composite float made by Precision. With their getting out of the Carb Line who knows. As I said Kelly Aerospace has the old line of metal floats made by Faucet. They are still selling New Old Stock. Precision floats? I just don't know the status of the availability. IF you have metal stick with it. Check it for leaks, check the needle seat for wear and the hinge for wear. Unless you have a very old carb with original metal float or original composite float (which was a disaster) than use what you have. If you have true doubts than replace the float with the latest metal or composite float. There was also a two to one piece venturi. That one piece due to manufacturing error and poor installation can cause the carb to be lean. Check the SB and installation of you have one piece venturi. If you have two piece venturi and its not lose, keep it.
