Spraying Continued

I’ve been on the fence about wanting to install a fuel flow sensor. Eric Newton found that he wasn’t able to get the required fuel flow when he had the sensor installed. I asked him for more details about that while we were at Oshkosh, and he said that when he took the sensor out he found that a little piece of debris was blocking the little paddlewheel that should normally be turning. This was a bit reassuring, since it’s certainly excusable that the sensor would not meet the flow requirements under those circumstances. I’d like to have the fuel flow information for engine diagnostic and fuel economy reasons, but it’s expensive. Since the gravity version (gold cube FT-90) is less commonly used, it’s harder to come by in a non-retail situation. The red cube is common in low-wing airplanes and is fairly easy to find. The new price of the red cube is about $150 vs $250 for the gold. This is why I was very excited to find a gold cube listed on eBay. I have a set of automatic searches saved, so that I’ll get an email whenever a listing pops up with certain search terms. This was one of those cases, and the seller had a low starting price. There were no other bids, so I was able to get the sensor and a short piece of fuel line (with reusable ends) for $25 shipped! It has certainly been one of the best bargains of the whole project, at least on a percentage basis.

Fuel Flow Sensor FT-90 Gold Cube

Fuel Flow Sensor FT90 Gold Cube


I used the iron to smooth out the runs from my previous spray attempt, and turned my attention to the spray gun to see if I could figure out why it wasn’t atomizing well. It turns out that there is a screw on the side that adjusts the amount of air available to the gun, and it was turned down too low. After a readjustment the spray was back to how I remembered from before.
Spraying Polybrush

Control Surfaces- the black plastic curtain blocks out much of the light, so lift it up when I’m there to spray.


I sprayed the first round of polybrush on everything, then took a break until later in the evening, when I came back and sprayed another coat. Another great bargain that I found recently was on an oil filter adapter. Bob delivered the engine with just the oil screen, and after lots of research and discussion with Bob I decided to go with a full flow filter instead. It seems that Bob prefers the screen for a couple of reasons. One is that he’s concerned that during situations of high oil pressure, such as right after engine start, the spring bypass might allow oil to bypass the filter completely, where the screen does not. Another concern was with the mess required for cutting open the filter and such during oil changes. The benefits of the oil filter seem to outweigh these concerns for me. The first is the diagnostic benefit of the oil filter. If the engine is having a problem with accellerated wear, it is likely to be visible in the oil filter. The second is in the improved filtration capabilities of the filter versus the screen. The final is the longer oil change interval of 50 hours instead of 25. I compared the cost and features of the various oil filter options, including the B&C angle version, the Casper Labs knock-off of the B&C, and the original lycoming straight adapter. While the angle versions make for less of a mess during the oil change, some folks have trouble with interference, especially in the case of having an Sd-8 standby alternator, as we do. One major design difference between the Lycoming adapter and the others is that the high-pressure bypass is located inside the adapter in the Lycoming version, and inside the filter in the other versions. I don’t know if there’s any functional difference between those two strategies, but one big application difference is the threads on the oil
filter. Since it would be quite problematic to install a non-relief filter on a non-relief adapter, the designers used a different thread configuration. The Lycoming adapter uses female threads, with male threads on the oil filter. The other adapters use male threads on the adapter and female threads on the filter. I didn’t realize this until I already had a K&N filter on hand with the female threads! I was able to get a great deal on this adapter, which included the gaskets and a spacer place that is not used with our engine.
Lycoming Oil Filter Adapter

Lycoming Oil Filter Adapter- note pressure relief plate/spring inside


The filter side of the oil filter adapter

The filter side of the oil filter adapter