MT 15" spinner clearance

Previously I measured and posted the distances from the spinner to the crank flange for the MT-12-B. The issue with the previous post was that I had assumed that the MT-12-B came with a 15" spinner to fit my showplanes cowl. Once I started to fit things I noticed that the diameters did not add up and the mistake was that the "default" when you order a 12-B prop is that it comes with a P-469-1 spinner. The correct part number for the 15" spinner is P-285-1-A. Also, because I special ordered mine as Matte Black, this is a no-stock item. :(

The difference is significant!


The new clearance measurement are inline with the trusty internet posts.
 

I have my starter ring gear off for the cowl fit/installation and I also took the spinner to cowl gap out of the mockup plate distance rather than putting spacers on the cowl. For my records here is my horrible hand writing tracking the crank flange to spinner distance. I may increase this gap to more than 1/8" but for now here is my mockup target number:

MT Prop Governor

Not much to see here, other than my prop governor stud length... I installed the MT prop governor that I bought off of Todd. I have to do some digging to check on the length of the prop governor studs that came on my Thunderbolt. I know people typically have to install longer studs here, but I really feel like I would like to shorten mine up a bit. The gears lines up just fine, and there are threads a couple of threads into the governor flange so there is no need for my washer stack to be on there but I had other things that I wanted to get done today without rabbit holing into a broken stud. So I loosely installed this for the time being and will come back to address it later. I probably should have left it off, but I am in the mode of getting things out of boxes and onto the plane so I can clean up my inventory a bit.



Speaking of cleaning up the inventory, I ordered a top mount governor cable bracket with my show planes cowling. This lined up just as advertised. I did have to remove the fuel injector line to route it through the bracket, but other than that, everything looks great.

MTV-12-B Dimensions

One of the weekend tasks is creating a jig for the cowl fit up to take the place of the prop and spinner. I read a while back on the reliable internet that the distance between the spinner plate and the hub flange was 40mm. I did not want fit my cowling based on some internet numbers so I waited for my prop to arrive so I could take the measurements myself.

The first measurement I made was to the aft spinner cap. This looked to be 1.9". At this point I was completely assuming that the spinner itself was going to end flush with the aft plate.


Going to the manual, you will see that this is not a good assumption. When you fit the spinner onto the assembly you see that the spinner extends beyond the aft plate. With the spinner installed, there is ~1.55" between the aft most part of the hub flange and the spinner. I would really like all these numbers to add up, but having triple checked my setup, 1.54" (39mm) is the number.