Model IV - 582 to 912 conversion

[rawheels]

I’m changing my Model IV from a 582 with a round cowl to a 912 with a smooth cowl (with a momentary trial of an HKS). I purchased an install kit from Kitfox Aircraft, but have had many issues with the install. I’ve found previous threads on this site regarding the individual issues that have come up and lots of helpful info. I’d like to use this thread to note items I feel would be helpful to those who decide to make the same change and to direct them to the info they will need within this forum. In addition, it might be helpful to those who are trying to get a good idea of what to expect if they decide to make this upgrade as well.

NOTE: this thread is not intended to be a bash against the Kitfox Kit. I really really appreciate that John and Debra still sell items for the model IV. However, I might suggest to them that when someone asks if the kit contains everything needed for the install that they may want to indicate that it will take quite a bit of materials and mods and not just say “you’ll need a new windshield too”.

Here are my notes:

Section A – Introduction (no notes)

Section B – Engine Mount (steps complete)

* Steps 10-11 describe installing the engine adapters to the doughnut bushings. You will need to have the hardware removed from the adapters in order to accomplish this. It took me an extra set of helping hands and a few tries to get it all together and attached to the engine. It also required 4 extra AN960-616 washers. The AN380 nuts would bottom out on the AN6-31 bolts without all three installed on each post as shown in Figure B5, but the kit did not come with enough to accomplish that.

Section C – Round Cowl (N/A)
Section D – Smooth Cowl (not complete)

Lots and lots of issues with these cowls. Safe to say you will be buying fiberglass materials and custom modifying them to fit. See these links for more info:
https://teamkitfox.com/Forums/thread...h-Cowling-Help (includes my info)
https://teamkitfox.com/Forums/thread...-1200-fit-HELP!

* You will end up trimming off 5"+ from the back end. That puts the prop flange in the right spot, but seems odd to have to trim off that much and it does cut through where the scribe line indicates that a NACA vent supposed to go. Just measure 20 times, cutting a little bit each time.
* The top cowl doesn't fit onto the bottom cowl at the front around the inlets. The material is too thick. I ended up sanding down the thickness to fit. Still isn’t perfect, but I think it will be fine for me.
* I did end up trimming off about an inch off the bottom of the top cowl in order for the prop opening and spinner diameter to be circular (8.5”, I believe). I cut off the bottom of the cowl where the finish seems rough (mold edge line?). Others warned me not to (after I had already done it). So far it doesn’t seem to have messed anything up. And, in fact I don’t think I will have to do any fiberglass at the front of the cowl like others have had to. The cut might account for some of that as the top cowl angles forward and gets into the prop flange area. Trimming it shorter reduced the amount mine angled forward. Will post more when I get back to the cowl, as I think it will show up most when I remake the glare shield. One note is that you will need to leave the two spots at the cowl inlet a little longer than the sides. I cut the same amount off of all surfaces and there is a larger gap at the overlap at those two spots.
IMG_0030a.jpg
* It took a lot of pressure to bend the top cowl down the sides of the aircraft with my original glare shield. I removed it and plan on fitting a new one when I install the new windshield. Without the glare shield my cowl fits much easier.
* Instructions say to use camlocks p/n 92000/92005/92015, but my kit came with p/n 98010/98011. The new ones are actually adjustable, so a bit of an upgrade. The instructions say to use qty 28 and only 27 come with the kit. I ended up only needing 26.
* Figure D-1, pg 21 shows 3x 91204 nutplates (and assoc hardware) being used, but only 2 sets came as part of the kit. Haven’t installed or worked on this part yet.
* You will need to custom make something for your oil cooler inlet. You will cut away a big hole in the front of the lower cowl (if you use the supplied mount). See the links to other posts above for more info and I will post whatever I end up doing about it.
* Don’t miss the note below step 8. You will need to temporarily place a simulated firewall piece in place to ensure your camlocks miss it. I missed the note, and noticed that mine are very close after install, but luckily they do not interfere. Thought “they really should put a warning in the manual” <facepalm>.

Section E – Firewall (steps complete)

* At step 8 you’ll want to check the fit of your oil tank. Even making the box as large as possible, my tank barely fit and touched the back of the engine. I had my tank modified, and am very happy with the fit now. See this link:
https://teamkitfox.com/Forums/thread...-Oil-Tank-Mods

* At some point after Kitfox designed this install, Rotax made the starter bigger. The new design will interfere with your newly created firewall. You will need to custom fabricate a piece to provide clearance. I chose to do something similar to Mr Bill & Geowitz in the post here:
https://teamkitfox.com/Forums/thread...rewall-starter
IMG_0056a.jpg IMG_0058a.jpg IMG_0062a.jpg
There is also another style shown in some pics on the first page of this post:
https://teamkitfox.com/Forums/thread...-in-a-model-IV

Section F – Carburetor (not complete)
(At the final step [6], no notes yet)

Section G – Cooling System (just starting)

* You may need to adjust the coolant fittings. See more starting on page 3 of this post:
https://teamkitfox.com/Forums/thread...model-IV/page3