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rawheels
01-05-2020, 08:02 PM
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/threads/10047-Model-IV-Smooth-Cowling-Help (includes my info)
https://teamkitfox.com/Forums/threads/5383-Smooth-cowl-Rotax-912-IV-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.
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* 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/threads/10274-IV-Smooth-Cowl-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/threads/4825-firewall-starter
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There is also another style shown in some pics on the first page of this post:
https://teamkitfox.com/Forums/threads/7999-Changing-out-a-912-80-HP-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/threads/7999-Changing-out-a-912-80-HP-in-a-model-IV/page3

rawheels
01-11-2020, 06:32 PM
Section F - Carburetor (steps complete)
* Step 6; Using the balance tube from Kitfox will eliminate the manifold pressure port. If you want to reuse the original tube, you'll need additional "ROTAX 956-142 LOW PRESSURE HOSE" for the ends.


Section G - Cooling System (steps compltete)
* You may need to adjust the coolant fittings. I needed to realign one bottom one, and swap a couple of the fittings on top of the cylinders. See more info starting on page 3 of Wheel's post:
https://teamkitfox.com/Forums/threads/7999-Changing-out-a-912-80-HP-in-a-model-IV/page3
* Step 3 reuses some of the hose from the original engine. If you are using a used engine you'll need to purchase some additional 17mm coolant hose. (or 16mm silicone heater hose works well too).
* Step 5-6 talk about installing the 41908.000 & 41909.000 coolant lines. They no longer come with the kit. You'll need to come up with your own solution, and/or purchase additional 1" coolant hose to connect between the engine and radiator.
* Step 15 (Figure G-7) indicates using 4x AN960-4 washers, but only 2 come with the kit.

jmodguy
01-11-2020, 07:36 PM
Showing good progress!

Shadowrider
01-12-2020, 02:58 PM
Will be a great mod for your aircraft. We have a 582 on a powered parachute and had two engine failures so far. The rave valves are not my favorite. Putting a 912 will be much better!

rawheels
05-27-2020, 07:18 PM
After section G, you might want to figure out where you are going to mount your coils & CDI boxes. It isn't in the instructions. Ref: https://teamkitfox.com/Forums/threads/10709-Model-IV-Smooth-Cowl-Coil-CDI-mounting

Section G – Oil System
The additional instruction pages include some pics of the oil cooler mount, but none of the them show the hoses, and the text was written without the cooler. You'll need some additional hose (and fire sleeve) to add the cooler into the system. A common place seems to be between the tank and oil pump inlet. You may also want to consider a oil temp bypass. The 90 deg fittings that came with the cooler didn’t not work for my application. Ended up needing a 60 deg for the inlet and 180 deg to the pump, but will be different for each system based on hose routing and if you use a bypass.

Section I – Throttle
* Step 1 & Fig I-1. Measure the throttle cable that came with your kit. Instructions say to drill a 3/4" hole. The current throttle cable (McFarlane) in the kit is only a 1/2" diameter.
* Step 5. Ref fig J-5. If you are installing a primer, you need to build your fuel valve with a different fitting (not included in the kit). In fact only 2-3 parts of the primer system are included. Kind of seems like they meant to delete it, but only got halfway done.

rawheels
08-10-2020, 09:36 AM
Section H – Oil System (steps complete)
* typo above, Section “H” is the oil system, not “G”.
* As mentioned, the original fittings for the oil cooler did not work, The 180 deg fitting I used was JEGS 110082, and the 60 deg fitting was Vibrant Performance 22608.

Section I – Throttle (steps complete)
* Steps 12-15. Attach the throttle cables to the carbs using the instructions that came with the throttle cable. I did not have to modify the control arms as described.
* Kit comes with parts to build the Kitfox “D-ring” choke cable that installs under the panel, but instructions were not provided with the kit. Debra at Kitfox Aircraft emailed those to me quickly when requested. Like others (https://teamkitfox.com/Forums/threads/10420-Model-4-choke-when-installing-a-912) I chose to purchase a McFarlane MCC101D048-RBC installed on the throttle quadrant plate, since mine already had three holes from the 582 install.

Section J – Fuel System (steps complete)
* Step 1. The header tank is not included in the kit. If you want to upgrade to the aluminum tank (recommended) you will need to purchase that separately. Also, the 90 deg fitting for the outlet of the header tank is not included in the kit (but should be already installed from the 582 install).
* Step 14 and figures J-4 & J-5. Obviously, omit steps if the primer system is not installed. As mentioned above, not all pieces of the primer install are included in the kit.

Section K – Exhaust System (steps complete)
* Perform step 8 before you complete 6 & 7. Also, before installing the final time, make sure to align and drill holes for your EGT probes.
* Step 6. Exhaust nut torque is currently 12 Nm / 106 in.lb per 2017 Maint Manual, 78-00-00 para 3.5 (updated 2010)
* Step 8. I used the suggestion of others in the group to use two nested pieces of PVC to find the hole location in the cowling. The 1.25” PVC fits into the tailpipe and holds the angle while you hot glue the smaller pipe to the base on the ground. You can slide it down out of the way. Remove the muffler, install the cowl, and then slide the PVC back up to mark the hole for the first cut. After everything is reinstalled you can mark for the 1/2'” clearance cut.
* Instructions do not talk about adding safety wire and RTV to springs, but highly recommended. Ref: https://teamkitfox.com/Forums/threads/10456-Exhaust-mounting-holes-are-getting-worn-on-a-912

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rawheels
08-10-2020, 10:23 AM
Section L – Electrical System (steps complete)
* This section is going to be very subjective to the instruments, avionics, and electrical components that you plan to use and those that have already been installed from the prior 582 installation. Plan on creating a custom electrical plan on your own. Figure L8 is a pretty decent wiring diagram when combined with the one in the Rotax install manual.

Section M – Propeller (steps complete)
* Instructions are written towards a GSC propeller, that doesn’t come in the kit. Install will be similar depending on which prop you have chosen. Follow your manufacturer’s instructions.

M is the last section of the manual. Still left to complete:


Cowling modifications, incl oil cooler inlet and top cowl molding issue. Section D above.
Windshield install
Glare shield fabrication and install
Fuel pump overflow line install

T.W. Sullivan
06-06-2023, 04:04 AM
Thanks for the Info. on firewall modifications to fit starter