New Rotax 670 Install

[Jake W 0]

Anders, 

What are you using to attach the muffler to the firewall there in the picture?

[Anders Stenhammar 22]

I used a fuel refilling hose. It's reinforced and very strong. I cut it in 1" pieces, drilled two holes in them and bolted one side to the firewall and one side to the mufflers clamp.

[Alaskaflyer 18]

Mr Lappos, I am also doing the 670 conversion to my Mark4. I did upgrade the brakes to Matco Master cylinders and duel caliper. The photo is my mod to the pedals to get the required leverage. Rotax Rick has shipped my engine and I will provide updated as I go along.

[Alaskaflyer 18]

Getting the fuel system ready for the 670. I decided to go with a Gascolator instead of the glass inline filters. All of the fuel lines will be changed out.

 

[Alaskaflyer 18]

Picked up the 670 Beast and got it hung on the plane. Bolted right up with no issues. It does have a thrust line towards the left. I didn't notice that when I pulled the 582 off. Now the fun begins. 

[Alaskaflyer 18]

My 670 exhaust manifold does not have any provision for an EGT probe. Anybody got any ideas?

[1avidflyer 1983]

There are two types of EGT thermocouples.  With the one style you just drill a 3/16" hole in the manifold and the thermocouple  is held in place with a hose clamp that the thermocouple has been fit into.  The other style screws into a fitting that is welded to the manifold.  As I remember, the distance from the piston skirt should be 100 MM to the thermocouple.

[Alaskaflyer 18]

I ended up welding 2 nuts on the manifold.  Now I can use the original EGT probes.

[Alaskaflyer 18]

I started the exhaust system install today. Mike Hair's exhaust fits perfect. The original muffler brackets on the right side lined up and will work. The left side will need a new bracket made. The Rave valves are in the way. I keep looking at the offset to the left, thrust line. It just looks like a lot. Does anybody know where the thrust line should be?

[Alaskaflyer 18]

The exhaust system is installed and looks really good. The left side muffler bracket fit great. 

[Allen Sutphin 705]

I talked to Dave Snell, engineer for Kitfox, about the thrust line on my Fox. He told me to just center the thrust line and then use rudder or a trim tab. It really messes things up in a full cowling when you offset the thrust line 4 or 5 degrees L or R depending on engine.

[Alaskaflyer 18]

Thanks for the reply Allen. My engine is offset about 3 degrees to the left. Offset is built into the engine mount. I'll quit worrying about it. Today I'm starting to work on the cooling system. Lots to do with that.

[Alaskaflyer 18]

Hey, the radiator just fits behind the cowling. It took a lot of adjusting, but I think there is clearance everywhere. I will be building the lower brackets tomorrow. 

[wypaul 448]

Looks nice, are you planning on rubber isolation mount to take care of the vibration?

[Alaskaflyer 18]

Wow! I finally got the brackets made and the radiator hung. It took some doing, now it all fits under the cowl. A much cleaner installation than hanging under the belly.

[ChrisBolkan 130]

That looks like it will be a real ripper! That's a lot of radiator, which I assume comes needing to get rid of a lot of heat, which I assume comes from a lot of horsepower. :-)

[Alaskaflyer 18]

I finally got my radiator hoses installed. It's full of antifreeze and no leaking,,, yet. Gear box lube and oil for the RV is in. Just waiting on a couple of fuel fittings to finish the engine install. I still have to do the lip on the lower cowling, and the Randy Moore gear legs. One thing that bit me in the wallet was the dead ELT. Corroded out, nothing $750 dollars can't cure! Well, it is the new fancy 460 millihertz one.

[Alaskaflyer 18]

I am going to install the new tailwheel today. I have an 8 inch Matco wide unit. I am not sure about the springs. I have a set of J3 cub springs that I will try to use. 3 leaf where the original on my Avid is only one leaf. Someday I will try to build a composite spring to save some weight.

[Alaskaflyer 18]

I did not get the tailwheel installed today. The Bolt going up into the fuselage is seized in place.  I tried to turn it with a nut from the bottom and just galled the threads up. I also tried my trusty air hammer to no effect. The bolt is too short for the 2 leaf spring. It has to come out. I soaked it with Croil and  will try again tomorrow. 

[1avidflyer 1983]

Worst case, maybe drilling it out.  

[Av8r_Sed 82]

Early Kitfoxes had the tailwheel bolt glued in with structural adhesive.  You might try moderate heat to try to loosen it if you think there may be glue.

[Alaskaflyer 18]

I finally got the bolt out. It was just rust seized in. Air Hammer, Croil, breaker bar, hole cut in fabric to get at it and plenty of cussing! It only took 2 days to remove it. I'll send a picture tomorrow.

[Allen Sutphin 705]

Glad you got it out. I've got the same problem except mine was welded in. Probably 3 days of cussing, 2 boxes of band-aides, and maybe!

[TJay 1041]

Glad you got it out. I've got the same problem except mine was welded in. Probably 3 days of cussing, 2 boxes of band-aides, and maybe!

HaHaI put a spot weld on mine before fabric hope some one cusses me out someday too.

[Alaskaflyer 18]

Here is the only rusty area on this Avid. I am surprised to see no way for water to drain out of this area. In cleaning the mold and Croil out, I saw that water would pool here. No wonder it's rusty!  There should be a drain hole there. I'm not sure how that can be done. Maybe a small hole thru the springs and U channel?