My Nexstar uses the "iso engine mount" or whatever; it's two rubber boots that go over the engine's mounting holes, then two plastic blocks go over the boots and get bolted to the engine mount. The white blocks are bulging out around the rubber boots, which at first I wasn't too concerned about, but then...

I can't get the muffler on the engine; the engine is mounted too far to the left 'drivers' side of the plane, so the muffler hits the outside of the engine compartment when I try to bolt it on - I need about 1/8 to 3/16" to get it to work.

Should I bag the iso-whatever engine mount and just use the metal brackets? I think I might be able to get things to line up better this way. Other option is to cut more off of the side of the engine compartment.

I thought the plane was made for this engine - OS 46AX

The iso mount seems like a great idea and less vibration if it works. I would try to keep it if it actually works.

It looks like you may have to trim the exhaust side cheek of the airplane to get the muffler to fit. I found a picture of a Nexstar with an OS engine for reference. looks like trimming has occured here to mount the engine.

I hope this helps....

Richard

I think the problem lies in the changes from the FX to the AX. There is plenty of 'cheek' cut away from the plane, and I'd have to remove some of the structural support in the corner of the engine compartment to make this thing fit (due mostly to the squared-off corner of the muffler).

I'm wondering if there is a gasket that can go between the muffler and the engine to give me 1/16" or something.

You can search Tower for a muffler extension. I've used them for this kind of situation. the other option is just to carve away some of the fuselage cheek. This is not a problem, just be sure to seal the bare wood with a little epoxy or something.

Yup, you could extend the exhaust, but cutting wood is cheaper. Here's a .46AX with it's muffler well buried in my mustang's fuse. Just cut away what I needed, beefed up what was left as I deemed necessary, and sheeted the hole over. No biggy. Yours will likely require much less cuttin'.

J

Fat Cat:

I have 10 NexStars, all with 46AX's. The only problem I have had is fitting that engine into the plane. #1 problem is to keep from breaking the fuel outlet off the needle valve assembly (the outlet to the carb). You have bend the needle valve back enough so that you can clear that outlet when tightening the screw. Otherwise, there should not be any problems. Here the link with all the info [link=http://www.rcplanetips.net/important_engine_mounting_inform.htm]How to Install a NexStar Engine[/link] I hve not "shaved" any wood to make those engines fit.

Happy Landings!

Had the same problem,shaved cheek,then discovered the engine mount was offset more than 3/8" to the left[driver side].

Nothing in the front of the plane seems to be lining up correctly, including the nosegear, etc. I wonder if my engine mount or something is misaligned.

I understand there is supposed to be some correction for the fact that the spinning engine wants to pull the plane to one side, but my engine mount is 5/8" clear on the passenger side and 1/8" clear on the drivers side (to the beveled corner of the firewall)...does that seem right?

I was able to drop the engine in fine, with the removal of one of the screws holding in the remote needle, but I would need a decent sized muffler extension to get the muffler to clear the side of the plane.

I'd have to remove a lot of wood if I was going to start cutting to get it to fit. Also, I could try to move the whole thing forward 1/4", which would get the engine to fit, but probably cause more misaligning of steering rod, throttle arm, etc.

I just called a LHS and he said that the engine mount should be pretty close to mounted in the center of the firewall; mine is over 1/2" offset. I thought this was to make up for the spinning of the engine, but there is also a bevel to the firewall, which maybe if the engine is mounted in the center the firewall would be sufficient to offset the spinning action?

You sure you don't have the engine mount upside down?

Wouldn't that be embarrassing...let me check... nope, it's not upside down.

Fat Kat:

Time to call Tower support! There is nothing left to adjust, short of carving. I promise you, shaving wood is NOT the answer!

Happy Landings!

Thanks. They don't know, but think that the fuselage may have been mismarked/misdrilled and told me to call Hobbico tomorrow.

Anyone have a Nexstar that could show a pic looking down at the engine to see where it's supposed to be mounted?

Here's a picture of how it should look from the Nexstar manual.

Ken

Yeah I don't know I have to call Hobbico. I removed the engine from the plane and went to see how it would fit without the rubber mounts, using the "alternate engine mounting method" and it was way worse; this thing wouldn't fit AT ALL if I didn't have the rubber boots. Something's wrong, and I bet it also accounted for the hours and hours it took me to manipulate the steering push arm to get the wheel to move to the right.

Thanks for that pic. I don't know if the engine mount is too low or too far over or what.

Here's one more....

I don't know what to say, I can't say mine looks any different from the pictures, but 1/8" difference would be hard to see, and maybe that's all it is.

Dunno (imagine a smiley guy scratching his head looking up)

Actually, a picture would go a long way to helping here. Looking at the picture that came out of the manual it's easy to see that the engine mount is offset to the left side of the engine compartment. So it's hard to imagine how yours can be much more offset from center.

Ken

That's what I mean, I can't see how there's a difference with the pic in the manual offset so far from center. Maybe my engine mount is lower or something.

If you remove the rubber boots from the engine itself, you should be able to sit the 'feet' on the grippy part of the engine mount, and strap it down with supplied metal straps and bolts. If you try this with my plane, it's even worse of a fit; the whole length of the muffler hits the side of the plane.



(baffled)

Look at the picture I posted. In the center of the engine mount you can see the hole in the firewall that the fuel tank sits in, and the fuel lines come through the firewall. Is your's in the same postion as the picture?? In the picture the hole is along the right side of the mount, and right under the top of the mount. If your mount was any lower than it's supposed to be then the top of your mount would be across the hole.

Ken

I think it's a tough angle they're showing there; the center of the hole in the firewall is lined up with the center of the hole in the engine mount, but the right sides of both holes are nearly tangential. I'd say mine looks pretty much the same as that picture.

so I did a little comparison since I got a second iso mount for my OS 46AX for my Gizmo kit build which works great on that plane as well as being inexpensive it does reduce vibration through the airframe.
the OS 46fxi and the AX engines are nearly identical other than the P-box is a little larger toward the outside of the exhaust flange the dimentions are the same for both engines.

I am planning to switch the engines since I am planning on mounting the AX in a Great Planes mustang kit I have,really there great engines the AX just has a little more umph to it.
the comparison pic is a little off angle, I did messure both engines and there nearly identical.

between the nose gear and the engine mount issue you might have a solid reason for a exchange of your fuse or the entire plane,the Nextar is a nice trainer,and has a good looking airframe,sometimes these ARF's don't get done corectly Tower is pretty good with problems

I think the rounded muffler might squeeze in, but I know plenty of people have mounted the AX in the plane without this problem. Will call Hobbico today.

Hobbico wants me to take everything out and mail the whole plane back; what a pain this whole thing has been. I have been online every night with some problem or another, am 90% done installing things, and now have to go back, remove everything, buy a box and shipping supplies, and pay for shipping back to Hobbico.

Argh.[:@]