I read a ton on here about this. It seems to get an US 40 to balance even close you need to get rid of the lead ingot engine mount. At least that's the general consensus. I bought a nice light Hayes "glass filled?" engine mount that is over 2oz lighter than the standard one. But the holes don't line up, and the mount is smaller, but just enough to get in the way of the old blind nuts. Is cutting an access hatch, and gluing in a new 1/4" plywood firewall in behind the original and adding new blind nuts like this: http://www.barnyard-buzzards.com/Bui...ck40/Page2.htm The best way to go? Would just moving my 3.2oz battery way back into the end of the tail work? Or moving the fuel tank just in front of the servos? I did a search but couldn't find any Flubber to use for tank padding.. I already bought 3" foam wheels for the front, but that only saves an oz, and I know it won't be close to enough. I just don't want to add lead to it. It's getting an Irvine .53 up front, so that might add nose weight also. How about a light engine mount that has a big enough "mounting plate" so that I could drill holes into it to match my blind nuts? This is my first ARF, ARF = Almost Ready to Friggin pull your hair out building. Thanks for any ideas. It took me 40 mins of searching to find out how to remove blind nuts, so I did read some before I asked. - Joe

Oh, and if I don't balance it. And leave it being tail heavy, what going to be ugly about it? Won't do flat spins? hmmm Why am I doing all this work to make it "Perfect"????? - Joe

JOE- I remove blind nuts by running a screw in about 1/8 in and rapping it on the head with a small hammer or hammer substitute. You want any airplane to balance correctly; noseheavy causes problems too. Try putting an OS .70 fourstroke on the front. That's what I had to balance; I wound up putting an 1100 mah battery pack as far back as I could; cut a hatch in the bottom of the fuselage. It was either that or add six oz of lead to the tail! ...JIM

I have replaced ARF engine mounts by doing the same thing, knocking out the blind nuts. To hold the new mount, I used the brass threaded inserts. Great Planes and DuBro, as I recall have them. You can fill the old holes with 1/8" dowel epoxied in. If your holes are going to overlap, you might want to angle the engine slightly to the side.

If you are using the square back Hayes mount, you can grind away the nose gear "hole" reinforcement and move the engine a little more to the rear.

In addition, after you mount your engine, take the rudder servo out and rubber band it right in front of the fin and check the balance. If this does it, you can cut a hole for the servo, CA a little piece of 1/16 ply under the balsa sheeting and hook it up pull-pull with coated fishing leader. I have attached a photo of my SK/50 that I made this mod on to balance when I used an OS .61 instead of the recommended .46.

Im confused, in your first post you talk about moving everything back (insisting that its nose heavy), in your second post you talk about leaving it tail heavy... which is it, nose or tail heavy?

A little nose heavy wont hurt anything, if its tail heavy you will want to try to get it as close as possible to the CG. If its too tail heavy it wont fly good at all... I have seen planes almost uncontrolable from being tail heavy.

Yes.

Cut a hole in the top rear sheeting and velcro your battery pack back there. CA some sticks in place to keep it from shifting, then cover the hole with a bit of matching Ultracote.

Bolt pattern for the GP .40 adjustable mount is a close match the bolt pattern of the H9 mount...

A battery all the way back as far as it will fit got my CG perfect. Test it by masking taping the battery on top of the rear fuse in different spots. That will tell you where you need it permanently.

Joe