I am building 2 sig kougers with 2 different engines,they are set at 45 degree angle.how would be the best way to find the proper location to mount to the fire wall and be in the center of thecowl? I have one mounted after much trial and error and putting the blind nuts in the wrong place,there has to be a better way.... HELP!!!!!

There should be a mark on the firewall a cross....or the plans will have a cross...this is the thrust line and off set.....the intersection of the cross should be dead center on the back of the engine.....or you can do some measuring like you're mounting the engine straight and just turn everything 45 deg

I am a big fan of the Dave Brown round back engine mounts:

http://www3.towerhobbies.com/cgi-bin...?&I=LXB872&P=7


Tend to use these on most everything. Notice the uneven hole pattern, this is to allow access along the sides of most two stroke glow engines from the front with a long tool. This is extremely helpful when the airplane has fixed cowl cheeks or tubs with any mounting orientation. The round back will allow fitting in many tight cowls where the humungous square adjustable types are just hopeless.

Now the technique I prefer is to mark the center line on the firewall as above wherever you want the propshaft to come out and mount the engine on the mount.

Next hold the fuselage between your knees sitting down and look straight at the front of the airplane and rotate/position the engine/mount exactly where you want it.

Use the Great Planes hole locater:

http://www3.towerhobbies.com/cgi-bin...&I=LXK378&P=RF

and insert it through the mount in each of the four firewall holes and turn a few turns. Remove the engine/mount and you have four perfectly located firewall holes to drill and install T nuts.

John

Hi!
Agree! Dave Brown has the best engine mounts!

This is how I do it!
Just bolt the engine to the engine mount with self tapping metal screws or drill and tap the mounts and use either 3mm, 3,5mm or 4mm screws depending on engine size.

Second: Take the mount/engine and hold it against the fire wall and see to that it lines up with the fuselage sides . Most of the time the engine should point straight forward! Then spot glue the mount on with medium or thin Ca glue using accelerator.

Third: Drill holes through the mount into the firewall, put in blind nuts from behind, and screw the mount firmly to the firewall...That easy! I usually don't remove the mount after glueing it on!

Thanks. i used a dave brown mount on the second kouger instead of the two piece that came with the kit, it worked out great. very easy.

Something I tried recently was to position as close as possible on the firewall and drill the holes. Then make a plywood ring to match the back of the engine mount including the mounting holes. Put the blind nuts in the plywood ring. Enlarge the holes in the firewall to allow the bolt some movement. Now bolt the mount through the firewall and into the plywood ring with the blind nuts. You can then loosen the mounting bolts and move the mount within the confines of the enlarged firewall holes.

WK - that works great for flexibility. However that ply ring is not free weight - fine for tail heavy builds, not so fine for nose heavy builds. The buys at SIG send their decent mounts that can be used for any number engines. Engine-specific mounts work better like others have stated. I use Hayes mounts - similar to DB mounts in that they are one piece - different from DB in that the hole mount pattern is "rectangular".

About DB mounts - do multiple sizes (within reason) share the same bolt hole pattern?<br type="_moz"/>

You have to consider the total package. Sometimes it's a good way, sometimes it's not. The ring that I made had any unnecessary meat removed and really wasn't substantial. Just enough to hold the blind nuts. At least it was functional weight and I traded some of the firewall for it

Put the engine in its mount.

Grind/snap the points off a 4-40, 6-32, or 8-32 blind nut (whichever one's shank looks like it'll fit in the mount's firewall holes.

Sharpen the end of 4 of whatever bolts fit your blind nuts to a point.

Run suitable nuts down the sharpened bolts a ways, insert bolts through the mount, spin the mod'd blind nuts on from the back and adjust the whole mess so you've just got some points about 1/16-3/32" long sticking up through the blind nuts. Lay the mount on a hard flat surface and adjust the depth of the points to they all make contact at the same time and there's no rocking from one being high. setting the thing on a small square of 1/16 or 3/32 balsa and screwing the points down until they just make contact with the surface will ensure you won't get a false read on the mount being parallel with the firewall. If you can't slip a sheet of notebook paper (about 3/1,000in) between the points and the hard flat surface, that's gonna be close enough.

Fit your cowl over the whole mess and when you're happy with the way thing are lining up, give a hard shove on the engine, and the points on the bolts will dimple the firewall. Those dimples are where you drill.

If the firewall isn't typical soft ARF ply or is coated with something hard like epoxy and doesn't look like it's going to want to dimple easily, just put some masking tape on the firewall in the general vicinity. The tape will dimple easily and locate the drill hole.