I'm using the Great Planes universal engine mount with a Saito FA100. I drilled and tapped the mount for 8-32 bolts.

Thing is, the bolts are off by just enough to keep them from fitting right. I used a hot nail to mark the holes with the engine sitting on the mount, then drilled them, but they're still off. I'm really cranky at the moment because I was so patient lining things up, checking to make sure the holes were in the center of the mounting lugs, and they're still off.

I was wondering how others mount their engines in this size. Does anyone drill thru and use a nut on the bolt? Or only in addition to threads in the mount? Just curious. Looks like I'm going to have to buy another mount anyway.

-Joe

Tele,

You see all kinds of things done at the flying field. Try to resist making the holes larger in the 100 though.

Your experience is a problem that many of us have faced in the past.

If the mount has a flat area underneath to hold the nuts, you could drill the holes out to clear the #8 threads and put nuts on there.

It's your mount.

enjoy,

Jim

I use a hot pushrod end to score the mount then drill it for the bolts. If it doesn't line up after that, I loosen the bolts at the firewall, tighten down the engine bolts and then retighten, and locktight, the firewall bolts.

Re-drill the holes in the mount slightly oversize so the bolts will fit, then use nuts on the bottom of the mount. (sand or file a flat if it really needs it)

This is quite a common thing to happen,
especially when trying to make a mark on the mount which
is flat black and hard to see.
You can try dropping some talcum powder thru the engine holes next time or stick a piece of masking tape over the mount then
laying the engine on it.

Will the bolts fit if it is just drilled the next size up ?
Could you leave the bottom part of the hole at the original size ?
This way the bottom part will act like a nylon lock nut.

I managed to get 3 of the bolts to thread in. Looks like I'll just have to drill the one through.

Thanks for all the advice

-Joe

Hi!
The solution is real simple...
Just put the engine on the motormount! Use medium Ca glue if its hard to hold it thight! Yes Ca glue in small amounts on the side of the engine lugs.... and kicker!
Then use a long drillbit and drill one hole through the motormount having the engine lug hole as jig. Then put the engine a side!
Take the enginemount and make treads in the hole you just drilled.
Screew the engine to the engine mount with the single bolt. Now the engine is mounted on the mount and the rest of the holes could be drilled using the long drillbit. But most of the time the drillbit is not long enough.... so just drill some small marks in the plastic mount and then unscreew the engine again and now you have room to drill the last 3 holes whitout hitting the head or side of the engine with the drill chuck. After this just tread all 3 holes and you are finnished.

Regards!
Jan K
Sweden