Correcting Engine Sag

[Auburntsts]

Has anyone corrected RV-10 engine sag with a shim under the lower mounts? If so, what did you use for the shim? And yes I know folks installed their cowls in anticipation of this but I didn't so I'm looking for known shim/washer solutions.

 

[Ironflight]

I haven't done it on a -10, but have on numerous other airplane's. Assuming you have a little extra length in your lower engine mount bolts, you can take a large washer (the size used on the LORD mounts) and cut slots in it (or them) so that all you have to do is hoist the engine, loosen the bolt, and slide in a washer/shim. Tighten things back down, and you'll have tilted the motor up. Some might argue that the shim could work loose and fall out, but I have never seen any come loose once the bolts are properly torqued.

Anecdotal evidence, I know.....

 

[az_gila]

I haven't done it on a -10, but have on numerous other airplane's. Assuming you have a little extra length in your lower engine mount bolts, you can take a large washer (the size used on the LORD mounts) and cut slots in it (or them) so that all you have to do is hoist the engine, loosen the bolt, and slide in a washer/shim. Tighten things back down, and you'll have tilted the motor up. Some might argue that the shim could work loose and fall out, but I have never seen any come loose once the bolts are properly torqued.

Anecdotal evidence, I know.....

I've done it too on a certified plane.

No need for a slotted washer though, I found once the two lower bolts are loosened it was easy enough to pull the bolts out and add a whole washer/spacer/shim one at a time.

Note that the shims have about a 2:1 effect. A 1/8 shim will move the spinner about 1/4 inch.

It was much easier than the initial engine installation on a RV.

 

[Bavafa]

How about shimming the engine mount to the firewall instead of shimming the engine mount to the engine. At a glance, it seems there is far less work as there is no need to remove any thing to get to the engine bolts. Andy down side to this method?

 

[Auburntsts]

How about shimming the engine mount to the firewall instead of shimming the engine mount to the engine. At a glance, it seems there is far less work as there is no need to remove any thing to get to the engine bolts. Andy down side to this method?

That's a no-go in my book. The most obvious problem is the RV-10 engine mount attaches to the firewall at 4 points on the bottom and 2 on the top and would be a two person job --plus access to cabin side of the inboard 2 bolts ain't easy, not that the outboard ones are a piece of cake. Easier just to mess with the 2 bottom engine attach points. Plus the nose gear, which is integral to the mount, hinges at the 2 inboard attach points so I don't know what shimming would do, if anything to the nose gear (maybe nothing but I'd prefer not to find out.)

 

[dlloyd3]

To read about the washer/shim/spacer to raise the engine on a Mooney, google Don Maxwell Aviation. Publication tab, aligning an engine. Seemed like a standard washer raises the spinner 1/2", a light washer 1/4".

 

[Bill.Peyton]

I used one shim washer under each of the lower engine mounts. It's a standard engine mount shim that I obtained locally at our FBO shop. One washer did it, and I agree, it's at least a ratio of 2 on thickness of the washer verses engine height shift at spinner. Do not drive the bolt all the way out, just enough to slide the shim in, it makes it much easier. I also made a pin out of a spare bolt to help with the reinstall. Before you install the washer, make sure you have enough thread length to accommodate the shim.