Engine mount shim advise

[SJordan]

Not sure if this belong here or over in the -4 group, please move if needed.

I'm picking up on a -4 project that never got completed. At one point an engine was mounted and the cowl was fitted. I bought the project with no engine or prop and have since built up a IO-360 for the project. I was just about to mount the engine and noticed the Barry mounts that came with the project have a thick additional washer on two of the mounts. I assume these "spacers" were used when the original engine was mounted and the cowl was fitted. So now I'm left wondering how to proceed with hanging my engine. Should I just hang it with no spacers and see how the cowl fits? Any advice would be appreciated.

Thanks
Shawn

[Saber25]

When I built my -4 the engine was mounted without shim washers under the engine tabs. Then the cowl was matched to the engine. I also had the prop spinner and spinner bulkhead mounted to help in finding the center of the cowl opening. I knew that for my style of flying the engine would sag in short order so had the cowl top surface 1/4-3/8 inches lower than the rear of the spinner. By 200 hours the engine sagged enough for the spinner and cowl to align perfectly. Once the lord mounts wore several hundred hours more, the spinner and engine would sag just slightly and that's when I installed the lower shim washers to bring the spinner back up to alignment. That's the way I remember the installation back in 1988. I installed new lord mounts ten years ago and went through the same scenario as to shimming after the new mounts wore in.

Cheers, Hans

[SJordan]

Originally Posted by Saber25

When I built my -4 the engine was mounted without shim washers under the engine tabs. Then the cowl was matched to the engine. I also had the prop spinner and spinner bulkhead mounted to help in finding the center of the cowl opening. I knew that for my style of flying the engine would sag in short order so had the cowl top surface 1/4-3/8 inches lower than the rear of the spinner. By 200 hours the engine sagged enough for the spinner and cowl to align perfectly. Once the lord mounts wore several hundred hours more, the spinner and engine would sag just slightly and that's when I installed the lower shim washers to bring the spinner back up to alignment. That's the way I remember the installation back in 1988. I installed new lord mounts ten years ago and went through the same scenario as to shimming after the new mounts wore in.

Cheers, Hans

Thanks for the quick reply. I'm embarrassed to say this but it appears just a simple read of the book has solved my problem. The washer or "shim" goes on the bottom to clear the mount from the tab sticking off the Lycoming case. I will install my engine with no shims and hope it also sits a bit nose high to cover engine sag over time. I also will be doing extensive aerobatics and am now wondering if I should go with aerobatic engine mounts.

Thanks

[Saber25]

Originally Posted by SJordan

Thanks for the quick reply. I'm embarrassed to say this but it appears just a simple read of the book has solved my problem. The washer or "shim" goes on the bottom to clear the mount from the tab sticking off the Lycoming case. I will install my engine with no shims and hope it also sits a bit nose high to cover engine sag over time. I also will be doing extensive aerobatics and am now wondering if I should go with aerobatic engine mounts.

Thanks

The aerobatic mounts will be the ticket if you plan on yankin' and bankin'.
You'll love the -4, just keep it as light as you can.

Cheers, Hans