FAB air box install anticipating engine sag

I just spent three days installing the tunnel from the front of the lower cowling back to within 1/4" of the air box per Vans instructions. I put two washers under the front two mount plate to carb bolts to lower the air box during cowl tunnel install per Vans instructions to allow for future engine sag. After finishing, I am wondering if this was a good idea. Looks like I have about 1/4" vertical difference between the tunnel and the air box inlet. Now I am wondering how the black baffle fabric will seal this. I can rivet the bottom "U" shaped piece to the air box and I suppose it will seal okay, but the separate top piece would be just hanging up their with no forceful seal, 1/4" above the top of the tunnel. Now I am wondering if I should have ignored Vans suggestion to build for future engine sag. Comments, suggestions, pictures appreciated.

Here is a close-up photo of the carb air inlet showing the "sag" gap:
http://www.aclog.com/rv-9a/images/Firewall%20Forward/c6065bd0f201a3a1bf802f3d566aa5338879_IMG_0248.jpg

Mike

I am at this stage on my very slow build RV6 and wondered what you finally did (if anything) to compensate for engine sag.

One suggestion is to fit a 0.125" oval "packer" ring between the Mount Plate & Top plate (thus forcing the inlet down). Complete the alignment with this packer in place, and remove the packer(s) once sag occurs.

Instead of a 0.125" packer two 0.063" may be easier & enables more adjustment.

Regards
Graham
New Zealand.

Graham said:

Mike

I am at this stage on my very slow build RV6 and wondered what you finally did (if anything) to compensate for engine sag.

One suggestion is to fit a 0.125" oval "packer" ring between the Mount Plate & Top plate (thus forcing the inlet down). Complete the alignment with this packer in place, and remove the packer(s) once sag occurs.

Instead of a 0.125" packer two 0.063" may be easier & enables more adjustment.

Regards
Graham
New Zealand.

Click to expand...

FWIW, I did not use the spacer washers, and after > 100 hours, have seen no perceptible engine sag. I used the engine mounts that came with the FWF kit (Lord mounts).

Chris

Add shims to the upper engine bolts to make it straight (and the spinner in the correct position) and then simply remove the shims in the future if it does sag?