The following article is taken from the AMA National Newsletter.
Please see bottom of page for contact information.
This article is by Fred Harvey.

SHOCK-MOUNTING SCREWS

Engine cowlings are often a problem. The plastic cowlings that are supplied with most kits are made from thin material that is prone to cracking due to the severe vibrations that come from a high speed, single-cylinder glow engine. Fiberglassing the inside of these cowlings makes them more durable but not perfect.

Traditionally, cowlings are mounted by gluing small wooden blocks to the firewall, then small wood screws are run through holes in the cowling and into the wood blocks. This rigid mounting means that all those engine vibrations get transferred directly to the plastic. Vibration either causes the mounting screws to come loose, or causes stress cracks in the cowling around the screw holes, or both.

You can fix his problem by shock-mounting the cowl. Drill a hole into the mounting blocks just large enough to shove a scrap piece of fuel tubing into it. Leave about 1/32" of the tubing protruding above the top of the hole to come in contact with the inside of the cowl. Small wood screws can be used to fasten the cowl. Not only does the fuel tubing help to isolate the cowling from vibrations but it will also keep the screws from vibrating loose!

from Vapor Tales
Fred Harvey, editor
307 N Brook Forest Rd
Derby KS 67037