I couldn't bear the thought of spending $57 for a 3/4" firewall penetration kit so I did some digging around on the internet. I found these on Amazon in a variety of sizes and quantities. Two for $7.85, and free shipping with my Prime membership: https://www.amazon.com/uxcell-Diame...ne+Stainless+Steel+Pipe+Tube+Weld+Neck+Flange . 2" X 1/2" stainless steel washers from my favorite hardware store at .45 cents each. They work as a backer on the cabin side of the firewall. Just drill out the 1/2" hole to 3/4" with a good Unibit and deburr, then match drill the mounting holes, or drill new ones to suit. I had a foot of 1" I.D. silicone fire-sleeve leftover from another project and have a tube of 3M 200 Fire Stop sealant to seal up the firewall on hand. Add a couple SS worm clamps and your good to go. The flanges have a drilled hole in side of the tube for a set screw but the sealant, worm clamp, and overlaying fire sleeve will take care of that. I have a TIG so will probably weld the holes closed though I do not thing it is necessary. So here I have 2 nice stainless steel firewall penetration kits for about $5.00 each.
[/url]DSC01987 by David C, on Flickr[/IMG]
[/url]DSC01988 by David C, on Flickr[/IMG]
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