Upgrading military valves

[avonraft]

I've got a Hyside with the metal military screw valves. I'd like to change them out for Leafield C7s. Has anyone here ever done this? I know I'll have to cut out the valve boot, which will leave a sizable hole. Do I need to do an inside patch when installing the new valve in the tube, or will just gluing on an outside patch work OK?

Any hints from you repair experts would be appreciated.

[slickhorn]

I got into this a bit with an Avon that had military valves. I tried a couple of things, and generally had success.

First, I got the actual valve out of the boot. Then, using a head gun and pliers, I got the boot separated from the tube material, which leaves you with a ~3" hole.

I tried different valves in the replacement step. The first one was the Avon style recessed leafield which also amounted to a boot. I applied glue to the inside of the tube and the outside of the boot, 2 coats, let it dry to touch. Then I rolled the boot like a taco, got it inside the tube, and used the heat gun to reactivate the glue. Worked ok, but a fair bit of work.

I also tried using a Halkey-Roberts valve, and for these, I first cut a layer of fabric to match the size of the hole left by the old valve boot. I then cut a piece that overlapped the valve boot hole by ~2" on all sides, and glued the smaller disc to the center of that. I trimmed the hole for the valve, seated the valve in the 2 ply disc, then glued the overlapping section to the tube.

I don't know why you couldn't use just the larger disc, and be ok. but this worked fine for me. It's a lot of prep work to get things ready to go so the replacement is bomber, and I only used 2 part stabond for hypalon.

good luck -- love to see some pix when you finish it up.