Imagine my dismay after completing my year long restoration, only to find gas pissing (like a leaky old man) from the overflows. I pulled the bowls - leak tested with water - no leaks??? Checked the correct float operation & adjustment - 100% OK.
Added some very tight 1/8" ID tubing to the bowl stand pipes - that kinda worked for about a week on 3 of the carbs.
Went back to the water test - this time I added air to the equation by blowing compressed air up through the drain pipe from the bottom. This method revealed cracks in ALL four bowl stand pipes - you could clearly see exactly where the crack was from the air bubbles.
Soldered up the cracks - now 100% LEAK FREE!!! I can leave the petcock on for days without any worries - not a single drip!
Lessons Learned:
1. Filling the bowls with water and waiting for a drip will not work - I had 3 cracks that wouldn't leak when I filled the bowls on the bench - If I had not applied air, I would have never found the cracks.
2. Tubing over the pipe is only a temporary fix at best - even the tightest fitting tubing will expand after soaking in gas for several hours/days.
3. Soldering cracks is VERY easy - even with a regular el cheapo solder iron. Just make sure brass is clean and free of fuel/contaminants.
4. You can have LEAK FREE overflow tubes if you double check those Float Bowl Stand Pipes. I would've never imagined that ALL four of mine had cracks - plus some of the cracks were very hard to detect - with the naked eye they looked fine.
