Hi guys I have used a product called STAG here in OZ many times over the years to seal many different liguids/gases/greases and it works a treat. I think it is a USA product and is suitable for many applications, I was first put onto this product as a young motor mechanic when I was having trouble sealing a tripple fuel block ( one fuel line into a fuel block with a three fuel lines out ) for a set of tripple carbies I was playing around with at the time anyway I had tried all types off sealant ( could not afford a quality fuel block as carbies had cleaned the wallet out and had to make do with cheapo fuel block ) anyway that was about 24 years ago and I still use Stag to this day. Have only ever had 2 tubes of stag the current tube is about 10 years old. This stuff is recommended for all types off sealing jobs Hi preasure steam/petrolium based liquids. It has never failed me and I have used it to seal anything you can name. ( must check to see if it is still avaliable here in oz) Anyone else out there used this product I would love to here from you. not many people hear in oz have ever heard of it. As you can tell I am a huge fan of this product. As for the pet cock/fuel econmy thing you can have all the fuel flow you want,its the jets / needles/ air flow plus the right wrist that control how much fuel you burn
Cheers Muzza