The New-Zealand-manufactured Fynspray galley pump is the best way to turn a Scepter water can into a convenient and fast dispensing system. The normal procedure, shown on several sites, involves cutting off the base of the larger of the two small sub-caps on the main Scepter screw-on lid, then drilling a one and one-half-inch hole around the remnant hole, which is only about three-quarters of an inch in diameter. You can do this on the lid that came with the can, or on a spare, which is what I did.
If you have a drill press and can secure the cap, this is an easy task. However, if you try to do it with a hand drill and a one and one-half inch hole saw, you won’t have any guide for the hole saw and can wind up really buggering the job. I found an easy work-around.
Instead of cutting off the screw base for the small cap, I left it in place, including its cap. I then used a cheap hole saw with a protruding guide bit, and drilled straight down through the top of the cap. The hole saw is slightly smaller in diameter than the cap, so it will shave off the circumference as you go. However, it will perfectly center the drill bit. If your hole saw is deep enough you can go all the way through. Mine wasn’t quite deep enough, but it scored the cap deeply enough that, by unscrewing and discarding the small cap, it cut the rest of the way through with zero walking. Cut off the unneeded securing ring, and . . . done.
The Fynspray pump works on both the up and down stroke, so it’s very fast. And you can leave the can upright, even secured in a holder if desired. The smaller cap on the lid serves as a vent for full flow.
The Fynspray mod is infinitely better than the insultingly ineffective Scepter hose and nozzle, which requires you to lay the can on its side, and has no provision for venting, so you must constantly tip the can up to relieve the resulting vacuum. Tip: If you’ve already bought the Scepter nozzle, you can repurpose its hose to make the extension for the Fynspray pump.
Fynspray pumps are available at Fawcett Boat Supply, among other places.