DLTX 67 rust prevention

Got my DLTX 67 carb tore apart, bead blasted and now about ready to assemble. I bought the video from Robert's Carburetor on how to rebuild DLTX carbs. In the video Robert talked about treating the carb with phosphoric acid treatments PPG Chemfil DX579 and DX520. From my research this stuff is now call One Choice SX579 and SX520. From what I can tell this stuff is pretty much impossible to get (maybe it's not made anymore??). I really like the idea of getting an etch into the cast iron again because just from sitting around my carb got a little surface rust in some areas. Hate to go through all the work and end up couple years later cleaning it out again because the inside got rusty.

Found this from a number of years back:
https://forums.yesterdaystractors.com/viewtopic.php?t=847795

Seems like even some of the solutions F-I-T listed in that thread are hard to get.

Anybody got any ideas or know any good products being sold today??? Or do you guys not have any issues after bead blasting carbs???

Concrete block etch products are phosphoric
acid. I've done some experiments with
blasted carb parts with mixed results, I
think it boils down to trying to get the
acid neutralized.

Another option is zinc phosphate or black oxide coating.

I've glass-beaded several and they come out nice. Keep them dry till they're on and gassed up, they'll be OK.

Well I went ahead and put the carb together as is from the bead blasting. The ole B runs really nice even with a Wico XB on it.

One thing I did run into while assembling the carb. I borrowed a reamer to get the bushings sized correctly but the shaft would still bind. At first I thought the holes were not aligned correctly because the shaft would fit fine in one or the other bushing but not both at the same time. Took me forever to figure out my new throttle shaft was bent. It was easy to tell when I stuck the shaft in a drill and spun it. So I put rolled the shaft against a straight edge and found which way it was bent. Installed the butterfly in the shaft so when I tapped on it the shaft would straighten evenly. Shaft fit great after that.

Another thing I remember watching in Robert's video was he emphasised on getting the top throttle shaft bushing flush with the inside of the barrel of the carb for consistent air flow. I went a couple steps further and drove both top and bottom bushings in past flush and took a die grinder with a carbide bit and shaved both bushings to the same form as the barrel. This way the butterfly has uniform contact all the way around. Maybe this doesn't make any difference but it seemed like a good idea






This post was edited by 620 John on 03/26/2023 at 08:13 pm.