Wed Jul 28, 2021 11:59 am
I've been rebuilding a bunch of Dacor regs lately. I ran into a source of parts and have been able to complete a few that were languishing in the bin. I got a few more complete regs as well. They are R-2s, R-3s, and R-4s. I was able to get some NOS main diaphragms, some good used diaphragms, NOS HP diaphragms, NOS exhaust mushrooms, NOS non-return valves, and some mouthpieces with wws, in both sizes.
It has been interesting to see this new stuff, and to take the regs apart. One thing that is striking is the different styles of main diaphragms. They are not all the same. There are early domed, later domed, and accordion pleated (of possibly two types). There are upside down domed exhaust diaphragms. There are several kinds of plates on them, as well.
Some are very flexible, and some have stiffened up with age. The stiff ones are recently removed from a regulator. The stored ones are nice and floppy. The Dacor diaphragms were not stiff when new, unlike the hoses which were rather.
The reason Dacor 2500s don't perform as well as a DAAM or some other 2 stage regulators is due to the simple second stage. Making matters worse, the R-1s and R-2s were made with the second stage positioned 90 degrees away from the intake horn.
The R-3 is a bit better. They positioned the second stage in front of the intake horn, making a more direct path into the intake. The second stage orifice is simply a drilled through bolt with a cone on top. A lever with a seat on the end seals it. The air jet from the second stage is blown into the face of the LP seat, and disperses into the box.
Coupled with the 1" mouthpiece and tiny, buried non-return valves, this all makes a fairly hard breather. Why they thought they needed to throttle the things even more with the dial a breath vane....
The R-4 can breathe as well as a DAAM due to its redesigned second stage. Part of the problem with R-4s is the second diaphragm. If you replace it with a duckbill, the exhalation effort is improved. The other problem is the too small mouthpiece with its small non-return valves. It is way better than the 1" set, but things are easier with a USD hoseloop. They called the larger mps 1 1/2", but they are significantly smaller than USD 1 1/2" mps.
I've had some C-2s, C-3s, and C-3Ns that are fine breathers, and they are basically no different than the R-4. In fact, the C-3N is a beefed up R-4 with a duckbill instead of a second diaphragm.