Dacor 4/800 Balanced Conversion to DH

[Vancetp]

As I mentioned in my Titan II conversion thread, I'm working on a Dacor conversion as well. Herman has already done this, and his blogs on his Dacor Derringer make interesting reading. I decided to follow in his footsteps and try to make one that is somewhat simpler, using available parts.

I have saved you lot from the details of my agonizings over the Dacor 4/800 Balanced conversion that are posted elsewhere. This conversion is tricky, as you might know by reading Herman's adventures. Drilling a hole for the second stage w/o breaking out through the first stage body is a big problem. It can't be very wide and it can't be very deep.

I began with the idea of a modified single hose second stage with an integral hard seat, but abandoned it due to space limitations.

IMG_4576 by Vancetp, on Flickr

The adjustable seat in the modded second stage is just too long, and won't fit down into the drilling in the first stage. The second stage lever will be much too high. This doesn't mean a second stage with an integral seat couldn't be made, but I dropped the idea for a much simpler one.

I made a hard seat that is pushed down into the drilling and sealed with an o-ring. It isn't threaded at this point, but it might need to be if it leaks. The hole is threaded most of the way down, leaving a smooth spot at the very bottom for the o-ring.

IMG_4606 by Vancetp, on Flickr

A pipe nipple screws in which presses the seat in place, and the second stage seat/lever carrier screws on to that.

IMG_4615 by Vancetp, on Flickr

The cap will be held in place by a groove and set screw, like this Titan II.

IMG_4342 by Vancetp, on Flickr

Lever height is perfect! Getting close to making bubbles!

IMG_4625 by Vancetp, on Flickr

This leaves me with a second stage pretty far from the intake air horn, and potentially the need for a venturi tube or air director baffle. That will be another fun episode.

[Vancetp]

More progress. I drilled into another first stage to cut a new second stage opening at 10 o'clock vs 12 o'clock in order to position the air jet closer to the intake air horn. This position is almost identical to the Titan II conversion and where a Trieste will fit in the can. If the jet is drilled so it points down the air horn, it works well.

IMG_4650 by Vancetp, on Flickr

IMG_4651 by Vancetp, on Flickr

[Herman]

I like where you are going with this. If there is enough space around the body to move the port, that should work well.

[Vancetp]

My second stage only requires drilling a 1/2" hole, so there's more room to work with. I can get even closer to the horn than I did, maybe, but was too chicken to push it. I might. I've got another body to experiment with.

[Herman]

I have 2 or 3 bodies if you need another one.

[antique diver]

Good to see some serious experimentation going on, and there seems to be a lot of those old regs still around.

[swimjim]

I have a few Dacor Olympic 400's in my collection. They are really nice single hosers! They breath great and are built like a Sherman tank! I know it won't happen, but I'd love to own a double hoser conversion. I have almost all the double hose variants in my collection and I dive them occasionally. Especially the Clippers and the R 4's.

[Vancetp]

I have 2 or 3 bodies if you need another one.

Thanks for the offer! If I ruin one I might take you up on it. My drill press/XY table setup isn't very accurate, and I might not be able to get the hole to go where I want it exactly, so drilling very close to the edges will be tricky. I may need to put some better bearings in it to reduce the slop. Or I might just consider this box checked and go with what I've got.

This hobby gets expensive what with all the tools, bits, cutters, vises, and upgrades to the machines and all.

[Herman]

Tell me about it.

[Vancetp]

Did some more tweaking. I've been fooling around with second stage springs. I regret making the threads 18 tpi, since it seems that the adjustment isn't as fine as I'd like. I filed the grooves for the second stage cap setscrew retainer, and drilled the body for it. It is good. I need to assemble the regulator and test the jet for venturi action, but the thing pushed a lot of air out the intake horn w/ no diaphragm or bottom can on it. I think it will work great! I'm very hopeful for this conversion....

[Herman]

No need to assemble it, just drop on a diaphgram, make sure its in the groove and push down on it, If the venturi is working, it will pull it down hard and free flow hard. Just DON"T try to breath on it with your mouth, lung expansion is a bad thing.

[Vancetp]

No need to assemble it, just drop on a diaphgram, make sure its in the groove and push down on it, If the venturi is working, it will pull it down hard and free flow hard. Just DON"T try to breath on it with your mouth, lung expansion is a bad thing.

Right! Never breathe off the intake horn. If you don't get hurt, it will at least scare the bejaysus outta you. I'll do the test with the diaphragm only as you suggest. The FX cans with an OEM diaphragm do seal it up well. Not so much with a reproduction silicone diaphragm.

Thanks for the suggestion, Herman.

[Vancetp]

Here's a shot of the second stage parts:

IMG_4769 by Vancetp, on Flickr

And here's the finished regulator (I stole the boxes off one of my Titan IIs):

IMG_4739 by Vancetp, on Flickr

IMG_4741 by Vancetp, on Flickr

It's going for the pool test this week!

[Vancetp]

I did one more. The hole is closer to 9:30. Due to slop in my drillpress, and not being able to control the cut with the accuracy I want, it got closer to the big hole for the HP diaphragm than I would have liked. I thought I'd munched this body, but it turned out ok, and I didn't cut into the big adjuster body threads. So this one is even closer to the intake horn, and gives a better shot down the pipe.

I'm making some redesigned second stages and some new levers tomorrow for the Dacors and the Titans, so I'll post when I have pics.

[antique diver]

Good to see you building new stuff!
The shape of the Dacor first stage ought to put the regulator case right against your back where it will do the most good.