Vintage Double Hose

Well, it took a year’s worth of ‘spiramentin and the knowledge of those far more technically savvy then me, but I finally got my Trieste to breathe well.

Most folks will tell you, me included, that a stock Trieste most often breathes like you are sitting at the bottom of the pool sucking air through a garden hose. It took a longer-than-normal custom made lever from Phil, and a 2nd Stage body drilled and equipped with adjustable venturi set screws courtesy of Bill T. of Texas, to make my Trieste extremely easy breathing.

I’ve gotten my stock Trieste down to 1.5" H2O cracking pressure (at 150 psi IP) but the venturi effect is non-existent and sustained cracking is 3+ inches of H2O. With Phil’s longer lever I got cracking pressure down to .7" H2O but the sustained cracking pressure didn’t change. Enter Bill T. with the concept of drilling two holes in the 2nd Stage body and putting tiny set screws that will move up and down to adjust the venturi.

Today I installed Phil’s lever and Bill’s modified 2nd and cracking pressure is still .7" but the venturi now kicks in (after about 4 or 5 one-half turns of the set screw outward from the closed position) immediately with a sustained effortless flow. I checked the venturi on each ½ turn of the set screw outward. At first the venturi was too powerful and it sucked the diaphragm down and held it there in freeflow mode. I finally found the sweet-spot and the reg now breathes fantastic. Very powerful venturi actually. Put a dab of locktite in each hole. Can’t wait to try it out in the ocean!

Nice! COVID back burnered my Trieste project. One of those levers.... hmm..

Mark, that is a very interesting concept, and I am anxious to hear a dive report.

Greg

Neat project! I've been hearing of the different techniques to make the Trieste work well... And now my mind is on the lookout for an available Trieste to buy and fix up myself. I've heard various different approaches to the diaphragm. What did you do with the diaphragm on this one?

SurfLung wrote: ↑

Thu Sep 03, 2020 9:40 am

What did you do with the diaphragm on this one?

I bought a new silcone diaphragm from this guy named Rob at The Scuba Museum.

Completed my Modified Trieste rebuild. Sounds like a sports car engine when the venturi kicks in.

That lever is a PITA to make. I've been fooling around with levers lately, and have gone from this:

IMG_4769 by Vancetp, on Flickr

To this:

IMG_5400 by Vancetp, on Flickr

To this:

Triestereprosm1 by Vancetp, on Flickr

The Trieste type bend at the diaphragm end isn't easy, but the double bend at the body end is no joke to make. I think it is a good thing, because it raises the whole lever upward and lessens the needed lever bend up to meet the diaphragm. It also helps to keep the other second stage parts from interfering with the diaphragm. I'm working on an easier method of making them. Lots to do.....

Phillip, you are getting really good at levers, nice job.

Thanks, Herman! Don't mean to hijack this thread, but I thought people might be interested. I'm thinking about incorporating the set screw idea in my second stages, as well.

Contributing is NOT hijacking! Thanks Mark, Bill, Vance, SwimJim, and everyone else for sharing so much good information on the Trieste. You got the old FEVER going in me again and I've been shopping around until I finally bought Allan's Trieste II that he posted for sale on this forum. This one was tuned up and upgraded (hoses etc.) by Greg Barlow awhile back. Allan never dove it though. So, I'm excited to check it out. I never was interested in the Trieste because I had heard it was a hard breather... And I like regulators I can DIVE with.

THIS THREAD... Is very encouraging and I'm looking forward to getting my new Trieste tuned up to good diving condition!