Vintage Double Hose

The Cow found you one thru Sheriff diver.

Always amazes me the great group of folks here. Through communications with Bryan, Rob, Eben, Jerry and others turns out my Sea Hunt Forever buddy Ron has a Sportsways valve on a tank that didn't pass hydro. Deal made and hopefully soon I'll have a working set of Sportsways 38s...... Mark

Seat arrived. Thank you to Ron and to Jerry for tracking down the part. Now for the NEW ISSUE!

Turns out the 3/8" burst discs I ordered won't fit. The opening is actually 5/16". Do they make such a size or am I forced to tap out a 3/8" hole. Hate to mess with the manifold anymore than I have to. Suggestions?
P.S. the single SW valve Ron sent me is a 3/8" burst disc size, but not my SW doubles manifold
WTF?

Mark,

I have a set of twin Sportsways 72's at home. I'll look later when I get home. I'll see what I have laying around then. Do you want the burst discs like original with a screw driver head or a bolt style head??

SheriffDiver wrote:Mark,

I have a set of twin Sportsways 72's at home. I'll look later when I get home. I'll see what I have laying around then. Do you want the burst discs like original with a screw driver head or a bolt style head??

Bolt-style head would be great! Mark

My Sportsways twin manifold appears to have the 3/8 disc. All of the spare parts valves I have here that I've checked are 3/8 hole size.

Just looking at your picture Mark and then looking at my twin manifold that hole size looks the same as mine.

SheriffDiver wrote:Just looking at your picture Mark and then looking at my twin manifold that hole size looks the same as mine.

Ok, figure this one out. I took the 3/8 burst disc out if your single SW valve and it fits in one of my double manifold holes but not the other. Neither if my new replacement burst discs fit in either manifold hole but easily fit into your single valve. The threads on the manifold look fine but maybe I should run a 3/8 tap through each to make sure? What thread size tap should I use (if that is the correct term - don't know much about taps.) Anyone? Thanks, Mark

- You can test the thread size real easy by bringing the valve to the hardware store and see which sized bolts thread into it easily. Same for the burst plugs that came out of it... See what sized nuts they thread into. This will tell you tap size, too... BUT, if you did re-tap it, it would require a bottoming tap... not the long pointed ones they sell in the hardware store.
- I have the exact same Sportsways set that you have (It think)... The manifold with straight 1/2" thread and O-ring seal. Mine took the standard 3/8 burst disks. BUT, I was able to get the separate components version... Plug, disk, and washer. I wonder if your one piece modern plug might be a little wide at the copper cap... Maybe that's what is binding and not the threads? ( doesn't look like it from the photo but maybe).

Thanks for the reply Eben. The simplest approach is usually the best approach so I'll be off to the hardware store (again). My research has shown the new-style burst discs are 3/8-24UNF but someone please correct me if I'm wrong (or advise if i am right). I had a bitch of a time getting the old-style recessed plugs out so I could have easily buggered up the threads on the manifold to some degree. I've put too much time, money and sweat into this project to give up now. Maybe a hand tap will reinjuvinate the threads. Mark

ScubaLawyer wrote:Thanks for the reply Eben. The simplest approach is usually the best approach so I'll be off to the hardware store (again). My research has shown the new-style burst discs are 3/8-24UNF but someone please correct me if I'm wrong (or advise if i am right). I had a bitch of a time getting the old-style recessed plugs out so I could have easily buggered up the threads on the manifold to some degree. I've put too much time, money and sweat into this project to give up now. Maybe a hand tap will reinjuvinate the threads. Mark

I tend to think the threads may just be damaged, and maybe not a mis-match on size. I have not seen any plugs with straight threads smaller than the standard 3/8x24, but that's not to say they couldn't exist.

Remember, when you measure the OD of the plug threads they will measure larger than the ID of the threads in the valve. The female thread measurement you get with calipers would be like measuring the bottom of the threads on the plug.

One other thought... Take a good look at the old plug. Did you measure the OD of the original plug? Is it tapered? Maybe it is a tapered 1/8" NPT thread? Seems like I may have seen something like that with a lead plug on a really old valve, but never on a Sportsways.

Hopefully you will only have to dress the female threads gently with a tap.

Mark,

I do have plenty of burst plugs unless you want to use a brand new one. Just throwing that option out there.

SheriffDiver wrote:Mark,

I do have plenty of burst plugs unless you want to use a brand new one. Just throwing that option out there.

Thanks for the offer Ron. I do have two brand new discs I got from a guy who at least claims to be reputable.

Right now I'm seeing if I can gently re-tap the threads of the manifold. Fingers crossed. By the way, the know-everything guy at the hardware store where I was looking for a proper tap just looked at me like I was an idiot and asked why I didn't just call up this "Sportsways" company and buy a new manifold elbow. I asked him if he had a portable time machine and he just looked at me strangely. It was at least funny to me.

Ok you machinist types out there. I started looking for a bottoming tap to clear the threads on my SW elbow for the new burst disk.
I have confirmed it takes a 3/8-24 and have found many taps that size. However, it looks like some taps are UNC (course) and some are UNF (fine) both in the 3/8-24 size. Being the perfectionist I am, I'd like to use the correct tap. Here is my question: Can anyone point me to a source that will tell me if 3000psi 3/8-24 burst disk threads are UNC or UNF? maybe it doesn't make a difference? I've been researching taps until I'm blue in the butt and I figure someone here might know the answer. Thanks. Mark

ScubaLawyer wrote:Ok you machinist types out there. I started looking for a bottoming tap to clear the threads on my SW elbow for the new burst disk.
I have confirmed it takes a 3/8-24 and have found many taps that size. However, it looks like some taps are UNC (course) and some are UNF (fine) both in the 3/8-24 size. Being the perfectionist I am, I'd like to use the correct tap. Here is my question: Can anyone point me to a source that will tell me if 3000psi 3/8-24 burst disk threads are UNC or UNF? maybe it doesn't make a difference? I've been researching taps until I'm blue in the butt and I figure someone here might know the answer. Thanks. Mark

Mark, there is a big difference. The "3/8" is obviously the OD measurement, and just as important is the "-24", which indicates the number of threads per inch (tpi), also referred to as "pitch". All the 3/8 plugs in my limited experience are -24's... which is the fine thread, "UNF". The "UNC" stands for Unified Coarse, which is 16 tpi in the 3/8" diameter thread system. Any decent hardware store should carry both types.

So, all you need are two 3/8-24 (same as 3/8 - UNF) taps. if you can't fine a bottoming tap. Gently use one tap to renew the existing threads in the valve body, but be careful not to let the tip damage the flat sealing surface down in the valve. Not all the thread in the hole will be dressed yet.

Next step is to create an "almost-bottoming-tap". Carefully grind the tip off on one tap to remove about half the incomplete diameter "starter threads". Keep the tap from overheating on the grindstone by only doing a little at a time and dipping in in oil to cool often. Be patient and just do a little at a time to keep from totally destroying the temper (think "hardness") of the tap. You should end up with a near-perfect flat tip on the end of the tap. It will now go further into the valve with the full threads, reshaping the deeper threads. Again, don't let it damage the flat sealing surface in the valve - Maybe a good idea to leave a sacrificial copper or plastic washer down in there during this process!

Then you can grind more off the tap, in effect creating a "bottoming tap", and repeat the assault on the valve until all the threads are cleaned up, dressed, renewed, etc. Then try the new plug after thoroughly removing all the brass debris.

BTW, if you don't want to go to all that making a tap trouble I will be glad to loan you one!

Hope this helps!
BT