D420! How about that?

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Thank you very much for your video . As you well know ( because you rebuilt mine ) the pilot to be in tune leaks 6 bubbles a minute

What they say is that a very slow leak is acceptable, not that it's specified. I was able to get my pilot tuned without any leaking. It's a matter of being very careful, actually lucky when it comes down to it, with the alignment of that tiny o-ring on that button. It took me several tries to get it right. That tiny o-ring is originally neoprene if I remember and I used silicone duro 50 or something like that. It's been a few years.
 
The "acceptable leak" standard is a function of the fact that the Pilot has a second knife edge buried inside the poppet stem on a press-fit cone.
It's part of the servo mechanism; it can't be disassembled, and it can't be polished.
You can see the cone through the hole at the arrow, and the servo rod at the left.
Screenshot_20191230-162502_Gallery.jpg


After 50 years, some deterioration of that cone is inevitable, and @halocline has the correct solution: the softest duro o-ring that you can find for that tiny seal. The o-ring is 1mm ID!
Halo is a lucky guy to have a no-leak Pilot, but as long as the main LP seat isn't the source of the leak, it's of no consequence.
 
Service kits are a bit spendy at around $34. The Venturi decal is not apparently available as a separate item which seems strange given it needs to be removed if you want to adjust cracking. I guess SP don't want you to do that.

@rsingler is the decal re usable? Any chance you could post a photo Rob of the top without the decal? Thanks a bunch in advance. Cheers.
 
Service kits are a bit spendy at around $34. The Venturi decal is not apparently available as a separate item which seems strange given it needs to be removed if you want to adjust cracking. I guess SP don't want you to do that. @rsingler is the decal re usable? Any chance you could post a photo Rob of the top without the decal? Thanks a bunch in advance. Cheers.

Considering the service kit replaces so many important parts $34 isn’t bad, I would just leave the sticker off or maybe poke a hole in it.
 
Here's a pic of the D420 without the top decal. The decal is fairly heavy foil, and will come off without bending, if you're judicious. So it could easily be reused. A half-inch hole would expose the hex. A smaller one would allow just the key to fit in, but would serve as a water collection point in the recess for that screw. It's not too ugly without any decal at all.
20191231_071622.jpg
 
What about a mod with a knob permanently fitted in the hex hole, so the diver can adjust the cracking pressure while diving, as in my favourite 109/156 second stages?
 
https://www.shearwater.com/products/perdix-ai/

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