Upgrade ScubaPro C350 to C370 (balanced)?

[stiebs]

Is it a straightforward task? Obviously in theory it's just adding a balance chamber (and removing the spring holder) and changing the poppet, but looking at the schematics of the two, there are a couple of subtle differences that may make it more trouble than its worth? Not having an actual C370 as a reference, hoping someone can chime in

1. The barrel is a different part number. If the diagram I have is accurate, they do appear to be slightly different - the addition of a small slot on the C370 version and a slightly different rotation angle of the key into the housing. So I'm guessing the C350 barrel needs to stay, but will the balanced poppet fit properly in the C350 barrel?
2. The flow deflector is rather different - C350 requires a clip, the C370 doesn't, but I can't see any reason why adding a balance chamber and changing the poppet would cause any issue here
3. Exhaust tee is different, but no impact on the balance chamber
4. Anything else I've missed?

 

[buddhasummer]

Ooh I like this stuff... AL is king of cross compatibility. I'll look into this conversion too for the sake of science. I'll post back....

 

[stiebs]

Ooh I like this stuff... AL is king of cross compatibility. I'll look into this conversion too for the sake of science. I'll post back....

I'm glad at least someone is interested
Although a bit confused about your comment that AL is king of cross compatibility?

 

[buddhasummer]

I was just commenting on the fact that so many parts on Aqualung regs are cross compatible, you can actually make regs yourself that AL do not. So many parts also backwards compatible. I've been studying schematics and playing with their first stages seeing what will work with what... it's a lot.

Scubapro are a bit trickier in that department.

I've never owned a C350 but have owned and serviced a few C370s, my favourite current production second stage actually, I have schematics for both, I'll do some studying.

I do know for example, that's C350 purge cover fits a C370 as I swapped mine out as I preferred the silver S over the blue for a while.

Anyway, like I said I'll take a look and post back.

 

[stiebs]

I've never owned a C350 but have owned and serviced a few C370s, my favourite current production second stage actually, I have schematics for both, I'll do some studying.

This is the first C-series that I've owned. If there's anything that's unclear from the schematics I can take some photos.

 

[buddhasummer]

I love the C370, super underrated IMO, yes, my favourite current production second stage. Silky smooth, effortless.

 

[Kupu]

Is it a straightforward task? Obviously in theory it's just adding a balance chamber (and removing the spring holder) and changing the poppet, but looking at the schematics of the two, there are a couple of subtle differences that may make it more trouble than its worth? Not having an actual C370 as a reference, hoping someone can chime in

1. The barrel is a different part number. If the diagram I have is accurate, they do appear to be slightly different - the addition of a small slot on the C370 version and a slightly different rotation angle of the key into the housing. So I'm guessing the C350 barrel needs to stay, but will the balanced poppet fit properly in the C350 barrel?

With apologies to Simon for jumping in after he bumped the question and offered to help, here are my observations.

The C370 style balanced poppet cannot be installed in a C350 poppet barrel. Or rather, it fits, but then the lever cannot be installed due to barrel design that has the lever openings in slightly different locations.
The unbalanced poppet of the C350 receives the lever in the center & the C370 balanced poppet receives the lever on the bottom side.
Hopefully the photo helps illustrate.

There are also differences in sleeve/flow deflector designs and they cannot be switched between the C350 & C370.
Doing the upgrade looks like more cost and trouble than its worth.

 

[buddhasummer]

Nice, thanks for jumping in Dustin. Was looking at schematics last night and was coming to save conclusion.

I hope you're good

 

[stiebs]

Thanks @Kupu,
Certainly looks like ScubaPro have made a decent effort at differentiating the balanced and unbalanced versions of the C3x0, making sure that no-one cheaps out on the purchase and upgrades

 

[Kupu]

Comparing second stages adds a bit of interest to the local lake dive.
Today it was the C370, C350, & C300 on a single side by side test dive and as expected did not find any real difference when rotating between them while at around 80' depth.
They all got a quick optimization tune of the orifice and micro-adjust prior to the dive but I did not open them up to check condition of the LP seat. I actually liked breathing the unbalanced C300 & C350 more than the C370 by the slightest margin, but that is likely due to different mouthpieces and/or slight differences in tuning, they were all very nice.