Diana 35 power dreams

[evert]

The Diana 35 is a really nice gun, and examples in mechanically sound condition turn up once in a while for an OK price..
So I'm dreaming for more power, and am looking for inspiration.. Has anyone done som mild re-engineering on the gun?
How does it react to transfer port sleeves, and is it possible to increase its stroke?

[Shed tuner]

give us the vital stats and we can look at the numbers.

stroke, piston weight, TP dia/length, calibre

[evert]

give us the vital stats and we can look at the numbers.

stroke, piston weight, TP dia/length, calibre

That means I'll have to take one of them apart again

[TonyL]

It will be nice to hear how any '35 projects go.

At the dawn of my airgun enlightenment, which came in 1977 with the launch of Airgun World (I'm sure it will be the same for many), the '35 was amongst the European "exotica" we were introduced to. By all accounts a lovely gun of "medium power" and hence didn't receive the attention that the more illustrious "power houses", the HW35, FWB Sport and BSF B55 received due to the quest for power back then. The company's own 45, and later 52, addressed these issues, aw we know.

So, yes, it'll be very interesting to hear of the vital statistics and how it can be sensibly fettled to improve things further. I'm guessing that a good few people on here will have first hand knowledge.

[Hsing-ee]

I think the model had a short, square stroke and the tuners never really bothered with them.. a good one will do 10.5 in .22 calibre, most will do 9 ish. Back in the day it was never chosen for FT or anything, the .177 model giving rather feeble power. My shaky memory points to a TP issue as well.

As Jon suggests the experts will need the vital stats to give their verdict.

An adaptor and a parachute seal might be one place to start (Vortek sell these), but I think the swept volume is an issue and also the three bearing trigger is not fun to strip and replace repeatedly while you get everything right.

The Diana old 35B was claimed to be powerful ie nearer to 12 fpe but its an old model and I think it was probably marketing hype.

Like many requests to force more power out of an old classic, which is what a 35 is, probably the best thing to do is check the leather seal and the breech seal, relubricate it and enjoy its gentle manners and fine handling. It will do excellent service out to 30 yards and is very accurate, just at longer ranges the trajectory drop might be annoying. If you long-stroke it then it'll just lose its charm...

[Geezer]

As above:

https://www.pyramydair.com/blog/2008...the-contender/

[evert]

Like many requests to force more power out of an old classic, which is what a 35 is, probably the best thing to do is check the leather seal and the breech seal, relubricate it and enjoy its gentle manners and fine handling. It will do excellent service out to 30 yards and is very accurate, just at longer ranges the trajectory drop might be annoying. If you long-stroke it then it'll just lose its charm...

But I have three, and one of them is a rusty old wreck... So I can keep two nicer guns close to original, and then do all the stupidity to the rusty one.

[TonyL]

I was all for agreeing with Al there, evert, but now you put it like that......

Go easy on the old girl, though.

[Hsing-ee]

But I have three, and one of them is a rusty old wreck... So I can keep two nicer guns close to original, and then do all the stupidity to the rusty one.

TBH I would go the other way with it, go for low recoil and more accuracy. Fit a parachute seal and a weak German-spec spring, a diopter and weight the stock to get the thing up to 4.5 kg, fit adjustable match butt-plate, make up a raised cheekpiece and deep fore-end (or cast a tailor-made Tylorean cheek-piece from resin), sleeve the barrel for more weight up front, make up a flat trigger blade. Then use it as a 6 yard or 10 meter gun in your garage, basement or hallway. Chopping down matches at 6 yards is great fun.

If you do it well enough then engrave '35 Match' on the cylinder to confuse future generations of collectors.

The best way to get more power out of the Diana 35 would be to replace the action with one from an HW80. You'll need the barrel as well and the trigger unit. 26 joules easy.

[p.j.]

I bought one a couple of months ago, 1976, .177 complete with opens, and generally in very nice condition. I paid £80 which I think was a good deal.
I have another in .22, which isn't so good. Only a matter of time before they come apart!

[jlb73]

So,vital stats as required are:
-stroke 68mm
-t.p. 26×4mm

I have tried to improve mine in 177cal :
-Home made delrin rear guide and top hat
-Vortek seal and piston rear butonned
-t.p. reduced first at 3mm and last at 3.2mm
-stroke 76mm (+5mm due to the thinner Vortek seal and +3mm by cutting the front of the piston with a lathe.

Lot of work...but almost no power raise!
Only 11 joules with jsb exact, a little less with express or heavy, so the diameter of the t.p. is fairly good.
The most improvement is the quieter behaviour,much softer(the reduced t.p. helps)

[IMG]20210311_205259.jpg [/IMG]

[randl]

I seem to remember and I might be wrong! But wasn’t there a 35s version back in the 80s that made a bit more power as standard?

[p.j.]

Might have been more power. It had a deeper angular stock,

[randl]

Yes , and chequering on the forend I think. Was probably very early eighties before the 45 came out ?

[Shed tuner]

So,vital stats as required are:
-stroke 68mm
-t.p. 26×4mm

I have tried to improve mine in 177cal :
-Home made delrin rear guide and top hat
-Vortek seal and piston rear butonned
-t.p. reduced first at 3mm and last at 3.2mm
-stroke 76mm (+5mm due to the thinner Vortek seal and +3mm by cutting the front of the piston with a lathe.

Lot of work...but almost no power raise!
Only 11 joules with jsb exact, a little less with express or heavy, so the diameter of the t.p. is fairly good.
The most improvement is the quieter behaviour,much softer(the reduced t.p. helps)

to be honest, that sounds a good result ! Taking the port down was defo the right way to go - although I might have left it at 3.0
My guess is the power is fairly neutral, as you have sacrificed some combustion when moving away from leather.

70mm stroke @28mm bore, with a long TP, is always going to struggle for 12fp in .177 Compare with an hw35 say, similar stroke and port length, but an extra 2mm dia clylinder, which is a fair bit of extra air.

PS what was the piston weight ?

ATB