Cothran valve tuning

[Hobbyman2007]

I've got a valve and tube coming for a .25 cal build and looking for some info from others with the valve.Ill be using a bottle regulated to 1800psi or so,I can adjust if necessary . I'd like to know what hammer weight works best and what kind of shot count your set up is getting . Any other info is appreciated. There are already quite a few posts about the valve but none are giving any real detail about tuning .

[npunk42]

.25 Mrod? Max FPE or shot count? Pellets?

[kj]

i dont have one. i know they are made so that they dont need a hard hammer strike to open. did you contact don ? easiest to call him.

peace
kj

[Hobbyman2007]

I have talked to Don about the valve and the power it makes .What I'm looking for is tuning info and a baseline as to where to start.
I'm not looking to make huge power with the valve , not right now anyhow.

[rsterne]

Surely Don can give you that information?.... I get the impression there are few people using them, and they like to keep the info close to their chest.... No idea why, but some just don't want to share, I guess....

Bob

[Hobbyman2007]

Thanks Bob , I got the valve in today and did the test fitting . She's all aired up and testing for leaks. I didn't want to bug Don too much with the finer details ,he's a busy guy. I'll gather as much info as I can and let the cat out of the bag once I'm done tuning. Hopefully tomorrow.

[Gippeto]

Measure the sealing diameter and the piston diameter. Work out the force holding the valve closed at intended pressure.

Compare that with something "known"...2240, QB, Disco as far as force required...and striker mass.

Will give you a rough idea as to a starting point.


Al