Adjustments in Tuning a PCP

[SpiralGroove]

Hey more advanced tuner's than ME ,

In terms of Valve Stem Strike & corresponding dwell time , what is the difference between:
1) Heavy vs. Light hammer
2) Heavy vs. Light Spring or different RVA adjustments
3) Shorter vs. Longer Hammer Travel

What is the best method to find the sweet spot on any given PCP, given 1), 2) & 3)?

Thanks ........... Kirk
 

[rsterne]

Hammer weight changes the momentum and hence the dwell but not the energy and hence the lift, nor the ability to crack the valve against a given pressure....
Spring force change (rate or preload) changes the energy AND momentum, and hence dwell, lift and cracking....
Hammer travel also changes energy and momentum, and hence dwell, lift and cracking....

Your 4th question has no one correct answer, as it is a combination of lift and dwell, and the ability to crack the valve against pressure, that affect the tune of a PCP.... All are interrelated.... In general terms, a low powered gun, or one operating on low pressures, can benefit from a light hammer.... On the other hand, if you are building a 500 FPE big bore, you won't get it to work with a lightweight hammer unless you can make a balanced valve work for your purpose.... As you go lighter on the hammer, you will need more spring, preload, or travel to compensate to get the same FPE.... If the hammer was way too heavy to start with, the compensation may be miniscule.... If you are struggling to open the valve and fit a lighter hammer, the extra spring force required may make the gun nearly impossible to cock.... As I said, it is all interrelated, and relative to your situation....

Bob

[SpiralGroove]

Hey Bob,
After doing a search, I found that I had asked most of the same questions before - oops!  I now have them bookmarked on my tool bar.

Lastly, because both mods create Momentum and Energy, are  Pre-Load and Hammer Travel perfectly interchangeable?  Hence, if you need less Hammer Travel to reduce hammer strike, just back off pre-load a bit -> exact same thing? 

1) 1/4" less of hammer travel = (roughly) three turns less pre-load?  How proportional are these two factors?

As always, Thank You -
"Sir Bob"  - You will be Knighted using a (PCP) pellet gun "shoulder to shoulder" instead of a sword.