hammer spring mod

ive been reading through all the tuning information available here most of it is straight forward and similar to gas flowing engines one question i have is where the washer is placed to increase the hammer tension,and what size this washer can be from what ive read it appears the washer thickness is about a quarter of a inch

[Gene_SC]

Did you look in the Library Ian? CDT has some info there that may help.

Gene

[mikeiniowa]

A small OD 1/4 inch washer will fit or a #10 machine screw washer, keep stacking until it won't cock then back off one......it's hard on the end of the valve stem, I perfer to go with a lighter spring in the valve.

[IJL]

Ian, MikeinIowa is absolutely right and the shim goes straight under the hammer spring, but I doubt you will need to shim it or mod the valve. Some of these QBs will go well over the uk limit with just a good porting and polish so take care!(Make sure you know what weight pellet carries the most energy, they vary!) This is the guide from CDT that I started with. It got my PCP converted QB to almost 40 fpe till I worked out how to slow it down again!

http://www.gatewaytoairguns.com/library/Charlie’s%20QB-78%20Tune.htm

Ian