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Old 10-19-2006, 10:43 PM   #1 (permalink)
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Low FPS from a 97 cocker

I currently have a '97 cocker that I bought with a low pressure valve in it.

With the low pressure valve I can't get any thing over 200fps at 400psi. When i get psi over that the fps drop again.

I've been looking for pre 2k valves to no avial, but I was offered a pre 93 sheridan valve. Maybe that would work??

I'm looking for valves in the b/s/t but I need the whole valve assembly, and thus far only valve bodies are offered.

If you have any ideas let me know? Any help would be greatfully excepted.
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Old 10-19-2006, 10:44 PM   #2 (permalink)
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Lower the pressure? If it's too high it will close the valve prematurely.
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Old 10-19-2006, 11:17 PM   #3 (permalink)
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I'd try swapping springs. Some people throw low pressure valves in there and leave the stock springs. The stock valve spring is just too heavy and will close the valve before enough air has gone through (spring pressure closes the valve, air pressure just keeps it closed). You probably want to start with a yellow valve spring (the lightest one in most spring kits) or possibly a green one (second lightest) if the gun's still set up to use Sheridan springs (I think stock '97 'Cockers still were, but someone may have switched to nelson springs along the way). You might have to change up the mainspring as well to find the right balance.

Once the valve spring is lightened up, you should be able to drop the input pressure and see an increase in velocity. Basically, set the rear velocity adjuster all the way out, then lower the input pressure until the velocity peaks (as you go lower, it'll top out and then start going back down - turn the adjuster 1 full turn at a time and make sure you take at least 5-10 shots at each adjustment to let the pressure normalize) - when you find the pressure where the velocity tops out, that's your "sweet spot" - DON'T adjust the reg any more. Go back to the rear vel. adj. and you should be able to dial it in to get a decent velocity. If not, then try a heavier mainspring. Also, adjusting the input pressure will probably require tweaking your LPR (if it's externally adjustable - if it's not, you should be fine).
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Old 10-20-2006, 09:29 AM   #4 (permalink)
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Thanks Wycke, I tried this and thats how I acheved the 200-220 fps I've put light springs in and heavy springs and every in the middle. from my reaseach a stock 97 cockers pressure was still high pressure (900psi) and I cant get the thats with the valving. Should I start mixing the Nelson (pre 2k cocker) spring kit in an attmept to hammer the valve open for longer?
eg. light valve spring, heavy main spring
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Old 10-20-2006, 09:47 AM   #5 (permalink)
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Actually, the one variable I overlooked in air chamber volume. With the smaller front block screw, there probably isn't enough of it. If you could find a low pressure chamber, that should help. Another option that might work is an expansion chamber in the vert asa (to act as an extension of the valve chamber) and move the reg to a remote.
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Old 10-20-2006, 07:03 PM   #6 (permalink)
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Ok I hate to be like this but I have another twist to throw in the loop. (its now a double loop with a roll out) I'm running a CCM Pre 2k mini kit on it. sorry I also for didn't mention its a mini. My bad. Thanks alot Wycke for all the help.
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Old 10-20-2006, 07:14 PM   #7 (permalink)
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Pre2k and Post 2k valves are the same physical diameter, the main difference is that the newer valves have a higher flow rate.

The 97 uses Sheridan springs, unless it's been converted. The LP valves, in a 97 body, need an LP chamber to get enough air, since the early valve chambers are much smaller.

Ideally, for a 97 Sniper, a stock valve would be best. If you want, I have a stock post 99 valve I can send your way. If it works, pay me something for it (or swap me the LP valve). If not, send it back...

Spring balance isn't as important when running constant air. Either way, start with a yellow valve spring and a blue hammer spring.

Let me know.......


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Last edited by Walker; 10-20-2006 at 07:18 PM.
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