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Timing a Blazer

Question:


Timing a Blazer


(a living document - intended as a guide to help fellow PPS owners)


Technical information courtesy Craig Palmer - THANK YOU!
This document would not have been possible without Craig's guidance.




The primary steps are as follows:
  • Set the Stabilizer
  • Set the safety and up trigger travel screw
  • Set the bellcrank and sear
  • Set the Rock
  • Set the velocity
Tools
  • English hex wrench set (SAE)
  • Small flat screwdriver
  • Needle nose pliers
  • Blue loctite
  • ½" wrench
Useful Timing / Tuning Links




Stabilizer
Recommended operating pressure for a 2k Blazer is 350-400psi; for a 1k Blazer 500-600psi. In general, the adjusting screw flush with the Stabilizer end cap is approximately 500psi. For those without a gauge, one turn of the adjusting screw is approximately 100psi. If you are using a different type of regulator, please refer to it's documentation. Lube your Stabilizer monthly, and remember that too much lube will leave oil residue in the barrel.




Safety and Trigger Travel Screw
Remove the grip frame from the Blazer. Safety the grip frame and adjust the up travel set screw (part 78) so there is no play in the trigger. Use blue loctite to keep the set screw from backing out.



When re-installing the grip frame, push forward on the frame while tightening. This will account for slop in the grip frame screw holes. Note that sliding the frame back and forth can change the 4-way timing. A tiny drop of blue loctite is a good idea here.



Set the Bellcrank
With the safety still set and air on the gun, remove the grips and loosen the trigger rod retaining screw (part 56). Move the bellcrank (part 53) back,and the bolt should move all the way back. Move it forward, and the bolt should come all the way forward.



Move the bellcrank back and then slowly forward. Once the bolt hits the forward position move the bellcrank 0.020" (about the thickness of the wire in a twist-tie) forward and tighten the trigger rod retaining screw. The extra twenty thousandths over travel lets the switch stem O-rings (part 10) seal properly in the 4-way cups (parts 7/8).



Use a pair of needle nose pliers to keep the trigger rod from bending when you tighten the trigger rod retaining screw.

Set the Sear
Loosen the sear adjustment screw (part 50) several turns. Remove your air source, cock the gun manually, and air the gun. With the safety still set, slowly tighten the sear adjustment screw; when the gun fires, loosen the sear adjustment screw one full turn. Depending on how much over travel you added in adjusting the bellcrank, you may need more sear (sear adjusting screw: loosen = more sear, tighten = less sear). Test the gun by pulling the trigger slowly: the sear should release before the bolt moves back. Release the trigger slowly: the sear should catch the hammer before the bolt hits the forward position. Use a chronograph to make sure you have consistent velocities when firing slowly or quickly.

Remember: As you increase sear, you're reducing delay (distance between hammer release and switch activation). Consequently, as you decrease sear, you're increasing delay. A Blazer shoots best when adjusting the sear for more delay, but this also increases the chances of short stroking.

If the sear adjustment screw is loose, the gun will fall out of time in a few days of play. We usually spike the threads near the screw or put on a little bit of lock-tite to keep it from backing out.




Set the Rock
Loosen the Rock adjusting screw (part 44) until it turns easily. Air the gun, turn the safety off, and hold the trigger back. Slowly tighten the Rock adjusting screw until the bolt comes all the way back and is flush with the back of the gun. Now tighten the Rock adjusting screw another ¼ turn.




Set the Velocity
Using a chronograph, adjust the velocity screw (part 22) so the gun is firing at 280fps. The velocity screw should be close to flush with the velocity cap (part 20).

Troubleshooting



Ram Bushing
If the ram does not move fairly easily you may have difficulty timing your Blazer. Use a wrench to loosen the ram bushing (part 27) a very SMALL amount. Push the P block (part 30) back and forth to make sure the ram loosens up.

The ram occasionally sticks because we machine everything real tight. Then, when the bushing is tightened down, it kicks off to an angle a little. Eventually the bushing will wear a little and it will no longer be a problem. We build them tight so they last longer.

To 'fix' this problem, clean the oil off of the bushing and ram housing with alcohol before applying a small amount of blue loctite on the bushing. The loctite won’t break free if you get the part clean enough. After the bushing wears a little it can be tightened back down. Other options include sanding the internal ram plunger or opening up the bushing.





Trigger Drag
We test trigger parts for drag while building your gun, but some people decide to install there own parts. So be on the look out if your one of these people. The only way to find the drag is by disconnecting the parts from each other.

To test for drag: Disconnect the frame and springs and hold the frame vertically. The trigger parts should move by gravity alone.


These are common points of drag:
  • Trigger rod to trigger (parts 60/61)
  • Black Trigger rod retaining hat is too tight (part 58)
  • The hole in the bellcrank is too small (switch rod and trigger rod retainer) (parts 51/57)
  • Bellcrank rubbing on the side of the sear
  • Bent rods (parts 51/61)
  • Switch rod rubbing on the sear pin (1K blazers only) (parts 51/45)
  • Trigger return spring rubbing on bellcrank (parts 53/71)
Bolt and Barrel Fit
Occasionally (more often with tight bore barrels) the bolt will stick or jam in barrel. Move the bolt back and forth, and slowly rotate the barrel to find a position where the bolt does not stick in the barrel.

If you have a matched barrel, it may be necessary to shim the barrel with tape to keep the bolt from sticking.





Cyclic FPS and Non-Cyclic FPS
Comparing cyclic velocity to non-cyclic velocity can help you determine if you have a delay problem after timing your Blazer. Fire the gun normally (cyclic) and note your velocity. Next, hold your thumb against the P Block (part 30) to keep the bolt from moving back (non-cyclic), and fire the gun again. If your non-cyclic velocity is higher by more than 10fps (on average), then you've not timed the gun with enough delay. Keep in mind that paint can cause variances as high as 30fps between shots.


 
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This question was added to our store on Wednesday 11 May, 2011.
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