Gun Block - Graco 255828 Operations & Parts List

Repair
2. Thread throat assembly by hand into gun block. Use
throat wrench to tighten.
Front impinger should contact throat surface about
1/2 to 3/4 turns from actual seating of throat to gun
block surface. This compression creates the inter-
nal seal within front portion of chamber.
3. Assemble front impinger and pattern control tip.
Insert front packing into pattern control tip. Place
front impinger over end of front packing. Place pat-
tern control tip o-ring into groove on pattern control
tip.
4. Engage safety stop, see Safety Stop on page 7.
Press and hold trigger then hand-tighten pattern
control tip into gun block.
5. Release trigger to align components then press and
hold trigger. Use 10 in. adjustable wrench to tighten
pattern control tip about 1/8-turn. Release trigger.
Repeat until the pattern control tip is snug on the

gun block.

If after finishing step 5 the valving rod is not pro-
truding at least 1/64 in. from the end of the pattern
control tip, the pattern control tip will need to be
removed then steps 4 and 5 repeated. The pattern
control tip will need to be tightened in 1/16- or
1/32-turn increments.
Pattern
Control Tip
20
Gun Block
In severe cases of material buildup, it may be necessary
to remove the gun block and soak it in gun cleaner.
1. Follow Pressure Relief Procedure, page 12.
2. Remove the pattern control tip and front impinger;
see Pattern Control Tip, page 16.
3. Remove coupling block and check valves; see Cou-
pling Block and Check Valves, page 18.
4. Remove rear impinger and throat; Impingers, page
19.
5. Remove gun block mounting screws.
Mounting Screws
6. Remove resin (rear) seal screw and resin seal
o-rings.
312888D