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Crosman/QB Valve Stem Rebuild Starter



 
Our Price: $199.00

Quantity in Stock:3

Product Code: CRQBSRKST
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Description
 
Valve Stem Rebuild components for Professional Rebuild of the Crosman & QB Exhaust valve Assemblies. Can fit many other models and other makers. This kit gives the DIY a good variety of components so he/she can rebuild all the Old School CO2 Crosman and modern QB & TF guns. Made in USA by Mac1. A propane torch can be very helpful to get the brass head to separate from the steel stem. A .2" hole in a steel plate will allow you to drive the stem out of the head when properly supported. The seal fits in the brass head and you use a 1/8" hole in a anvil to drive the head and seal onto the stem. It is a good policy to use a permanent thread locker in the brass head for insurance. Once the head is pressed together it can be trued and faced off to ready it for use. Heat the entire gun up to toasty when you first charge it so the seals will be supple and the pressure will be high. Making sure there is no damage to the valve seat where the seal sits is very important as the Mac1 seals are hard enough so you can leave the gun charged all the time. Getting it to seal initially can be impossible if there is any seat irregularity. Polishing the seat is often required to remove any scratches or abuse. If you use the parts that make for the most reliable repairs imaginable a DIY project can be the best investment you ever made in an airgun. Quality parts last. Your time is wasted when you use inferior parts.
Those that don't have a lathe to cut the seal after install need to spin the head in a driil motor with seal fitted to brass cup prior to assembly to get a reasonable finish on the exhaust valve seal so it will work. Once assembled the DIY needs to be certain the stem runs true and chucking the head and spinning assembly will show you if it got bent on assembly. The stem needs to run true to the head and the thru hole needs to be true to the seat or hard seals won't make adequate contact.
Does not include the steel stem except in the Case of the 6xMKI exhaust valve assemblies. Brass head and seal only on the remainder of the components. MKI early steel stems can be S&W 78 stems if you shorten a small amount (longer tail guides the spring).
This Kit includes
15x Exhaust valve seals(13 small and 2x622)
6x MKI Complete Exhaust Valve w/return spring
6x MKI/S&W/Etc Small head
2x 600 valve head
4x 160/150/180/400 head
2X 622 heads
These components should be able to rebuild over 20 CO2 exhaust valves for under $10 each. For hard core DIYs or Pro Tuners. If you have the skills don't let them go to waste using inferior components.
Crosman & QB Valve Stem Rebuild Procedure-Mac1 HowTo

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