I need to know what the original Impact's valve stem seal diameter is. If anyone has an original valve stem assembly or seal laying around could you please measure the outside diameter of the seal. I understand that the new MK2 seals are 7.2mm, with the 6.5mm integrated valve seat. Did the seal diameter change with the new seat opening? Can the original Impact's valve assembly rod and seal work with the 6.5mm valve seat?
What's the original Impact's valve seal diameter?
- Thread starter Airgun-hobbyist
- Start date
I don't think I'd polish a valve seat because you could get the sealing surface uneven and have a leak. I would change the Delrin seal to PEEK for longer life and cut an angle on the windward side for better air flow. Then shorten the rod spring and beehive the end so that it seats where the rod meets the valve assembly rather than right behind the Delrin seal. This should help airflow a little.
Here's a quick sloppy illustration.
Here's a quick sloppy illustration.
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Going from a polished 6mm seat to a 6.5mm seat was worth an additional 10 fps. She's running a consistent 977-980 FPS @ 160-163 bar now with with sorted JSB 50.15's.
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