how to repair pump cup on sheridan blue streak

This setup became known as the “Steroid Valve” and seems to have influenced the valve designs of many modern airguns.īenjamin/Sheridan/Crosman began to systematically weaken the powerplant components, perhaps as Tim thinks, to cut costs, or maybe to discourage tinkering and thus reduce liability (my thought). I took some samples home and ended up redesigning the valve stem, head, and valve seat to give more power with less pumping and a lighter striker spring.

Later, Tim was a bit down because he could no longer get decent valve-heads from the factory, and was resorting to reworking older takeoff valve parts, which were harder. I didn't really like or need the extra pumps. I liked it because power was up over stock after around 4 pumps, and full stock energy of about 13fpe came in as low as 7 pumps on mine …. I had Tim do my Blue streak, and it was more powerful, giving around 17fpe with some hard pumping. When I met him, he was rebuilding older Sheridans and installing whet he called his “14pump” tune … it allowed the gun to hold and discharge up to 14 pumps, rather than the normally accepted 10 pump max many owners used. There is an Option for Pre-78 Benjamin as well which will service the early guns with the Benjamin cup that pops over a 1/4' center shaft.Mac1 does know how to get way more power from the older Sheridan and Benjamins. If you have early non-rebuildable Piston, get the Stainless Steel Piston head as well. If the Pins don't drive firmly into front plug consider getting the Steroid Steel Front Plug. Includes Pump Cup, lever link rivet, felt bumper, link pivot, Secret Sauce lube & spring pin. The round rivet should be primarily bucked from the large side while the Mac1 Keyed rivet should be first bucked on the Keyed side.

That means no Lube which translates to rusty valve springs and fouled exhaust from rusty muck.įactory round rivets tended to turn if they were not bucked properly and an oversize Round rivet is what Mac1 sells so the rivet will fill the bevel and engage the lever adequately to eliminate rivet spin. Early guns had a bad rivet arrangement that needs to be upgraded to 1/4' rivet on link rather than bushing between link and rivet. The lever needs to be drilled and beveled 1/4' on one side and a newer round rivet fitted on the earlier models. You will not see it till you take the rivet out. It wasn't a very robust design and most failed. On Pre-'62's often the lever link bushing is toast. Make sure you mop all the goo out of the front end/inside tube packed against the valve face. This is what you need if the Pump group of your Post '78 Benjy or ANY Sheridan has been neglected and you need to put all soft and hard goods in place to get a fresh start. Available in Round (early)or Keyed Rivet(late/Post'76).

How to repair pump cup on sheridan blue streak