Poppet Modification on 392 ?

[wll2506]

If I take the poppet out of the valve and put a 45 deg angle on the side facing the seal area, what kind of velocity will I gain because of better air flow around the poppet seal area, is it worth it !

Next week or so I will be replacing the O rings, and maybe putting in Steroid linkage. I want this to be the last time I take this gun apart for a long while .... so hence the question, a gain of 4 or 5 FPS would be very welcome, I’ll take anything I can get without having to go to machinist school to do it !

Thank you guys in advance,

wll 

[RBQChicken]

4 or 5 fps?  That's not enough to bother with. You'd never notice that small an increase in fps.  As for the steroid pump arm linkage, here's a thought (just an idea):  wait until you need it.  That is, use the gun as is, and if you notice wear after awhile, then replace the OEM part with the steroid.  You may never need to do it for a long time.

By the way, I really have been enjoying following your posts on this project.  Thanks!

[Blunderbuss]

I don't know. But if you're going to be pumping that gun 8 times in cold weather or more than 8 times make sure you get some extra check valves exhaust valve. The Rubber seal will get blown out very quickly pumping a gun more than 8 times. Ask me how I know.  You can replace it with Delrin.. may need to mod the inside of the valve so it seals properly. Or try and replace the ruber with delrin ,this will allow you to pump more than 8 times with worry about the seal failing..... it was more work then its worth in my opinion ,fun to work on though  .. Also you're going to need to use the factory spring and don't cut down the inlet popit so the Delrin can seal .good luck...

[wll2506]

4 or 5 fps?  That's not enough to bother with. You'd never notice that small an increase in fps.  As for the steroid pump arm linkage, here's a thought (just an idea):  wait until you need it.  That is, use the gun as is, and if you notice wear after awhile, then replace the OEM part with the steroid.  You may never need to do it for a long time.

By the way, I really have been enjoying following your posts on this project.  Thanks!

Yes, I understand, but since I have the gun apart, that mod will take me about 3 minutes to do .. 4 or 5 fps will give me a few more fpe down range and Ill take it !! Remember I'm looking at the fps and fpe with heavy pellets only ... a few fps mean a lot with fpe with heavy pellets. 7 or 8 fps would give me about another 1/2 fpe at 45 yards, may not sound like much but it may be enough difference to bring an animal down or not ... I don't know.

My intent with this airgun are most likely different from most folks ..... I will not plink cans with it (have a Daisy 880 for that, what a great fun gun), will definitely not do any target shooting with it .. the gun has one main purpose and one secondary purpose, the main one is to collect food if the need arises, that is small game - rabbits, squirrels, pigeons,  the second one is to have the fpe at around 45 yards to take down bigger game should the need arise, as in Coon, Possum, Rock Chuck and the like.

wll

[wll2506]

I don't know. But if you're going to be pumping that gun 8 times in cold weather or more than 8 times make sure you get some extra check valves exhaust valve. The Rubber seal will get blown out very quickly pumping a gun more than 8 times. Ask me how I know.  You can replace it with Delrin.. may need to mod the inside of the valve so it seals properly. Or try and replace the ruber with delrin ,this will allow you to pump more than 8 times with worry about the seal failing..... it was more work then its worth in my opinion ,fun to work on though  .. Also you're going to need to use the factory spring and don't cut down the inlet popit so the Delrin can seal .good luck...

I have ordered parts from Crosman and have gotten two different types of poppet valves ..... the brass ones with the rubber on the contact point and the solid Delrin one, I much prefer the solid Delrin one. I will shape the Delrin valve like the brass one that was designed years ago. That shape I expect allows for faster air flow around the circumference of the valve and into the air port.

wll

I just checked my first order and it also was brass poppet valves. I will call Crosman tomorrow and hopefully get the correct ones sent, I really want current production !

wll

[Blunderbuss]

I have ordered parts from Crosman and have gotten two different types of poppet valves ..... the brass ones with the rubber on the contact point and the solid Delrin one, I much prefer the solid Delrin one. I will shape the Delrin valve like the brass one that was designed years ago. That shape I expect allows for faster air flow around the circumference of the valve and into the air port.

wll
[/quote] 

sounds interesting .so  will the solid delrin fit in or do you have to mod it ?.. and do you have a part# .. the rubber one is the Achilles heel of this gun . Just replacing that rubber exhaust seal would make this gun so much better allowing one to pump it more than 8 times and make it more powerful .. I'm sure once accomplished the gun wood experience premature wear on the linkage but like you said you just want it for a backup hunting gun..so I think your mods are going to be a good thing ..keep us posted

[Robert 5mm]

The current poppet is the delrin

[wll2506]

The current poppet is the delrin

Robert, to get your speed after your valve mods, did you add a Mac1 billet lever arm, lever link and a adjustable piston ? ...... just wondering ?

wll

[Motorhead]

Which ever design opens easiest ... thus leaving more hammer hammer energy to create poppet lift and the longest dwell exhausting the most air.

[Robert 5mm]

The current poppet is the delrin

Robert, to get your speed after your valve mods, did you add a Mac1 billet lever arm, lever link and a adjustable piston ? ...... just wondering ?

wll

No, just the 3 step valve mad plus the chamfer on the air port

[wll2506]

I don't know. But if you're going to be pumping that gun 8 times in cold weather or more than 8 times make sure you get some extra check valves exhaust valve. The Rubber seal will get blown out very quickly pumping a gun more than 8 times. Ask me how I know.  You can replace it with Delrin.. may need to mod the inside of the valve so it seals properly. Or try and replace the ruber with delrin ,this will allow you to pump more than 8 times with worry about the seal failing..... it was more work then its worth in my opinion ,fun to work on though  .. Also you're going to need to use the factory spring and don't cut down the inlet popit so the Delrin can seal .good luck...

I have ordered parts from Crosman and have gotten two different types of poppet valves ..... the brass ones with the rubber on the contact point and the solid Delrin one, I much prefer the solid Delrin one. I will shape the Delrin valve like the brass one that was designed years ago. That shape I expect allows for faster air flow around the circumference of the valve and into the air port.

wll

I just checked my first order and it also was brass poppet valves. I will call Crosman tomorrow and hopefully get the correct ones sent, I really want current production !

wll

Just called Crosman and the very nice customer service lady will be talking to manufacturing to find more about this.. They may be using stock that is on hand for right now, but I will will find out more when she emails me.

wll

[Jonah]

4 to 5 fps is not going to do much. You are probably getting that much spread over a string of shots, say 10 shots anyway. For 4 to 5 fps, not worth the effort.

[wll2506]

4 to 5 fps is not going to do much. You are probably getting that much spread over a string of shots, say 10 shots anyway. For 4 to 5 fps, not worth the effort.

Yep, that is true, but if it takes about three minutes to do and if I get that 4-5 or maybe more velocity, it will be worth it to me.

wll

[wll2506]

The current poppet is the delrin

Robert,

That is what I thought too, but just spoke to Crosman today and the gentleman on the line said the brass valve is the current one used ... I don't think so. My 2 month old 392 came with a Teflon poppet valve NOT a brass one !!

HUMMMMM !

wll