Regulated .177 M-rod build about to get started.

Here's a few photos I took a couple of years ago while I was modifying my valve for regulating a 22 Rrod. I don't remember everything as it unfolded by I think you'll get the jist of what I did.
I did Loctite or cement the velocity screw in place before I opened up the exhaust. You can see the adjuster in the port.


I then rounded off the inner edge of the exhaust port to help with flow hopefully

I enlarged the intake port to .280,

The inner sleeve of the 25cal valve could be removed at the time to allow for more volume in the valve. The drill bit's point is resting on that sleeve.

I opened up the inside of the valve further with a 1/2" bit. Care must be taken here not to go to deep and get into the seat of the valve.

This is after opening up the valve body to 1/2". You can see the seat in the bottom.

Anyway, hope this helps. I always enjoy pictures of what I or someone else is trying to explain.
There is another modification that can be done to the intake cap other that drilling it out to .280. I don't have that photo but it's just drilling a couple of 1/8" holes parallel to the .280 hole to increase flow even more.
JImmy

I did to but I didn't remember what to. That's getting really close to the valve seat also. Probably not worth the risk if all you have is a drill press. Got to love the Marauder possibilities.
jimmy

Im putting a Huma regulator in my gen 2 .177 mrod. I want to shoot jsb 10.34gr pellets at or close to 900fps. Any I dea what pressure I should set the regulator to? 

Its the Huma that you take the guage port out and screw the guage into the regulator

Having set up many dozens ... the .177 guns with a 20 gram hammer and a lighter poppet spring work GREAT at @ 1600 psi set point.

This will provide give or take 80 regulated shots with 10.3's at @ 900 fps.



Proven to work over over & over again.



Good luck

I put the Huma regulator in I also put a larger transfer port in a lighter spring in the valve a lighter hammer and a lighter hammer spring when I filled my Marauder the Gage did not show the regulator pressure of 1600 PSI the gauge read zero something's not right any ideas???

Did you accidentally change the reg. setting when you installed the small screw in the end of the reg.? Maybe bumped the setting down when you slid the reg. in? I had the same thing happen to me, accidentally backed off the setting when I installed the screw. Also, make sure the small o ring is not smashed shut under the gauge port.

" I put the Huma regulator in I also put a larger transfer port in a lighter spring in the valve a lighter hammer and a lighter hammer spring when I filled my Marauder the Gage did not show the regulator pressure of 1600 PSI the gauge read zero something's not right any ideas??? "

Thinking you DO have air in it., you smashed/squished the seal which is no blocking off the air passage to the gauge?



John

I degas it and look at that tonight. Appreciate your help !!!!!

gregory177,

Try to spin off your pressure gauge BEFORE you degas and see if the o ring is smashed. If no air beyond regulator the gauge should come right off. Then see if air is leaking out gauge port hole. If not, you probably backed off your reg set point.

Dennis

I slowly turned the guage and it hissed out air. As I played with the striker and hammer adjustment the gun leaked alot out the barrel. I think I must of done something to the valve for it to leak like that. I will take it appart again and see whats going on. Thanks.

Set the reg at 1600. Lightweight hammer. Lightweight vavle spring. Swap out the hammer spring with a Hill 255 or 262. Personally, after doing this I would leave everything on the rifle stock except swap out the hammer for a 20-25gr aluminum hammer. Works better than a reg and you should get over 100 12fpe shots filling to 3000. More if you fill to 3100.

Port size is only part of the factor that determines energy output, the primary and most important is valve duration, which can be controlled by hammer weight, hammer travel, and the hammers spring rating...I'd personally open up any pcp's port to roughly 75-85% of the rifles bore size when going regulated, when going beyond 75% you typically want to start to oblong the barrel port so that the width of the port doesn't exceed 75%~


The next most important factor is regulator set point, which can be greatly reduced with much larger ports, which allows much more head room for shots while on the regulator. 



Its neither counterintuitive nor necessary but certainly is recommended provided you know what you're getting yourself into



GL

-Matt