Huma regulator dimensions for M-Rod.

Does anyone have the dimensions for the Huma regulators? I want to get one for a 177 M-Rod. I would like to know the size of the basic regulator without the plenum, and the lengths of the available plenum.
I scoured the web looking for the physical dimensions to no avail.
Also if you just happen to know if any other airgun might have the same diameter and similar form but with a different plenum length.
Thanks in advance


Hunter

The .177 and .22 are the same. I have one for a .25 in my Synrod, it has about .3" longer plenum than the smaller caliber version. They also have a longer plenum, the XXL.

Hunter,

Did not see this earlier - fortunately I have some detailed answers from data I collected on this over the years; probably more than want but here is all of it:

I have Huma regulators in multiple.22 and .25 Marauders.  Over the years I have purchased the various .22 and .25 plenums with the built in gauge port, as well as the .25 and XXL tuning plenums that are used with (or without) the existing gauge port, and tested multiple configurations of these.

The plenums with the gauge port can be modified with a Dremel to hog out unneeded aluminum, as the material for the gauge port forms a full “ring” inside the plenum for easy manufacturing - doing this will add about 6ccs of plenum space.  See the picture at the bottom to understand what I am referring to here (and no comments about how ugly I made the part – it is functional  ).  I also attached a picture showing the XXL plenum with a gauge block, the .25 integral plenum, and the .22 integral plenum for relative comparison.

The plenums have the following lengths and volumes (as measured by the water that they hold, measured up to the threads that the regulator mounts to, in a graduated cylinder):

.22 integral plenum: ~11 ccs, ~17 after mods, 56mm long (not counting regulator)
.25 integral plenum: ~16 ccs, ~22 after mods, 70 mm long
.25 tuning plenum: ~16 ccs, 50 mm long
XXL plenum: ~28 ccs, 85 mm long
Gauge port: ~2.5ccs, ~8 after mods, ~35mm long (if I recall correctly, as it is in the gun now)

Most valves probably have around 5 ccs of volume within them, thus – assuming we mod for more plenum space – we have the following approximate plenum sizes in the different set ups:
.22 integral regulator:  ~23ccs, 56mm long (not including the regulator)
.25 integral regulator:  ~27 ccs, 70 mm long
.25 tuning by itself:    ~21 ccs, 50 mm long
.25 tuning with factory gauge port: ~24 ccs, 85 mm long
.25 tuning with modified gauge port: ~29 ccs, 85 mm long
XXL tuning by itself:    ~33 ccs, 85 mm long
XXL tuning with factory gauge port: ~36 ccs, 120 mm long
XXL tuning with modified gauge port: ~42 ccs, 120 mm long

There is probably another cc or two that comes when the regulator is threaded into the plenum, but all these values are good for comparisons to each other.

Unfortunately the regulators themselves are currently all installed; I never accurately measured them before.  But I estimate that after screwing the regulator into the plenum (one is required), it adds ~10mm in length to the regulator assembly, at full plenum diameter, and then has a central section ~25mm long and ~15mm in diameter.  Someday when I have one out I will measure it accurately.

I don't have a .177 Marauder so have no direct experience with it, but I can tell you this: if going for anything related to "higher power," in every case I have found that the efficiency gains from having a larger plenum have yielded as just as many and often more usable shots despite having lost high pressure air space from the longer regulator set up.  Clearly the XXL plenum is not going to deliver that for you in your .177as it is overkill, but I would not be surprised to see the .25 integral plenum performing that way for you if you are going for 20 FPE or more out of your gun.  This happens because these don't really have very large plenums to begin with.  But if you are going for 12 FPE the .22 plenum should do very well.

I am not sure what you are asking about on the adjuster fitting into the gauge block. If you use a gauge block, it goes between the valve and the regulator plenum as shown in the picture below.

I really don't think there is much chance for the "stem" on a Marauder Huma regulator to fit into the gauge block.  Here are pictures of two Marauder gauge blocks - the one on the right is factory, with a central hole that measures only abou t9.5mm in diameter.  The one on the left is one that has been machined out for more air volume (this picks up about 6ccs over the stock block), but the effective central clearance diameter only increases a small amount - but it does add some "depth clearance" that might be useful for you.  In this case, it is ~11mm deeper than the edge of the stock block.

Depending on the dimensions, it might be best to have someone make up a custom "hybrid" plenum that includes that modified gauge location in the plenum for the regulator, as one piece.  It is probably an expensive way to go, but it would work.  Alternately you could use a .22 cal integral plenumand have a custome plenum spaced made for between the reg and the valve.  And lastly, depending on the dimensions, you might be able to use the giant XXL plenum and forgo the gauge completely, assuming that the o-ring still seals on the front side of the gauge port hole in the tube.

Hunter,

I understand what you are trying to do.     It is what I thought crosman did to get a little more power out of the SAM.   After reading a HAM article, think they just made the valve shorter and made a spacer.  Similar to what they did on the Fortitude.

If you are just looking for a modest power increase, this may work.   For higher power, I think making a "bleed hole bridge" from a gauge block, and shimming to get the Huma w/gauge hole to line up, or just another gauge block w/tuning reg, would work.   I'll be watching along.      A modified SAM may be in my future. 

Yours is the 1st re-reg of the F&T I've seen.  Unique in trying to keep the same configuration, too.    Is it a 177 or 22?

The stock 0.140" porting will be good for 177.    

Just finding this thread ....

I've been using the HuMa "Universal" regulators for years now with M-rod Reg conversions.
The O.D. of reg is turned to 1.050" and o-ring grooves cut for 118 rings.
Gauge block majorly opened up as others have shown with .177 & .22's generally not requiring more plenum volume. ( Well at least.22 up to @ 30 fpe ) with .25's requiring a spacer to increase volume.
* Using Universal regs you MUST drill a vent hole once Regs position within tube is established.

Quote from: Motorhead on May 09, 2020, 11:40:18 AM

Just finding this thread ....

I've been using the HuMa "Universal" regulators for years now with M-rod Reg conversions.
The O.D. of reg is turned to 1.050" and o-ring grooves cut for 118 rings.
Gauge block majorly opened up as others have shown with .177 & .22's generally not requiring more plenum volume. ( Well at least.22 up to @ 30 fpe ) with .25's requiring a spacer to increase volume.
* Using Universal regs you MUST drill a vent hole once Regs position within tube is established.

Thanks Scott. I will use the 17/22 Huma on the FAT-Rod using the existing vent port. This reg goes downwind from the gauge block.
Then transplant the Benjamin reg from the FAT-Rod in the 25 M-Rod, I wasn't sure about drilling the vent, but if this is okay,  then that reg will go upwind of the gauge port on the 25 M-Rod. Is that right?

Hunter

With your mixing and matching ... ONLY THING to wrap your head around is that Regulator has an atmospheric vent that must be able to see/sense the air outside of the gun.   If the stacking of parts and the o-rings that seal it to the tube I.D. BLOCK the vent ( say too gauge hole such plenum equipped HuMa ) Then a hole ( Only @ .040" required.  Smaller is better ) must be drilled in the side of tube so it lands in the space where vent of Reg can vent out. * They don't need to be exactly aligned just occupying the same @ placement.  Air can go around corners and threw clearance gaps W/O issue.

Wow! Ken, Alan, John and Scott, Thanks guys. I really appreciate your advice. 

The FT tube has a vent in the same location as the gauge port on the standard tube. I plan to use the existing vent and gauge port and just replace the Benjamin reg with the Huma.
I may end up needing a custom length plenum.
I hope that makes sense.

I won't start on the 25 for a while, I've been re-reading the 40-40 thread from a couple of years ago.  I guess that will be my next adventure.

Hunter