Lessons Learned Installing Huma Regulator in FX Wildcat MKII

[grandspud]

I recently installed a Huma regulator in my FX Wildcat MKII. The bad news is it didn't go smoothly as seen in Airbuks' YouTube video. The good news is there was no irritating background music during my install as there is on that same video (also I finally was successful after several days of research, testing, and scouring airgun blogs.)



While the video is pretty much correct and helpful, it did nothing to guide me through the numerous complications, unexpected problems and detours I encountered along the way.



Over the next few days I will add posts each detailing a lesson learned (I have about 10 of them.) It is my objective to share my experiences in the hope it will assist other Wildcat owners doing this worthwhile upgrade.



*** I am not an expert on any of this stuff and may make incorrect conclusions or make incorrect statements. If you see any of these please respond. I am not the sensitive type and would appreciate your insights so I can learn even more. ***



Lesson #1 - BUY A SPANNER WRENCH for $15

To remove the old regulator and install the new one, you will have to remove the air tube from the frame and then unscrew the air tube's end cap. The on-line instructions I found all showed this being done by inserting a pin of appropriate size into each of the two holes in the air tube's end cap. The instructions then show a pair of pliers being used to simultaneously grip both pins and rotate.



The problem I encountered doing this was that one of the pins "leaned" during the attempt (yes… pins were correct size and fitted deep and tight.) I found that because the two pins were not connected to each other they could move independently. Considering the inexact, crude grip regular pliers will have on the pins, more force may unintentionally be applied to one pin than the other pin. My end cap was quite tight and after carefully trying to rotate the cap with pliers, one of the pins leaned over.



I ordered a 3mm spanner wrench (prior I ordered a 4mm spanner wrench as shown on the video which did not fit my 3mm holes) on Amazon for $15. It arrived in two days and worked extremely well. Money well spent!



Because the two pins on the spanner wrench are physically connected to each other, one pin cannot go off and "do its' own thing." The two pins must work together, like two oxen in a yoke. This insures two things: 1) both pins always exert equal pressure on both holes and work as a team, and the pins can never "lean over" because they are welded to the wrench handle.

 

[Bigragu]

Good tool to invest. I use the same one E. Rowe uses in one of his vids. I’m actually going to invest in a couple more sizes as these tools are awesome. Yeah, using those pins as leverage in that Airbuks video is bogus. I, too fell for the wrong info they presented with 4mm pins. Best to use not only the right tool, but good tools!!

 

[grandspud]

Lesson #2 - What to do if You're an Idiot and Installed the Regulator Backwards

Yes… I knew the correct orientation for the regulator when inserting it into the back of the air tube. The part with the BAR markings should go in first so it will be on the high-pressure side of the air tube. I guess I was too excited (and old) that I screwed it up.

I discovered my error when I eagerly charged the reassembled Wildcat to 230 Bar and headed for the Chrony. Boy was I perplexed when the gun only made a click when pulling the trigger. After about 6 hopeful pulls of the trigger (thinking something needed to settle in) I admitted something was wrong.

About an hour of brain gymnastics brought me to the realization I put the thing in backwards. So, I removed the stock and slightly loosened the brass bleed nut on the side of the receiver. NOTHING… there was nothing to bleed! I then figured that the 3,300 psi sitting in the air tube high pressure side could not go backwards through to the Huma regulator to get to that bleed nut! Boy, I thought I was screwed then with a forever pressurized, usless air rifle.

Then I remembered watching one of Ernest's videos where he bleeds a rifle using the brass bleed nut and stated something like, "… you don't have to loosen the tube pressure gauge to let the air out, you should use the bleed nut…" Armed with that recollection I decided to do just that, loosen the Wildcat's air tube gauge.

Now… the nut on the Wildcat's air tube gauge is kinda' recessed. You have to have a really, really skinny 11mm wrench to get between the tube and gauge just to get a hold of the darn nut. All my wrenches were obese fatties so I had to go off in search of a scrawny, open end wrench. 

I finally succeeded in bleeding air through the gauge. Following that, I successfully put the regulator in the correct way and reassembled the Wildcat. The only problem with that instead of solving the problem, it led me directly to Lesson #3! 

 

[idaho_varminter]

Just to throw a monkey wrench into the works, evidently the end cap on the tube has now changed, and has a nut welded or formed on it. That’s the reason why Ernest’s 2.5” plenums are now nowhere to be found. With the change, his plenum does not fit properly any longer. I reached out to him on his YouTube channel, and he told me redesigned plenums are coming soon. 

 

[Eaglebeak]

The name Spanner Wrench doesn't make any sense. Where I come from a spanner is the same as what you people call a wrench. So it's the same as calling it a Wrench Wrench or in English, a Spanner Spanner. Surely they could think up a better name.

 

[Bigragu]

As the title clearly states, this tread is about a regulator install on an MK2. End cap and adapter to block are two separate pieces sealed by o ring and dowty seal

 

[markT]

I had to get a tough end cap off in the past. Those spanners in soft Aluminum. Nope. 

Ordered a split shaft collar and used a pipe wrench.

worked perfectly for less than $5. No marring, slipping etc. 

 

[Yo]

Next time if you need to degass you only reconnect the fill hose then crack the tank open till it clicks then shut that tank and SLOWLY! unscrew the bleeder just a hair till it barely hisses out then STOP let it hiss SLOWLY keep everything connected to the gun and go make a sandwich have a beer.The air should all piss itself out. You want it coming out SLOWLY.

 

[grandspud]

Lesson #3 - Holy Crap Batman… My Gun Will Not Stay Cocked

Well, after getting everything reassembled again and the gun charged to 230 BAR I hustle back to the Chrony. I pull the cocking lever all the way back and it will not catch! 

Spending a few more hours researching I find Ernest Rows video "FX Masterclass : Wildcat MkI Reassembly." In that video Ernest states, "The Wildcat is one of the hardest to learn because there is so much alignment that needs to be done." How right he was. 

What I concluded after watching the entire video is that air tube is really the backbone of the entire rifle. Those four screws you tighten on the clamps that surround the air tube are not there to hold the tube in place. They are there to give rigidity to the rifle frame and keep everything solidly aligned. 

When I clamped my air tube back to the frame I paid no attention to how the cocking rod, trigger rod, and everything else were situated. Those things really move around when the air tube is not secured and because I did not know to be careful, things were not precisely positioned when I locked them in place.

Well… I decided to again loosen the air tube clamps and dove right into another problem and Lesson #4.

 

[grandspud]

Lesson #4 - Why the Heck are These Air Tube Clamp Screws so Hard to Turn?

As I left you last time, I was in possession of a fully charged, reassembled, incorrectly aligned Wildcat MKII. So, I decide to do what any adventurous airgunner would do, dive back in and correct the problem.

I removed the stock and started to loosen one of the air tube clamp screws so I could begin repositioning everything. Dang… that screw is stuck!

I got a longer allen wrench and carefully increased pressure… then more.. then more… then finally it came loose. 

I contemplated this for awhile and finally the brain kicked in. Earlier, when I screwed tight these air tube clamp screws there was ZERO-PSI of pressure in the aluminum air tube. Now, as I tried to loosen the screws, there was 3,300-PSI exerting its' force inside the tube walls. The tube had expanded when pressurized and therefore the clamp-to-tube connection was way, way, way tighter.

The solution, of course, was to again bleed the pressurized air from the tube before I tried to loosen the other three screws. Amazing… they came off quite nicely and without problem.

Well... off to Lesson #5 

 

[exsquid]

Appreciate your comments and anxious to see the rest of the learning curve explained. This will help countless people do exactly the same thing. Thanks for taking the time and effort to put this together!

 

[Guest]

Don't own an FX but subscribing for notification -- good food for thought applicable to other situations/guns. Thank you for posting.

 

[bearair]

Glad you got it sorted out. Following along as well.

 

[MoeHofer]

Great stuff! Thanks for posting all your "interesting finds"!

 

[Ctkny]

 

[Greenarrow]

These are great lessons! You learned so much in one experience. Looking forward to the next lessons learned. Probably gonna save me from some headaches one day. I already installed my HUMA and didn't have the issues that you have faced. Thanks for sharing!

 

[Bigragu]

Grand spud- lather the threads of those four bolts with anti- seize. Just trust me on this one. 

When you get everything all figured out. Take a mechanical pencil and run it along the edges of those clamps, both of them, front and back, allaround, before you reinstall the stock. These marks will help you later on 

grab some blue lock tight and apply it to the threads on the two bolts that secure your scope rail I bet you if you took a 4mm Allen to check tightness on those you will see how loose they are.

 

[grandspud]

Brilliant idea the Yo! I'm putting that one in my memory file for use in the future.

Thanks.

 

[grandspud]

Lesson #5 - When You Align Everything… ALIGN EVERYTHING!



Well, after once again loosening those air tube clamp screws I aligned everything (yeh, sure, right…) and tightened her back up. I wasn't going to be thwarted again so I cleverly checked that the cocking mechanism and trigger were functioning properly before proceeding to the pressurizing task. Success!



I don't like holding the Wildcat without the frame sitting inside the stock. That trigger rod scares me a bit and I don't want an AD. So, before going to the chrony again I did just that.



Now I knew I'd have to have access to the hammer spring nut at some point for tuning. I would normally just set the works inside the stock without securing it down. However, because I had only a few minutes to try it out before running an errand, I decided to go ahead and secure stock to receiver with the screws (I've left the gun sitting in the frame unsecured before and forgot the screws were out. I grabbed it the next day to take a couple shots and was lucky to catch the upper as it fell out of the now vertical stock.)



To my surprise it was impossible to get both screws in. The holes in the stock were no longer aligned with the receiver's secure points. I could get one in, but then the other would be on an angle and not able to engage the threads properly.



Off again to Ernest's video. Indeed, he makes of point of warning aspiring airgunsmiths about just this. In the video the last, precise alignment Ernest does is the stock screws. He has the Wildcat laying on its side, has everything aligned, then he very gently angles the receiver just enough that he can slide the stock on. He actually inserts and gently tightens the stock screws to make sure it is a perfect fit. Only after all this does Ernest gently slide the stock back off and tighten the air tube clamp screws.



Ok, I know the procedure now. Again bleed the pressure, again loosen the air tube screws, again align stuff… only this time don't forget to check stock-to-receiver attach points.

 

[grandspud]

Lesson #6 - Keep Learning and Tinkering... the End Results Will be Worth the Pain

I've attached a photo showing why the Huma Regulator for the FX Wildcat MKII (AMP Replacement Version) is worth the effort. There will be almost no volume loss of high pressure air while at the same time gaining a HUGE increase in Plenum Air. The total top-to-bottom length of the AMP is slightly taller the that of the Huma (excluding Huma adjustment thingy sticking up.)

 

SIDE NOTE... Look at what I lucked into two days ago while getting my Great White tank filled at Joe Brocato's Expert HPA shop. It had just arrived so I snatched it up, took it home and dressed it up a bit with Donny FL Ronin and Hawke scope! (.22 compact). OK... back to topic and lesson #7 coming up.