Author Topic: Maximus Prime (Read 21109 times))

FuzzyGrub · « **Reply #60 on:** March 03, 2017, 07:24:42 AM »

Looking at the valve, that 3rd trigger screw relief lines up with the thinnest part of the valve. The thread length will be critical.

Does anyone have the maximus valve inside measurements? Specifically exhaust and pocket behind poppet? Need to open the prod valve for the lower pressure range. I found a spring in my stash that is weaker than prod, but seems the same as the disco. I'm thinking 0.120 - 0.140" on exhaust. The pocket is more limited.

3rd valve screw: It looks like if I used a larger head disco valve screw it would cover that slight offset screw hole on the bottom. Dremeling that hole is going to be a test of my skills. It will also require making the flat on the valve a little wider.

JohnnyD143 · « **Reply #61 on:** March 03, 2017, 08:32:27 AM »

Quote from: FuzzyGrub on March 03, 2017, 07:11:18 AM

The trigger pack was just mounted for the test fit. No shims yet, but those are easy to make from plastic or thin brass washers. Good point FM, those shims lesson the thread engagement. When I test fitted on the Prod stub, the threads barely made it to the inside of tube. My search on MC did not find the oem size or one just slightly bigger. It won't be the first sear I had to file. Just can't go back on a Mrod.

I'm not a big fan of the challenger trigger guard. I haven't decided exactly what I'll do yet. Try making one or find another crosman one that might fit. 2 1/2" pipe hanger?

As far as the stock, it is not bad. It is sturdier in the fore grip than the Mrod syn stock. The mrod you can twist back and forth, but it is also floated to the air tube. This, the air tube snaps into. Found the secret to remove the butt plate (remove sling stud). It is hollow as I thought. It will need some form of cheek riser for the higher breech, and I like to stuff/pack with Styrofoam peanuts, to lesson that hollow sound. I believe it will be balanced, but if muzzle heavy there is room for counter weight.

Maybe try this?... it's a conventional looking nitro piston 1 guard

FuzzyGrub · « **Reply #62 on:** March 03, 2017, 08:39:34 AM »

I have one from a vantage, but thought I tried it way back when, and it wasn't long enough. Not sure, so worth finding and trying again. Thx for the reminder.

FuzzyGrub · « **Reply #63 on:** March 03, 2017, 03:43:58 PM »

WARNING! This thread shows modifications done to the air tube. These modifications may have extreme safety consequences. No analysis or testing has been done to verify any safety margins. Any modifications done are at the risk of those performing them.

Made a template from a plastic gal water bottle. The translucent help with locating the holes. Top 3 are reference and then the breech screws.

Then transfer to the max tube:

Also marked for the 3rd valve screw, larger disco screw, and the trigger screw::

Breech results:

Valve screw results. 3rd trigger screw drilled and tapped to 8-32:

FuzzyGrub · « **Reply #64 on:** March 03, 2017, 03:48:02 PM »

Valve Mods:

Exhaust opened from 0.110" to 0.125"

Pocket opened from 0.200" to 0.225"

Slight Inlet increase

Drilled cap to fit the conical spring

Filed flat relief for 3rd trigger screw

Filed flat for larger 3rd valve screw

Rob M · « **Reply #65 on:** March 03, 2017, 05:34:10 PM »

lookin awesome!!!!!!!!!!!!

FuzzyGrub · « **Reply #66 on:** March 03, 2017, 06:45:18 PM »

Air tube pressurized for the over night leak test.

Tater · « **Reply #67 on:** March 03, 2017, 06:55:25 PM »

Looking good John.

Rob M · « **Reply #68 on:** March 03, 2017, 09:41:23 PM »

looks like a very delicate balance with those longer screws for the breech going through the valve..

FuzzyGrub · « **Reply #69 on:** March 03, 2017, 10:02:27 PM »

I couldn't hold out. Shot a string of JSB's. A couple things need to be tweaked, of course, trigger, etc I put in request for a 24" shroud and LW hammer. Also placed order for Huma reg. I will open valve up some more since going reg. (0.140- 0.160")

FuzzyGrub · « **Reply #70 on:** March 03, 2017, 10:07:15 PM »

Quote from: Rob M on March 03, 2017, 09:41:23 PM

looks like a very delicate balance with those longer screws for the breech going through the valve..

Not sure what you mean, they are just the standard 4-40 x 1.125" SHCS. I just ran them in to make sure they were not contacting the edges of the air tube holes.

Rob M · « **Reply #71 on:** March 03, 2017, 10:50:05 PM »

i simply meant the risk of leaking.. since i wasnt sure if the rear of the valve is sealed to the tube... but think i see now the front 2 are sealed off from any air

FuzzyGrub · « **Reply #72 on:** March 03, 2017, 10:54:07 PM »

Quote from: Rob M on March 03, 2017, 10:50:05 PM

i simply meant the risk of leaking.. since i wasnt sure if the rear of the valve is sealed to the tube... but think i see now the front 2 are sealed off from any air

You are correct. That part is sealed off. The holes run all the way through the valve, and do not enter into valve cavity. The front o-ring and there is an internal o-ring that keeps everything in check.

Rob M · « **Reply #73 on:** March 04, 2017, 12:14:52 AM »

gotcha .. i cannot wait to see a pic of the breech installed

Buldawg76 · « **Reply #74 on:** March 04, 2017, 02:34:28 AM »

Looking real good so far and since you could not wait and shot it some already. Is it worth the effort so far in just the preliminary shots showing an increase in performance.

Its likely to early to get shot counts or accuracy results..

Mike

FuzzyGrub · « **Reply #75 on:** March 04, 2017, 08:40:01 AM »

Here are a couple of pictures. I just pulled a scope off the shelf, and slid a shroud on for the pics.

The spring was not long enough, but still had JSB's 18.1g shooting 750-800fps, with low preload. And remember the barrel length has been reduced down to 20".

Accuracy, with no scope or sights, I never missed the wood stove opening at 10yds.

The reg wil take a couple of weeks to arrive, and my friend David (Rocker1) confirmed a shroud and LW hammer.

So plenty of time to work the nits and stuff.

Rob M · « **Reply #76 on:** March 04, 2017, 10:15:31 AM »

that looks awersome man !

screwwork · « **Reply #77 on:** March 04, 2017, 02:37:43 PM »

Quote from: FuzzyGrub on March 03, 2017, 03:48:02 PM

Valve Mods:

Exhaust opened from 0.110" to 0.125"

Pocket opened from 0.200" to 0.225"

Slight Inlet increase

Drilled cap to fit the conical spring

Filed flat relief for 3rd trigger screw

Filed flat for larger 3rd valve screw

John,

Do you have any photos of the (Drilled cap to fit the conical spring) or even a few measurements would be appreciated.
I picked up some of the TA 2122 century springs and I havent modded the valve to fit them yet.
Thx Randy

FuzzyGrub · « **Reply #78 on:** March 04, 2017, 04:22:07 PM »

Quote from: screwwork on March 04, 2017, 02:37:43 PM

John,
Do you have any photos of the (Drilled cap to fit the conical spring) or even a few measurements would be appreciated.
I picked up some of the TA 2122 century springs and I havent modded the valve to fit them yet.
Thx Randy

Randy, I don't have any pictures of that but when I open it up some more, will take some. Basically, the conical spring I have, the large end did not fit in the cap, and was a little shorter than stock. I just picked a drill that it would fit in, and only drilled about half way down. Hope the verbal helps.

screwwork · « **Reply #79 on:** March 04, 2017, 04:35:29 PM »

Hey John, thanks for the tip on openning up the valve cap.
Verbal is fine, no worries on not having any pic's

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Maximus Prime

Author Topic: Maximus Prime (Read 21109 times))