Can someone measure the stock valve spring in the MR2 AKA SynRod?

[RayK]

I really like the longer, flatter shot strings due to the stiffer valve poppet return spring Crosman installed inside the valve of their revised Marauder rifles (MR2 or SynRod).

If anyone has their valve out or has a spare sitting around, can you please take measurements?

Or if anyone knows if Crosman will sell this new spring, I'll gladly buy some from them.

I want to try one in the valve of my MR1.  These are the specs for the valve springs in my MR1 rifles.

Valve spring 1.442" Free Len X .335" OD X .045" Wire

If not too much trouble, perhaps someone could verify that the stock hammer spring is still the same.  Here are the measurements I took off the stock hammer spring in my MR1.

Hammer spring 2.5" Free Len X .48" OD X .38" ID X .049" Wire

Thanks!

Ray

[FuzzyGrub]

Ray,

I don't have an answer for you, but plan the same for my 25 cal Mrod1/MDRL and for the same reason. 

[RayK]

Yes, 25 M-rod is the gun for this mod.

We have other ways to get long flat shot strings in the smaller calibers, but not the 25.

Did you see the MR2 JSB King string from 870 to 885 for 16 shots with 15 FPS ES?  I've never been able to get less than 19 FPS ES in that range with MR1.  That tune should easily get 24 shots within 3% ES at 43 FPE peak.

To get 24 3% ES shots in my current 25 M-rods, I need to drop peak velocity down to around 830 FPS.

If you find a way to order the new version valve springs from Crosman, please let me know.

Ray

[FuzzyGrub]

Ray,

My guesses on part numbers:

- 1764-034, if they kept the same valve spring across all three calibers.

- 2564-034, if they have a unique spring for 25 cal. 

Try the second, and if they say "not found", try the 1st. 

[cooter472]

This blows my mind, I suggested this a couple wks ago and nobody commented. Every one wants to play with hammer stroke and spring weights, I just randomly was thinking in my race engines we use certain valve springs to control the timing of the valve. Guess I was on to something after all  

[RayK]

Your intuition was right.   

Several of the regulars have known about benefits of a stiffer valve poppet return spring, but it is not easy to find the right one.  I have not found one on my usual spring supply shops like MSCdirect.com or mcmaster.com or CenturySpring.   I'd rather just buy the one Crosman used for the 25 M-rod version 2 valve poppet return which I've seen gives better shot strings.

With the V1 valve return spring, I usually get 1000 psi of usable air for 3% ES shot string, but the stiffer valve spring should allow a wider pressure band - maybe 1500 psi.

More commonly, folks who buy a 25 first get the itch to boost the power way above stock and that usually starts with a stiffer hammer spring - and maybe eliminating the poppet return spring like the A2A valve did.

A stiffer valve return spring should help get a longer flatter shot string within the stock range of about 43 to 45 FPE - possibly one more magazine at your usual tune.

Crosman figured it out and installed a stiffer valve spring in their second version Marauder.

I want to get at least one of the right springs before I can verify this will work in the version 1 Marauders, then I'll try it in my 22 and 177.

Ray

[cooter472]

The last LS engine I built Comp suggested to switch to beehive oval wound springs, gained 5HP and 9ft lbs of torque with the new style springs. And here lately car manufactures are using progressive rate springs so you always have the same ride quality regardless of the load in the vehicle ,kinda duplicating the HPA acting on the poppet. This sounds like it would help benefit the MR1 or MR2. I have a new S-Rod .25 and only shot 2 rds through since my dad past away last month but this bench work thinking is getting me back in the spirit. Ive read on the web where a guy was buying a particular paintball valve spring off of ebay doing something similar.

[cooter472]

there is a member here that does extensive spring testing, not sure of his handle though. read a couple of his post early last yr in the springer section. he is pretty sharp and his knowledge of springs and testing them is excellent

[RayK]

It would be cool to get his input after we get someone to measure their 25 MR2 (SynRod) valve spring.

I'm sorry about the loss of your father.

Ray

[cooter472]

Thank you, I stink at remembering names. When I get some good weather I'm going to do some chrony work in stock trim out of box with some JSB, Predator polys, and some Kodiaks. I'll keep logs of before and after each mod to see what works and doesn't, also I heard on the MROD forum that guys have had positive results from the Bstaley mod on the .25's, just wondering if the return valve spring mod imitates the O'ring mod just in a different way

[RayK]

Bstaley o-rings work great for all Marauders EXCEPT the 25.  This stiffer poppet return spring is not the same as o-rings, but can give more good shots.

Your 25 SynRod should have that stiffer return spring - which is what I'm seeking, but to upgrade my MR1.

Ray

[Motorhead]

Ok guys here ya go ....

2 specs for you, 1st the gen 1 spring specs used in .177/.22 valves.
* O.D. = .333"
* Wire size = .045"
* OAL = 1.425"
* Coil count = 10

2nd spec from a SYNROD .22 valve ( Gold anodized w/raised seat )
* O.D. = .365"
* Wire size = .060"
* OAL = 1.410"
* Coil count = 9

[FuzzyGrub]

Ray,

FWIW:  I plan to purchase a complete Mrod2 valve.  I am not sure if the small poppet and valve changes, might somehow interact with the spring change, to some degree. 


Scott,

Thanks for posting. That is a considerable difference in valve springs.

[RayK]

I plan to purchase a complete Mrod2 valve.  I am not sure if the small poppet and valve changes, might somehow interact with the spring change, to some degree.

That's a great idea.  I will try the stiffer spring in my MR1 valves first since it is not expensive to try.

Can someone describe the other changes made to the valve?  Scott mentioned a "raised seat."

Ray

[Motorhead]

I plan to purchase a complete Mrod2 valve.  I am not sure if the small poppet and valve changes, might somehow interact with the spring change, to some degree.

That's a great idea.  I will try the stiffer spring in my MR1 valves first since it is not expensive to try.

Can someone describe the other changes made to the valve?  Scott mentioned a "raised seat."

Ray

Seat design is like the Gen I .25 valve having seat a raised angled ridge poppet seals against.
* Not impressed so far being 2 of the current valves modified had very ragged sealing edges needing work to smooth out.
Poppets sealing face in both with minimal use where already deeply grooved and FUBARRED beyond using & got replaced.

[RayK]

Thanks Motorhead!