Fixing Classic valve alignment

[Spider-TW]

So I've had a classic pneumag for about 18 months and have been tweaking the on/off pin, orings, on/off valve ports, trigger stops, sear stops, basically everything 'the electrician' ever offered up. It has pretty much eliminated some long range shoot down (that and loosening up the level 10) when I would start to work it hard. I am interested in getting the cycle rate up as high as possible, since my fingers aren't electronic and I can't guarantee a perfect recharge time if the valve is running at an equivalent of 15 bps.

I was thinking that the only thing I had left to even try was porting the reg passages, but that got me thinking about the valve/reg alignment. It's been said on AO that somewhere along the line, AGD started indexing the reg and valve to make sure the holes lined up and this eliminated a lot of shoot down problems and rendered the 'eight hole mod' useless. I figure if that alignment made a noticeable difference and 'the electrician' was adding about 0.012 inches to the bore of that passage (for 2 more bps), I wasn't going to let the valve alignment slide anymore.

Since I don't have an electronic frame I won't have a good test base, but for everyone that hates that little misalignment in their classic valve, here's what I did. I bought a very used mag for my pneu project and the rail groove was wide and the roll pin was tapered, and at worst the valve looked like this;

http://i237.photobucket.com/albums/ff138/Spider-TW/S5000235.jpg

That's a lot of blockage for what should be a straight shot between the gas supply and the reg. So, after cleaning, I filled the groove with JB weld thinking I was going to dremel it back to fit. The first blob wasn't enough to completely fill the gap and I applied some more. After a few hours the JB weld was still soft but not tacky. I put the valve in with the halves matched up and it left a perfect dent. I pulled the valve back out to let the epoxy finish hardening. Now the valve cannot move past perfect alignment and I didn't have to trial and error the fit.

Here's the ugly rail.

http://i237.photobucket.com/albums/ff138/Spider-TW/S5000237.jpg

[matteusz]

nice job on the alignment but for the effort I would prefer to get an old aluminum 8 hole mod back half and forget about it. Then alignment doesn't matter. :D

[Spider-TW]

nice job on the alignment but for the effort I would prefer to get an old aluminum 8 hole mod back half and forget about it. Then alignment doesn't matter. :D
Well, if none of the eight holes match up to the valve body, you will get all of the dynamic flow losses you have with one hole. Your odds are just a lot better at getting at least a partial match with eight holes though.

1) I'm just trying to keep the shortest path to the reg piston straight and clean.
2) My pretty, stainless valve looks perfect all the time now. :D

[athomas]

If you are trying to get better air flow, mark the front halve of the valve on the outside, where the air hole is. Then with the valve put together and on the rail, mark the back half where it lines up with the front mark. Check the existing hole. It might be as simple as opening the hole up a bit in the back section in the direction of the mark.

My original automag valve had holes that didn't even line up. I had to drill a new hole. Its not hard and it makes much better air flow.

If the original air hole is in the correct place but is offset by the z pin alignment, you probably won't gain a whole lot. The overlapping hole size, if it is close at all, is pretty big when compared to the area around the on-off pin that the air passes through.

[punkncat]

Just my .02...

Since I think we can all agree that there is no way that you are actually pulling anything near the actual physical (BPS) limit of the valve in terms of flow and recharge rate, my thoughts are that the shootdown you are experiencing are actually due to short stroking. That is much easier to do, especially when trying to pull fast on the trigger.

In order to fully test this idea, I would think that you need to find a 20bps hyperframe, or spydermag frame, etc. so that you can eliminate short stroking as a possibility. I think you will be pleasantly suprized at how fast that valve will go, even with the holes off a little bit.

Beyond that I think it is pretty cool that you have such an intrest in tweaking that classic and squeezing it like a lemon to get ALL the juice out.
:clap:

[Spider-TW]

I think you guys see right where I'm at.

Yes, I'm scraping the inside of the lemon, just to see how many margaritas I can make. (non-traditional margaritas)

This valve is a 'Classic' and I checked the alignment first. When my eyeball spotting didn't match up to the etching exactly, I rechecked it and I was off. I decided two things; 1) I was going to trust the AGD machinists on the alignment. 2) if I am going to drill my valve out, I'm going to make sure it lines up now and later.

I'm sure all of my drops and chuffs are my own, not so much from short stroking the pneumatics, but from my fingers 'galloping' instead of walking. All I can say is that I've 'got no rhythm, man'. I've noticed that the faster I make the valve, the more forgiving it is and I get fewer and fewer drops and chuffs.

The electrician was saying that he went from 16 bps to 18 bps on an e-frame by drilling the reg passage out from 0.104 to 0.116 inches (iirc). So, I figured if 0.012 inches in diameter makes a difference, a 0.0625 obstruction/turn should make a difference. I guess I could break out the piping calculations. :(

I did drill out the on/off top, .163 on top, .125 on the sides. That really did help. Which reminds me, in case anyone had a doubt, I am using HPA. I'm not sure drilling would be good for CO2.

I figure it is a little like oversampling in audio. As the valve recharge rate and overall reset time goes down, I gain margin or oversampling of my trigger pulls. The more oversampling I get, the less likely it is that I will pull the trigger on a partially charged valve. With an x-valve I would probably have very few chuffs, but I haven't even tried that since the game I'm playing is to see what I can do mechanically with the stainless. :)

[athomas]

You are correct. If you can increase the rate of recharge, then you reduce the amount of time that the trigger needs to be fully forward before the next pull, thus reducing the chance of short stroking.