RAW Rapid Raw hm1000x modifying the valve

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corny

corny

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Jan 8, 2020
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Elkton, SD
I I have an early HMX that I’m looking to modify the valve for efficiency and power.

The nylon poppet is distorted, I’ve made peek poppets in the past. So I’m planning to go that route.
the question I have, should I make the seat flat? As I’ve heard ppl say it easier to open or should I maintain the angle on the seal?

Secondly, there is a small oring inside the valve, sealing around the valve stem. This oring causes a fair bit of restriction on the valve stem? Would it make sense to remove it?
This would allow air into the hammer cavity during the shot cycle. But it wouldn’t be a lot.

the gun was originally tuned for 21gr nsa slugs at 940fps, at 148bar reg.
I’m hoping to get my get pressure down. I have opened the cavities on the hmx block. By my calculations I have doubled the plenum volume. Going from 18cc to 33cc
Not I would like to address the valve.

IMG_0090.jpeg


IMG_0089.jpeg
 
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Ranchibi said:
I would wait and hopefully Motorhead will chime in and give us some of his wonderful knowledge and/or make an angled poppet and flat and see for yourself what differences they make, I am sure it effects opening and closing somehow for efficiency. I know you will make them work either way!
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Yeah….could make them both ways.

but it would be rather difficult to figure out which is easier to open.
 
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corny said:
Yeah….could make them both ways.

but it would be rather difficult to figure out which is easier to open.
Click to expand...
Maybe by efficiency.....it might be negligible but by shot count, sound....I know that a crisp quick quiet snap is usually a tell sign of an efficient tune and proper valve movement (opening then closing) with my RAW even though RAW's are not really "efficient" with air usage.
 
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Jaxjax said:
K, I found the little bugger...good thing I clicked on this thread as I never new that lil guy was in there, very hard to see in the SS version. I never looked inside the narrow end of my new brass one I just installed a week ago or so.
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So will you remove it? I have read about in different discussions about it being removed, but I’m not sure if they don’t make a new stem with a better fit.
 
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Steel on Steel .. period is seldom a good combo as it is prone to seizure / galling etc ...
In such a case a lined poppet stem bore is a good idea .. BUT, has the probability of the pressure within valves throat during the firing cycle may very well spit the lining material out towards hammer. * ONLY if liner has a shoulder on it and inserted from the throat side can one prevent this from happening.

I prefer a BRASS seat and a poppet head of PEEK. When making these I use Precision drill rod for the poppet stem and REAM the brass seat @ .0015 larger than stem diameter. The blow by is negligible and with some lube applied the wear is non existent.
 
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