M59/66 Gas Valve OD to Gas block ID tolerance

[Greatguns]

Anyone have the specs on tolerance between the gas valve OD and gas block ID tolerances on the Yugo M59/66?

[Greasemonkey]

I've never seen a true "specified" clearance. Ancient Yugoslavian mystery..

Easiest thing I would think , is take a sample of 5 to 20 functional rifles, get an overall average i.d. on a working gas block and the o.d. on the gas valve. Then measure a new U.S. made gas valve, and a old sloppy leaking gas valve, this might give you how much it takes to exceed the leakage rate. 

Call it redneck sasquatch ballpark clearance. 

[Loose}{Cannon]

Murray knows....  he has to seeing he makes the oversized SS valve.

[Greasemonkey]

Murray knows....  he has to seeing he makes the oversized SS valve.

Thats the easy way out, measuring adds excitement and anticipation.

What if you gotta undersized bore? What then..

[Greatguns]

Yeah, not into the long road on this, but I do have a message in to Murray on it. Was just throwing it out there for whoever.

Finally got my $50 project out to the range. Had a good group but stovepipes and short cycle. I am pretty sure it is the vavle, but was curious on the specs/tolerance.

[Loose}{Cannon]

Never really measured, but I did flare one out a bit for a tighter fit to the tube.   

[Greatguns]

Never really measured, but I did flare one out a bit for a tighter fit to the tube.   

What did you use, a flaring tool? Did you have to heat it?

Just checked the valve to tube gap. The valve to block is .005" which I thought might be a little loose, but it doesn't feel sloppy loose when installed. The valve to tube however I have just discovered is very sloppy. Thanks for the hint there LC. Now, how did you flare your valve out?? Inquiring minds want to know.

[Loose}{Cannon]

I used a tailstock center from a lathe and pressed the cone into the mouth of the valve in a machining vice.   

[Greatguns]

Hmmmm, That I don't have access to, but I'm thinking maybe a hefty flaring tool might work. Or not, would have to be careful of knurling up the valve with the holder.

I may have to improvise

[Loose}{Cannon]

Hmmmm, That I don't have access to, but I'm thinking maybe a hefty flaring tool might work. Or not, would have to be careful of knurling up the valve with the holder.

I may have to improvise

Just planting the seed.....  you can improvise.   

[Greatguns]

Hmmmm, That I don't have access to, but I'm thinking maybe a hefty flaring tool might work. Or not, would have to be careful of knurling up the valve with the holder.

I may have to improvise

Just planting the seed.....  you can improvise.   

You know me well, haha

[Greatguns]

Got this info from Murray today;

....Our Gas Valves measure right at .590". (Gas Block ID is .591/.592") And they are .010" to .015" longer as well. As long as the holes and slots in the Gas Block are not dented inwards, our Valve will be a very snug, but moveable fit. But with a new Tapco Gas Tube, it might be too long. Is there any forward/rearward movement of the gas tube when it is installed on your gun with the original Gas Valve? If so, installing our Gas Valve "as is" would be best, but if you have a tight fit front to back, then you might request we reduce the length slightly so it fits properly with the new Tapco tube, and the added diameter would likely be all it takes to get it running better.

After discussing it with him I opted to just spend the $21 and get the new one. I was concerned with the .006" gap between my old valve and the block. I remeasured and it came out .585" OD on the valve and .591" ID on the block.

I'll let you all know how it works out.

[Loose}{Cannon]

Good deal

[Power Surge]

Another trick is to wrap a piece of wire around the machined groove in the valve. Some people use a paper clip, I used a piece of .030 stainless safety wire. Works like a piston ring. I did that in mine for free, and it cycles perfect after that.