I'm going to be purchasing some parts from Crosman and i decided i might as well get a 1077 valve to play with and mod this summer. After looking at the parts diagram on the crosman website it appears that they sell the whole assembly with the part number 1077-c34. Does anyone know if this is the right number or if i can purchase the entire assemply with one number? Matthew you should be knowledgable on this one since you have bought multiple valves before.

Thanks for any help.

yes you can buy the valve assembly. the price should be 14.00 something with tax. make sure you order the valve asembly with tube. i gave up on modding it. its to complex and not sturdy enough to dick around with. i figured it will be easier to design a new valve.

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Matt

http://www.network54.com/Hide/Forum/246966

Well I enlarged the transfer port in my 1077. Also removed the hammer catch.

As was said, this isn't what you'd call a heavy duty unit. But since I don't know how to make another valve (yet) I figured I'd hack this one.

The valve is held together by a retaining ring. Under the retaining ring is an evil spring that will fly off to parts unknown if you don't stop it in time.

The transfer port is tiny. There is not much room to enlarge the hole. The end where the brass tube goes is drilled right on the edge of the o-ring land. Hmm. I used a Dremel tool with a small deburring tool to enlarge the hole AWAY from the o-ring land.

Hot diggity! I thought, but was soon brought down when I realised that the hole on the other end couldn't be cut much larger in this direction. It would cut into where the o-ring goes on the cap end. So I ended up with a transfer port a little larger than 2X the original hole size.

Better than nothing. I am ordering a Chronograph this week and will test this modification to see if it is any faster. It seems more powerful. Using 8.x gram Beeman "Gold" pellets, this 1077 was punching craters in my gravel driveway. I was shooting from under the car port since it was raining.

Yes a better valve is a great idea. But for now this is the best I could do.
Dave

Maybe we can hold a contest for a working prototype valve for the 1077? Cash Reward 1,000.00 rewardfor a working valve that produces 1200fps+ . Thats just a sugestion. Something along the lines of that. Any ideas?

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Forum Owner & Administrator
Matthew J. Fulton

I didn't see any measureable difference between supplying CO2 from the stock location (and through the tiny brass tube) compared to directly into the side of the valve. Drilling out the valve ports will not give the same type of gains as drilling the transfer port on a 2240 valve.
There is less than 10 milliseconds from the hammer strike to the time the pellet leaves the barrel. The only way the valve will maintain barrel pressure is to have a larger volume of gas ready to flow when the valve opens.
There is around 8cc's of space down stream of the valve seat, but only 1cc in the valve chamber. Even after extensive porting and a hot CO2 bottle, the best I could get on a stock volume valve was 615fps on a 10.6gr Kodiak and 660fps on a 7.9gr premier HP.