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Old 10-28-2011, 04:49 PM   #1 (permalink)
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Join Date: Dec 2008
Location: Houston, TX

Rainmaker Restoration Project - w/ hammer face pic

I found an older (?) bag o' rainmaker in the BSTs and wanted to see what you guys were talking about. It was in great condition, other than "some assembly required". I did some homework and found some old threads, this one turned out very helpful...

Rainmaker stock board dwell...

Thanks to MondoMor and Mad Marty for that.

These things are a lot bigger after you put them together.
And yes, on HPA and a ported valve, still loud.

The hammer face picture is on the last post.

I wanted to keep it mostly original, but add some Mad Marty mods and see what I could do with the original design

I bored out the valve to match the body ports, recessing the seat since there was plenty of meat, and made a new valve poppet.

I worked up the Mad Marty carrier mods with a link set screw and center post.

I was studying the sear alignment for what I remember is MM's mod #5 for polishing and fitting the sear for easier lock up. What I came up with instead was to fit a 1/16" roll pin in the back of the hammer which holds the sear in alignment with the carrier when they are not yet latched. I'm surprised these things worked originally. Between the tool marks on the carrier face and the way the sear was bumping the vertical edge of the carrier, it looked like it would just ram the parts together all the time.

This roll pin mod also keeps the sear spring tucked up in the hammer so it doesn't drag the body.

Never mind the 1/16" hole near the front of the hammer. I wasn't a good day in the garage.

I'm trying to show where I ground a little off the sear for the final fit, making sure that the sear has a full latch on the carrier. If I had drilled the roll pin hole higher up in the hammer, it would not have been necessary.

I decided to try some high volume (3/32") promaster tubing on the LPR supply to the solenoid. Partly to add volume and also to try to get away from the tiny elbows that were on there. It may kink enough to be the same, but it seems to work well enough.

I ground the ports in the LPR stem, and added some flow slots in the top. Those are just in case the stem gets pushed up against the tubing fitting, which seemed like it would keep the pressure from kicking the piston closed in good time.

Made a new bolt. Mad Marty definitely has a point on custom bolts. The stock bolt didn't seem to fit the space very well. The largest o-ring diameter on the bolt was around 0.685, while the bore was very consistent at 0.699

Bored out the HPA back to add some volume.

I polished and cleaned up the LPR orifice. That is not a shadow in there, it is partial anodizing. The hole had a small burr in it and the seat was uneven, so I cleaned that up. With all the odd mods, it still runs right at 80 psi.

I still need to go through and loctite it all down and will probably stiffen the valve spring since I seem to have a lot of velocity overhead available (I started at about 350 fps).

I think I'm going to work on the feed neck and get a loader matched up to the detent next.


Got my macro line fittings and added a feedneck mod. My tape wasn't thick enough and I made a couple of marks on the body from the lathe chuck, but I got away from the side screw feedneck. There's plenty of meat on the inside of the original feedneck to thread or clamp onto.


A couple of odd notes. The ball detent was bent too deep, not just protruding too far into the breech, but also presenting too steep of an angle to the bolt. My first assumption was that it was intentional, but I'm not so sure. Along the same lines, there were only four pair of spring washers in the HPR, where the original design was five. I bought some extra washers from JT parts as I couldn't find the exact size anywhere else (and the JT price wasn't bad either). Five pairs is not as stiff and should last longer and provide higher flow for the same pressure setting.
My Feedback

some things are stickier than others

Last edited by Spider!; 12-20-2011 at 09:21 PM.
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