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Originally Posted by Warwitch  Rather than widen the guide rod hole wouldnt it be easier to drill a hole in the front of the handle to vent the air? That way you could keep the tight tolerances. |
Another problem with the tight hole(hey, no laughing) is that when you pull on the hitman lever, the whole assembly torques down. So it still binds on the large hole. This may not be a problem with dual pump rods, but I don't have a back block for it yet, and its a bit too late for me now. Drilling a vent hole would be the best bet for non-hitman style, which doesn't have the torqueing issue.
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Originally Posted by hvacman250 ...In the next few weeks, I am doing a run of single rod hitman mods. I have just bought 2 brand new CCM pump kits to measure. Im sure some of the pump kits I went by had slightly bent guide rods. I dont believe CCM tolerances were off. The 3 pump kits I went by were well used. A slight tweak to the CNC code should make the perfect. |
I wonder if having a 'vortex' shaped hole would help with binding. By vortex, I mean that as you pass through the plate, the radius of the hole decreases then increases. This way when the plate is torqued, the hole that the pump guide runs through 'stays' round. Another suggestion would be to use a less 'bendy' pump arm than stainless steel, if there is such a thing.
One thing that the end user could do to reduce the torquing is to put the pump return spring on the bottom guide rod rather than the top to reduce the 'length' of the lever force.
The pump gets torqued quite a bit.
At rest
Pump being pulled
