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On 26 Aug 2006 at 21:11, Dave Sanderson wrote: > We have a pump for a flat cam, a flat cam and yet it was too long - > but only by a very small margin. I filed the end of the housing, that > is the section that sticks towards the cam and holds the gear that > interfaces with the cam, by a thou or so and now, voila no leaks. > This is a new 30 mm pump from Shadeck. Has anyone else had this > experience. Is this something that happens with these new Brazilian > pumps? I haven't seen this problem before, but I haven't used any of those pumps. When you look at the history of VW pumps, you realize that they increased the pump capacity by a LOT over the years. The gears started out as 19mm, then 21, and finally 26, IIRC. I've generally gone with aftermarket 25s (with flat cams) or OEM 26s (with the later dished cams) just because I found that those parts fit together well and I knew that the late engines didn't seem to have any of the lubrication problems that the early ones had. In other words, there was clearly a weakness here, and VW solved it in stages ending with the 26mm pump. When I've tried other oversized pumps, I've often found that they would either hit the fan housing or the rear mount crossbar (on late engines.) It seemed clear that most of the oversized pumps were never designed with a type 3 engine in mind. Another consideration is the power required to drive a larger pump. The power is proportional to the flow rate x the pressure. Since the pressure goes up when the flow rate goes up, the power requirement goes up ~(flow rate)^2. If there's really no need for the extra flow, then this is just wasted power that can never get to the wheels. That power must be transmitted thru the same cam gears and the tang on the pump shaft, and the increased forces must be supported by a pump housing that now has a shorter support bore. The fact that you had to shorten that bore (only slightly) indicates that the maker tried to fit as much support in there as they possibly could. So this is another case where bigger is not necessarily better. -- ******************************* Jim Adney, jadney@vwtype3.org Madison, Wisconsin, USA ******************************* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~