Last I heard, Compresseurs Quebec were selling parts for Webster, but I don't see them listed there anymore. Those head unloaders on that Model 81 are pretty rare. Websters were a frustrating breed. Some of the older stuff was as tough as they come, but they had some not too good ideas, like clamping the valves in place using the head gaskets between the upper cylinder head plates. The older, brass connecting rod models were very strong units. When they went to the aluminum rods, they tended to knock out the small ends. The HP iron pistons also would wear a lot, inducing a lot of slap between the rod pin and the piston, leading to lots of slop. They also didn't radius the crank journals, and more than one Webster crank snapped at the counterweights. The Model 81 you have was Webster's last unit, and they were trying hard to rectify their self-imposed unreliability (cheaping out on parts and designs). They introduced roller bearings in the small ends and went back to babbitt inserts in the big ends. Unfortunately, it was all over for Webster by the late 80's. A group of employees bought up all the spares and sold Webster parts throughout the 90's, so a Webster was still a good bet for quite awhile after the company folded. I guess they sold the rights to Compresseurs Quebec to sell the spares. The market for Webster parts must be getting pretty small by now, but if you can find the parts, the Model 81 can be a pretty reliable unit.
The unloaders are set up wrong on that pump btw.
I see you are in Ottawa, so am I. Contact Regional Compressor. Luc or Gilles should be able to tell you if you can still get parts.
