The Cat “B” Model governor:
By PM requests, here’s a quick low down on the B gov. Assuming most have read the write-up on the A gov., I’ll take it from there.
The B pump and governor is the second, and/or last generation of mechanical scroll type pumps. It is still based on the rack controlled barrel and plunger assembly, and servo controlled rack. The parts are much easier to get to and repair, and much more efficient than the “A”, being it has controllable torq by screw and spring.
Here’s a brief synopsis of the build of a B. Remove linkage from the breakover lever on the side of the governor. Remove the AF/C and shut-off solenoid. Remove the return line for access. Now we are ready to split the cases. Remove the 1:00 bolt, the short 2:00 and 3:00 bolt (behind the housing), the three longer 4:00, 5:00 and 6:00 bolts, the 7:00 and 9:30 bolt from the front going into the back, and lastly, the two very long bolts at 10:00 and 11:00. Wiggle the back housing loose and pull back three inches. Put hand over governor spring to in place on the way to the bench. Let the spring and collar assembly fall out on bench, and set aside.
Now remove the front section by pulling the other two ¼” bolts from the back side of the front housing, one long, and one short. Wiggle and pull that too. Set aside with other pieces. Remove the three ¼” bolts and servo assembly by turning the servo so that both collars line up to slide off the rack end. Hold over pan and slide servo pin assembly in and out. If it is smooth, break clean and set aside till assembly. Now remove the weight drive by the four 5/16” 12points, but leave the bolts in the hole, as the hold the pins that hold the weights. Set on bench and inspect the Torrington bearing and races for wear that ride on the weights. If gouges are found, the race and/or assy must be replaced.
To replace the Torrington assembly, pull pin from rear of weight carrier. Pull out tach drive rod assembly. With this removed, check the weights for excessive wear on the ends. If all is well, spray it off and set aside. Now slide the spring collar assembly off the back side of the shaft, leaving only the spring compression assembly and Torrington set. Trick #1. Go to hardware store and buy 1) 4” all metal wood clamp. Chop saw a 3/8” wide by 5/8” groove in the center of the end. This is the tool you will use to collapse the spring set and get at the retaining clip. Install shaft set in vice with spring set facing up, squeeze open tool, install on spring set, slide down shaft to expose the ridiculously small snap ring, use two o-ring picks and pry off clip, slide up and off the shaft then remove the Torrington set. This can (or should) be replaced if worn, but can also just be flipped upside down for a new riding surface. Reassemble trying not to launch the snap ring. Install gov spring base assy to shaft, shaft to weight carrier, and pin (with thick grease to hold in place).
Now, re-install carrier to pump case (cam shaft with very large Torrington and two races), servo to carrier, making sure pivot arm locks to spring collar on tach shaft you just rebuilt, and “short block” is built.
To build front housing, clean well with Hotsy or solvent, clamp in vice with top part of housing two inches in and rack head facing up, and remove very small (7/64?) retaining Allen screw from rack guide with rack screws in them. Wiggle off rack guide, and do not loose low idle buffer spring IF IT HAS ONE. Use 3/16” Allen to remove the rack head assy. Trick #2) Pull out the “nail head” (rack bar), remove housing from vice, clamp “nail head” in vice with at least 1/8” protrusion shaft side facing up, and take cut-off wheel and cut small but full length cuts in entire head, not touching the shaft. Now polish the shaft with ScotchBrite. This will remove the sticking of the throttle by draining the hydraulic’d oil from the head to the stop surface of the holder assembly. Re-assemble front housing in reverse order. This part is done.
Install front housing with new gasket making sure weights are collapsed flat and “nail head” is behind governor spring collar. Trick #3) Take a piece of DOT 1/4” plastic 1.5” long, cut two grooves 3/16” apart for a full length split in plastic, and pop it on the shaft by pushing the spring assembly forward. Now the rack is wide open. Loosen both fuel and torq screws all the way loose. Screw inner screw in til it touches stop bar. Back out ¼ turn and lock it. Now screw in outer screw til it touches the torq spring, then give it ¼ turn in and lock it. Rack is maxed and torq rise is the highest it will go. Now pull out on the end of the servo and watch to make sure all weights are locked behind the Torrington. Ready for next step. Replace any bad seals in the rear housing except the tach shaft seal. If that leaks, remove cover and fill with silicone unless it has mechanical tach drive, in which case replace that seal too and possibly tach shaft if worn too much.
Install push collar, wavy washer, 5P flat washer, other wavy, another 5P washer, and an 8M9141 purple stripe gov spring. While it’s apart, screw out low idle (or Jake screw, whichever is there) one turn to compensate for new settings so you don’t have to do it assembled. Also re-seal hi idle cover and get new AF/C o-rings and grease in place. If stripped, Helicoil. Install assembly facing slightly upwards while holding spring assy in place, slide onto tach shaft assy, position onto guide pins with new gasket, cross tighten to 14psi. Install shut-off first (to push bell crank forward), then hook AF/C under groove in bell crank, pull back to make sure it’s locked in groove, then push back in and tighten to 16psi.
Install wires and lines, use shut-down plate to fire (no bleeding/ instant start-up), button up and off ya go. Hope this answered most of the PM’s I’ve neglected as of late. It’s been rough, but I’m not dead quite yet…