After a spell of bad weather, I'm finally back working on the SR-1. Then it took me a while
to get the fuel filter and the solenoids housing detached from the front cover.
That was a good call on unhooking the spring. Once I had the cover off and got access to
the head of the screw, unscrewing it was no problem. Oddly, an ordinary 10-32 nut would run
over the screw just fine. Apparently the bass bushing has much tighter tolerances--I suppose
to prevent oil from leaking out. I cleaned up the the threads on the screw with a die,and now
it turns easily, so it should be easier to remove next time.
Now the bad news: nothing looks obviously wrong. It's difficult to measure the play in the
entire linkage, from weights to rack. But the most play seems to be in the joint where he
rack meets the lever, perhaps around 0.2 mm. I'll try to get a more accurate measurment
tomorrow.
If correct, that means at most 0.2 mm of wear--and probably a lot less, since it can't have fit
perfectly when new. The linkage is kept under tension by the speeder spring and should
never go slack, so shortening due to wear is more of worry than play.
There is no noticable wear on the pivot or lever arc, but a lot of side-to-side travel. However,
it appears to have been designed that way: the pivot shaft is held in place by a C-clip on either
end, each with a flat washer, and that leaves it free to slide about an 1/8" inch. Perhaps that's
to spread out the wear on the lower end, where it meets the governor sleeve.
Also, with the rack set with the calbiration mark to the right of the fuel injector pump (full
mark exposed), and the govenor sleeve flush with the lever end, distance 'M' appears to
be correct (1/2 inch) if I understand the diagram on p. 27 and the text on p. 28 correctly
(of the Lister *Instruction Book for Air-Cooled DIesel Engines* (1970).
The calibration procedure on page 28 calls for a feeler gauge (0.015 / 0.017 inch for the
SR-1).to be inserted between the at point 'G' between the start-stop control lever and the
"run" position control lever stop. With this shim in place, it says to loosen screw 'H'
and turn the control lever locating plate it until the calibration mark on the rack lines up with
the right edge of the fuel pump.
Q1: Am I correct in thinking this is setting the leftmost rack travel, and that this corresponds to
the maximum fuel volume per injection?
Q2: Also, if wear has shortened the governor linkage, shouldn't that increase the maximum leftward
rack travel (and thus maximum acceleration)? The governor weights excert force that moves the
rack to the right, decreasing fuel volume. But the symptom I'm seeing is too little governor feedback,
not too much (oscillation).
Q3: is it possible the governor isn't the problem, but the fuel injector pump or even the fuel
injector? (Both are new as of the rebuild 1 year ago.)
Unfortuantely, this engine is remove-start so it doesn't have a plate with stops--nor is there
any obvious place to insert a shim. Guess I'll have to go by the distance onthe rack, which
Lister kindly provides: 0.046 / 0.052 inch.for the SR-1. (There's a typo: it says "0.46 / 0.052"
but the minimum can't be larger than the maximum. Fortunately, it also gives the same
tolerance in metric: 1.17 / 1.32 mm--which agrees with my correction to the text..)
With clothes pins on the rack, I was able to get a ballpark number of less than 2 mm of travel.
Tomorrow I'll try to get a more accurate measurement. The tolerances on rack movement
appear to be very stringent: 0.052 - 0.046 = 6 thou. The manual warns that the "maximum
must not be exceeded."
I count 5 joints, all steel-on-steel, in the linkage between the governor weights and the rack
(plus one cotter pin). The joint at the top of the lever is a bent rod stuck in a hole in
the lever, with dubious alignment. Even assuming the splash lubrication is adequate, I'm
scratching my head, wondering how it lasted this long. :-)
Q4: How often have folks here had to adjust control lever locating plate on their SR-1 engines?
Once a year? Once a decade?
Sorry to ask so many questions, but I haven't solved the mystery (and may on the wrong track),
so any clues would be much appreciated. Thanks!