Excessive RPM drop under load ?

[Ronmar]

Veggie
  A key spot to look at is where the governor linkage attaches to the sliding fuel rack rod on the Injector Pump.  This is done with a little forked rod yolk affair that plugs into a hole on the top of the upper bellcrank. If the rod that plugs into the top of the bellcrank is not loose enough to slide freely, it can bind and limit your travel out to full throttle.  I had to do quite a bit of work on mine to get this key part to slide to the full throttle position freely.  Unfortunatly this also made it a little sloppy, so the governor response to load changes was not crisp.  IE: the engine RPM would change, the linkage would move, but the slop in the yoke component would absorb the movement and not immediatly move the fuel rack to compensate for the RPM change.  My fix for this was a VERY lightweight spring across the upper bellcrank.  This holds the yoke assembly against the end of it's slop, but still allows it to reach it's full throttle position smoothly.  This was my biggest hinderance to smooth governor/throttle response.  Even before I fixed it, it was still consideralby more responsive to load increases than you describe.

Here is a pic.  Again, the key part is located at the top of the diagonal spring.  It needs to be able to pull the fuel rod/rack out to the left to full throttle, without pulling down on the rack and binding.  IMO, the rod on that yoke assembly, and it's associated pocket in the upper bellcrank are not long enough to perform this task properly.  If I redesign it, I will probably shift the whole upper linkage to a weedeater throttle cable...

[listeroil]

It is possible to achieve quite good RPM regulation on a Lister 8/1 but it takes a bit of work to get it right.
To get the RPM correct you need a revcounter or a HZ meter and a load to put on the generator. I use two 1.5kw electric electric fires and a 1.5kw hot air gun on my 4.5kw Startomatic.
First of all start your set on low load then check what revs your engine is running at 850 for an 8/1 or 650 for the 6/1 or you can use a HZ meter and use 50HZ or 60HZ to set the revs correct. Then put maximum load on the generator and check the revs again it will probably drop. If the revs drop stop the engine and slightly lengthen or shorten the adjustable rod from the governor arm to the pump quadrant. Start the engine again check and adjust low load rev (50HZ or 60HZ) and then fully load up the generator again. It should have made an improvement to the revs. Keep on adjusting and reseting the rod and governor spring and it should be possible to get good revs regulation from min to max load. This takes quite a bit of time but it starts to make sense when you do it. Once you start adjusting the rod it gets better or worse and then you know which way to adjust it.
Mick

[dubbleUJay]

Thanks Listeroil,
I think this is probably one of the 1st things to adjust before looking at anything else.



and for the following pics/answers bellow, I thought no one knew as I asked the question so long ago! Sometimes I can kick myself, I should have thought to look in the manual at the parts list!

[listeroil]

WJ

I have checked the lister manuals and the lister 3/1 and 6/1 have the same governor weights according to the part numbers.
The 8/1 weights are a bit lighter. Heres some pics.

Mick



                                                       8/1




                                                       6/1

[quinnf]

The geometry of the bellcrank to IP rack is rather primitive.  No, I'm being kind.  It's really primitive.  A toothed quadrant and a rack would have been a better way to translate rotary to linear motion.  

First thing to do is to remove any paint from the shaft of the fork that goes in the hole in the top of the bellcrank.   As Ron mentioned, as the bellcrank rotates, that fork has to slide in and out of the hole in the bellcrank without wobbling, or binding, so the stubby little shaft on the fork has to be free.  I had to run a drill bit through mine to get rid of the burrs left over from manufacturing.  Then I polished it using carborundum compound.  Once the fork slid in and out of the bellcrank freely, I had no problem.  Set the speed unloaded to 62 rpm, and when gray smoke starts to appear, you're down to about 58 rpm.  That's not bad, considering the vintage of the design, and the crudeness of the final (Indian) product.  

You notice that there is no paint on Mick's (Listeroil) linkage.  That's probably the best way to keep it.

Quinn

[BruceM]

"shaft of the fork that goes in the hole in the top of the bellcrank"

Same piece on my 6/1 was so poorly made that it bound up badly.  I drilled out the hole, put in a bronze bushing that gave better support, polished the yoke pin.
It helped a great deal. 

The sliding yoke is a bad design, as Quin suggests, the mechanical governor it would perform better with a better linkage.