Kit 19 - Valve GearModelWorks 4 inch Scale Burrell
Agricultural Traction Engine Friday: I received the kit at 9 am this morning. It is a strange day as today is my first day of semi retirement. It does have its advantages - no more trekking to the parcel depot - time to catch up on the Burrell - but no job! I might have to start a web page on the crank shaft saga, after a wobbly by the 4 axis mill has caused further delays. If it behaves itself we will be getting a special delivery next week. The kit order is changing again - the next kit will be kit 20, Reverser and Regulator. Thus the kit order is now 1, 2, ... 11, 15, 24, 18, 13, 12, 16, 14, 19, 20, 17, 21, 22, 23
The weightshaft bush is intentionally a sloppy fit into the weightshaft bracket and fixed with Araldite. I am now waiting for the Araldite to go off. I took my time fitting the die block to the expansion link as I regret rushing this on my POP - slop in the valve gear is bad news. I used a combination of draw filling and scraping.  Monday
9th May: Having completed fitting the crank I had time to fit the eccentric
rod ends. There was a slight misalignment at the die block for which
the instructions call for bending the eccentric rod ends. As I was
getting tired and this has to be done carefully I called it a day until tomorrow.
Tuesday: I press on an completed assembly of the valve gear. While everything is stiff I don't have any particular tight spots. I have now removed the valve gear and crank so that I can paint the appropriate bits bright red.  Wednesday:
Masking up the eccentrics and crank was time consuming, it taking all
morning to complete. As appears to be the practice, I will be
painting the sides of the  eccentrics but I am worried that adjacent eccentrics
will rub - time will tell.
I used my air brush to give them a coat of red paint.
I have be agonising whether to fit the pipes under the crank. I
suspect they will need "adjustment" when the mating parts arrive,
requiring the crank to be removed. In the end I decided to fit them
as I will be no worse off even if this occurs. I had to put 20 thou of packing under the right hand bearing to bring
its top level with the top of the housing. Before I did this I could
wiggle the crank and RH bearing up and down in the housing.
The large oiler supplied with kit 19 is for the big end unfortunately the cup has been taped with the wrong thread. The correct tread is 1/4 x 40 tpi, simple to fix if you have a set of model engineer taps otherwise it would have been necessary to return it to Modelworks. Thursday: I decided to investigate why the engine has become so stiff. Prior to fitting the valve gear I could turn the engine over relatively easily and smoothly. I could even turn the engine over by gripping the splined shaft rather than needing the extra leverage provided by the flywheel.
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Tuesday 23rd: Back to the Burrell after a
holiday in the
Lake District and
the 
I
painted the fire doors with high heat gloss before my holiday and this had
set nice and hard enabling me to finally fit them. Looking at this
picture I need to spot some paint of the washers. 
With
the crank moved leftward there was not much room left for all the
eccentrics. To give me some "shuffle room" I chamfered
the bore of the reverse eccentric so that it would slide closer to the
fillet on the crank.
Assembly
of the motion was relatively straight forward. I did fid the eccentric
straps rather tight on the eccentrics. On fully tightening I found I
could no longer turn things. To alleviate this I introduced a shim
between each half of the eccentric strap. I will probably be able to
remove this when things have bedded in.
I
had though it was caused by the stiffness of one of the eccentrics but my
attention was drawn to the main valve rod by a rasping noise. I
striped down this area and discovered that it was very difficult to move
the main valve rod(BU41914). I had previously been concerned at the
surface finish of the main valve rod and decided it was time to improve this. Using successively finer grades of wet and dry paper I imparted
a near mirror finish. I then gave the valve rod a careful clean to
remove all trace of emery particles as I don't want these embedding in the
bearings. My micrometer only showed a shaft reduction of 0.2
thou but on refitting it slid freely.
I thought this was a
good time to roughly set the valve gear so that with luck it won't need to
be completely removed for further adjustment. In full forward gear (ie
where gravity lets it drop) I adjusted the position of the main valve
rod (BU41914) and the valve rod (BU41127) so that I achieved symmetrical
valve opening. I then fine tuned the setting by reference to
admission and cutoff points. The combination of the left & right
hand threads on the valve rod made this very easy. Admission appears
to be at top dead centre with cutoff around 45 deg before TDC. I was
impressed by the lack of slop and the timing symmetry between forward and
return strokes. This is infinitely better than my POP.
