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Posted By : Stephen Coates, 07-Sep-2006,
06:31pm
Hi, I am in the process of setting up the ignition timing on my 1964 Herald 1200 estate. I was reading the manual and everything was going fine until I
read the following - rotate the distributor body clockwise until the leading edge of the rocker arm just contacts its cam and the points just begin to
separate. The piece that confused me was "the leading edge of the rocker arm", which part are they talking about, because the diagram shows no reference of
this. What is the procedure after overcoming the aforementioned problem. Many Thanks Steve.
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Posted By : Chris Taylor, 07-Sep-2006,
09:37pm
Assuming you have the "proper" Lucas 25D4 (or earlier DM2) distributor, the process is just as described in the manual. Start off by setting the points
gap to 0.015" AT THE OUTSET. Make sure the engine is at top dead centre by means of the pulley mark aligning with the pointer on the timing case. If
you have taken the distributor out, this must be number 1 cylinder (nearest the radiator) firing, at which point the inlet valve for number 4 cylinder
is just opening and the exhaust valve for no 4 is just closing.
If you have not actually removed the dsitributor it doesn't matter whether it is no 1 or no 4 which is at TDC, but you should turn the engine in its
normal direction of rotation to reach the timing mark alignment.
Then turn the vernier screw adjustment on the distributor until all the engraved marks disappear inside the dizzy body. Now loosen the clamp on the
distributor body and turn it a little anticlockwise so the points are well and truly closed and the heel of the points is on the "low" point of the
cam. Then rotate the distributor body CLOCKWISE until the points just start to open. If you are not sure about this point, you can connect a twelve
volt bulb to the coil 12 volt contacts and turn the ignition on. With the points closed, the bulb will light. When they open, the bulb will go out. (A
multimeter will show the same thing).
This now means that the points are just opening with the engine at TDC, so the engine would fire AT TDC. Tighten the clamp on the dizzy at this point.
Now to provide the advance stipulated, you turn the vernier adjustment the opposite way to before, and reveal the relevant number of engraved divisions
for your engine. (Should be something like 3 and 3/4 full divisions for a 1200). That should set your static timing somewhere about right for starters.
It can then be fine tuned by advancing the ignition further (turning the vernier adjustment to reveal MORE engraved divisions) until the engine JUST
pinks when pulling hard at 30mph in top gear , with a fully warm engine.
Note that some manuals (like Haynes) say you turn the distributor body anticlockwise in the above exercise. I think that is wrong. IF IN ANY DOUBT, FOR
THE ABOVE SETTING UP, YOU MUST TURN THE DISTRIBUTOR BODY IN THE OPPOSITE (yes, opposite!) DIRECTION TO THE NORMAL ROTATION OF THE ROTOR ARM WHEN THE
ENGINE IS RUNNING. If you take the distributor cap off and turn the engine over on the starter motor you will see which way the rotor arm turns (and
this is usually marked on both a Lucas rotor arm and the distributor body) and also which way the engine turns so you know which way to turn the engine
(by means of a big spanner on the pulley nut or pulling on the fanbelt) to bring the engine to the TDC position. (Taking the spark plugs out helps to
turn the engine over by hand!)