Monday, 27 May 2019

Timing is all.

   Time came for the MOT but Degsy had caught a cold. It would just about start then run very roughly and would not idle. Humm. Obviously a timing issue. Setting the timing is about arranging the spark to occur that the right moment in the right cylinder. The items that have to be in order are: Spark plugs x 4, points, condenser, HT leads, distributor cap and rotor arm. Setting of the timing is all done statically.

   I have found to make this job much easier it is best to remove the air filter canister. I removed the distributor cap and spark plugs. The contact posts of the distributor looked a bit burned as did the rotor arm I used emery cloth to clean them up. The faces of the points were a bit burned but that is normal so the faces got a tickle up with a file. The plug gaos were a little wide and all sooty which is not surprising given the engine was barely running. The plugs got  a clean with a brass wire brush and gaps reset.

   In order to set the timing the piston in cylinder number 1 has to be position just before top dead centre (TDC). There are a set of marks on the flywheel which indicate TBC, 3 & 6 degrees before top dead centre. Because the engine is spinning the spark has to occur before TDC to give time for the fuel/air mixture to ignite. The resulting explosion occurs just after TDC driving the piston down the cylinder. This timing of the spark occurs in each of the four cylinders in turn. You need only set the timing on cylinder 1 which sets the timing for the other cylinders. Get the timing right and the engine gives maximum power and fuel efficiency.

   Positioning the marks on the flywheel is a pain on my version of series III Land Rover. With the spark plugs removed the engine can be turned over using the cranking handle. First you fit the starting handle to the front of the engine and turn it until the rotor arm indicator cylinder 1 is approaching TDC. The faff is that you have to walk round to side of the engine to view the timing mark through a little port hole at the back of the engine. You have to go back and forth gently turning the handle until the timing marks align. Go to far and you have to spin the engine over again to start the process over. There is no reversing crank handle.

   So with all the ignition items cleaned and set I turned the key to start Degsy. No joy, it was perhaps, worse than before. I removed the spark plugs again to find plugs in cylinder 1 and 3 were oily. That shows they were not firing. Better make a list. I decided the sparks plugs were in good order however I would new to replace points, condenser, distributor cap, rotor arm and I would do the HT leads whilst I was at it.

    £63.00 lighter I had the necessary parts. The plugs were still out of the engine since the previous session the day before. The timing marks were aligned. The old points, condenser, HT leads, distributor cap and rotor arm were now in the bin. The cleaned and reset spark plugs were reinstalled. The contact point set were carefully installed. It is a bit of a stretch to reach the distributor and there are small and vital screws to manipulate that are easy to loose into the engine. The condenser was fitted into its brackets and connected the points. The lead from the points to the Ignition coil was fitted. So far so good. Using a set of feeler gauges the gap in the points is set. It is a fiddly job but perhaps the most important part of the job. Points set, screws tightened, points rechecked and readjusted the rotor arm could be pushed into place.


     Next the distributor cap was put in position, it can only go on one way, and the clips fitted to secure it in place. The last job was to fit the new HT (high tension) leads. The leads carry the spark from the distributor to the spark plugs. They have to be fitted from the correct post on the distributor to the correct spark plug. The engine won't work or will run badly.


 
So with a a deep breath I turned the ignition key...................... the engine leapt into life and once the fuel from the failed attempts at starting had burned off Degsy settled down in to quiet Series III purr. Result.      

Victory for the bloke with spanners! Now for the MOT.

Quick information 
Plug gaps 0.8mm
Points gap 0.36mm
Firing order 1, 3, 4, 2

Tools required
Flat head screwdriver, set of feeler gauges, brass wire brush, spark plug socket, extension and ratchet.