How to time your diesel engine.

OK so you have an injection pump in your hand, the engine timing is lost and you don’t know where to start. Follow these guide lines and I guarantee your engine will run (providing the pump and engine are any good of course)

For the purpose of this I will assume you cannot see any timing marks on the flywheel so let’s begin. 

Remove rocker cover and number one Injector from engine.

Turn engine in direction of rotation until piston rises on the compression stroke (Inlet valve begins to close)

Using a suitable length of steel rod or long thin screwdriver Insert via the number one injector hole until this rests on top of the piston.

Continue to rotate the engine and observe the point where the rod ceases to rise in the bore, the piston has reached top dead. At this precise point make a small scribe mark on the flywheel or front crank pulley and another but more permanent mark on the cover plate.

Continue to rotate the engine until the rod begins to fall in the bore, at this precise moment make another scribe mark on the pulley in line with the mark you have made on the cover plate.

Now measure the distance between these two reference marks, the midway point represents TOP DEAD CENTRE. Make a good mark here on the pulley as this is you permanent TDC reference mark.

Now align this TDC mark with the reference mark on the cover plate.

We now need to measure the diameter of the flywheel, if easier use the front crank pulley. As an example we will assume we have a crankshaft pulley of let’s say 450mm in diameter. We now multiply by 3.14 this will give us a circumference measurement of 1413mm, now divide this measurement by 360 in this case the final figure is 3.925.

Therefore each degree point on the crank pulley would measure 3.925mm
If the timing value is known i.e. 17° BTDC, multiply this by 3.925 = 66.725. Simply turn the engine backwards 67mm and make another reference mark on the pulley, make this clearly visible because from now on this is your injection pump timing point.

Now prior to installing the pump we need to take up any back lash in the gears so continue to rotate the crank pulley backwards for about quarter of a turn then bring forward till your pump timing point mark is realigned.

That’s all very well you say but I can’t find any information on this engine so where do I go from here. Well here’s a tip I have used this for over forty years and it works!

Most of the early diesel engines used timing marks positioned somewhere in the 10°-20° BTDC region. So by timing at 15°BTDC the engine will start and run. Once run if you have white smoke emitting from the exhaust you will need to advance the Injection timing. If when you rev the engine it sounds harsh you may need to retard the timing slightly. These adjustments can be made by movement on the pumps drive coupling or by rotating the pump on its mount. (Hey I didn’t say this would be easy).

For setting the pump spill timing go to pump timing page.

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Mike | Reply 06.06.2017 18.01

Where exactly is the Pump timing page?

Gerald Mathews | Reply 20.11.2016 22.31

Following weeks of misinformation what a find this site has been. Thanks a million with this information I was able to revive my Dorset engine. Top marks!!

NateZ | Reply 22.05.2014 16.54

The information on your website is an enormous help! The detailed instructions on engine timing were great and will really help gettin my project on the road!

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