Setting Tool for Villiers MK 20/25 Timing.

I was thinking about setting the timing on a MK 25 engine and i remembered from the past that it was possible to have a tool to help with the setting of the timing. So i found a old 18 mm plug the sort you can dismantle for cleaning the centre porcelain was badly cracked so i dismantled the plug and threw it away and filed off the the bottom tab which you use for setting the plug gap,my next job was to make a plug to fit into the top part that was left after we had discarded the porcelain i made a steel plug a nice sliding fit about 1" long with a 1/4" U N F 28 tpi through the centre put on some araldite and placed in the sleeve level with the top once this plug was set we have the makings of our tool i selected a 3" long x 1/4" unf bolt put on a nut and screwed it well up i then screwed into our gauge . You now need to get the piston on T D C on the compression stroke screw in your gauge and screw down the bolt until it touches the piston and secure it with the lock nut,then remove the gauge i then set a depth gauge from bottom of bolt to bottom of our plug gauge and zeroed it i then loosened lock on top and advanced the bolt .1875 which is 3/16ths i then wound the engine back a little way remember it is still on compression stroke you then bring up the piston to touch the bolt and set the flywheel so the points are on the point of opening you will already have set the points gap tighten the flywheel on the shaft and the timing is set double check to see that nothing has moved when you tightened the flywheel if not you are ready to go. You can of course use any thread you like. The best would be 5/16ths" M E (model engineer thread) with this you can advance the bolt in your gauge 6 turns= .1875 thou bang on size, the only draw back is obviously you need M E 32 tpi tap and a die because you will not be able to buy a 3" long bolt , if i make another gauge this is what i shall do. By the way it has taken me longer to post this idea than it took to make the tool.

Nice one Chiefy. We were thinking along the same lines but doing it with the head off (for de-coking) using a piece of bar, threaded to take a bolt to stop the piston and secured in place by the cylinder head bolts. Will try and get around to it sometime and post the result.

Woodsman wrote:Nice one Chiefy. We were thinking along the same lines but doing it with the head off (for de-coking) using a piece of bar, threaded to take a bolt to stop the piston and secured in place by the cylinder head bolts. Will try and get around to it sometime and post the result.

HI Paul, Depending on the engine and the piston crown coming level with barrel top or below you could in someway restrain the crankshaft from turning and dismantle the flywheel work on points etc put flywheel back on in same position you took it off and if you are lucky you are ready to go if not you will be very close and only need fine tuning of timing. If your piston has a crown which is higher than top of barrei eg on some O H V engines you would need spacers to put under your locking bar.
Yes a good idea I like it let me know how you get on,Chiefy .