What is this tool doing?

[Mordan]

Hello,

in my tool-buying spree, I saw this. I asked the seller and he says

"This kit is for setting your magneto ignition timing on your car or motorbike. "

But frankly I still don't understand how it works. How can it help me setting TDC?

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Top Dead Centre Set

This Top Dead Centre Set comes complete with 5 extentions pieces and plug adaptor M14 x 1.25 standard plug fitting.

Can be supplied with a 0 - 1" long reach clock graduations are .001"

Or a 0 - 10mm Metric Clock graduations are 0.01mm
http://i7.ebayimg.com/03/i/001/0a/a0/6000_1.JPG

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thx!

[shogun]

Top dead center is the datum point from which engine timing measurements are made. For example, ignition system timing is normally specified as degrees before top dead center (BTDC) although a very few small and fast-burning engines, require a spark just after top dead center (ATDC), such as the Nissan MA engine with hemispherical combustion chambers, or hydrogen engines.

Top dead center for cylinder one is often marked on the crankshaft pulley, the flywheel or dynamic balancer or both, with adjacent timing marks showing the recommended ignition timing settings as decided during engine development. These timing marks can be used to set the ignition timing either statically by hand or dynamically using a timing light, by rotating the distributor in its seat.

In a multi-cylinder engine, pistons may reach top dead center simultaneously or at different times depending on the engine configuration. For example:

In the V-twin configuration, the two pistons reach TDC at different times, equal to the angular displacement between the cylinders.
In the flat twin configuration, two opposing pistons reach TDC simultaneously, which is also called 0° displacement.
In the straight-4 configuration, the two end pistons (pistons 1 and 4) reach TDC simultaneously, as do the two center pistons (pistons 2 and 3), but these two pairs reach TDC with an angular displacement of 180°. Similar patterns are found in almost all straight engines with even numbers of cylinders, with the two end pistons and two middle pistons moving together (not necessarily 180° out of phase however) and the intermediate pistons moving in pairs in mirror-image around the center of the engine.
In the flatplane V8 and many larger V engines, the piston motion within each bank is similar to that of a straight engine, however in the crossplane V8 and all V10 engines the motion is far more complex.
The concept of top dead center is also extended to pistonless rotary engines, and means the point in the cycle in which the volume of a combustion chamber is smallest. This typically occurs several times per rotor revolution; In the Wankel engine for example it occurs three times for every one revolution of the rotor.

By finding the volume of the cylinder using TDC and BDC and multiplying it by the number of cylinders you have, you will get your engine displacement.

http://en.wikipedia.org/wiki/Top_dead_centre

[Mordan]

Top dead center is the datum point from which engine timing measurements are made. For example, ignition system timing is normally specified as degrees before top dead center (BTDC) although a very few small and fast-burning engines, require a spark just after top dead center (ATDC), such as the Nissan MA engine with hemispherical combustion chambers, or hydrogen engines.

Top dead center for cylinder one is often marked on the crankshaft pulley, the flywheel or dynamic balancer or both, with adjacent timing marks showing the recommended ignition timing settings as decided during engine development. These timing marks can be used to set the ignition timing either statically by hand or dynamically using a timing light, by rotating the distributor in its seat.

In a multi-cylinder engine, pistons may reach top dead center simultaneously or at different times depending on the engine configuration. For example:

In the V-twin configuration, the two pistons reach TDC at different times, equal to the angular displacement between the cylinders.
In the flat twin configuration, two opposing pistons reach TDC simultaneously, which is also called 0° displacement.
In the straight-4 configuration, the two end pistons (pistons 1 and 4) reach TDC simultaneously, as do the two center pistons (pistons 2 and 3), but these two pairs reach TDC with an angular displacement of 180°. Similar patterns are found in almost all straight engines with even numbers of cylinders, with the two end pistons and two middle pistons moving together (not necessarily 180° out of phase however) and the intermediate pistons moving in pairs in mirror-image around the center of the engine.
In the flatplane V8 and many larger V engines, the piston motion within each bank is similar to that of a straight engine, however in the crossplane V8 and all V10 engines the motion is far more complex.
The concept of top dead center is also extended to pistonless rotary engines, and means the point in the cycle in which the volume of a combustion chamber is smallest. This typically occurs several times per rotor revolution; In the Wankel engine for example it occurs three times for every one revolution of the rotor.

By finding the volume of the cylinder using TDC and BDC and multiplying it by the number of cylinders you have, you will get your engine displacement.

http://en.wikipedia.org/wiki/Top_dead_centre

thx for your lengthy reply shogun... should I infer that this tool is useless for BMW enthusiast?

[Jon K]

Yes!

[whiskychaser]

No car that I can think of has magneto ignition-you normally find that on motorbikes or lawn mowers. A much more reliable way of finding TDC is to look at the timing marks:) If you want to see how accurate they -or you- are, put a wooden dowel down no. 1 plug hole and turn the engine over by hand until you find the middle of the point where it poises at the top. If that doesnt correspond with the timing marks there is something wrong :D