Ford 641 timing

lstewart

New User
I have read/viewed lots of info about getting tractor to TDC. Question is that if you can see the flywheel markings through the window, doesn't that not mean you are at TDC? I was thinking the flywheel rotated once for the engine rotating twice.
 
(quoted from post at 12:00:49 12/04/22) I have read/viewed lots of info about getting tractor to TDC. Question is that if you can see the flywheel markings through the window, doesn't that not mean you are at TDC? I was thinking the flywheel rotated once for the engine rotating twice.

The zero degrees timing mark on the flywheel will line up in the window on TDC of the compression stroke and on the exhaust stroke. Most instructions on setting timing based on TDC is for the the compression stroke.
 
Yes and no TDC come up twice on each cycle of the engine. It does so in compression and also exhaust
 
The flywheel is bolted to the crankshaft and it rotates with the crankshaft.. so it is the same speed or turns as the crankshaft. The cam shaft, however is geared to rotate at half speed of the crankshaft and flywheel. And the distributor is also geared to turn at half speed... SO>>>> the engine will turn over two times.... for the cam shaft and distributor make one turn. The cam only needs to open the intake valve on one turn of the engine and the exhaust valve on the next turn of the engine. And the distributor only needs to fire that plug ONLY on the compression stroke tdc, and not on the exhaust stroke tdc. SO.. that means the mark on the flywheel will come by on the fire stroke and on the exhaust stroke. So on ONE stroke, the compression stroke, the distributor must be pointed at the number one plug wire and on the next turn/stroke, the distributor must be pointed 180 degrees or half a turn away from number one plug wire. So the old problem of,, when the mark comes up, are you on the fire/compression stroke, OR.... are you on the exhaust stroke? So you can time it correctly.. or time the distributor 180 degrees (half a turn) off. So you time it only on the compression stroke. BUT.. then getting the plug wires on correctly and not reversed. (which way does the distributor turn?) But that is next weeks chapter.
 

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