Thread: chevy timing

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if i am one toothe off on my timing and i fix it is it right that my timing on the light would stay the same when i go to time the motor again

I have to disagree Denny. If the two gears are one tooth off, yes, the cam timing is changed, either retarded or advanced in relation to the crank. But when that happens, the gear on the cam that drives the distributor is also off, either retarded or advanced in relation to the crank. So the motor will not time with a light at the same place on the damper with it one tooth off and then corrected if the distributor housing remains in the same position throughout the operation.

Now boys!!

OK, if the chain is off one tooth, it has likely slipped at the crank gear, which would mean retarding the cam gear one tooth (effectively moving the cam gear counter-clockwise). If I remember, there are 24 teeth on the crank gear and 48 teeth on the cam gear. If the chain has slipped one tooth at the crank, that would mean the crank has moved clockwise one tooth in relation to the cam gear. Since there are 720 degrees in a cycle, 24 divided into 720 means the crank has slipped 30 crankshaft degrees clockwise. Since the cam moves only half as fast as the crank, that would mean that the cam has been retarded by 15 camshaft degrees. Since the distributor drive gear is an integral part of the camshaft with the same number of teeth as the distributor drive shaft gear, that means that the distributor rotor is retarded by 15 degrees.

So, here's 8ball's question again....
"if i am one toothe off on my timing and i fix it is it right that my timing on the light would stay the same when i go to time the motor again"

If he's timing the motor with one tooth off, then the ignition timing will show, for instance, 15 degrees retarded from TDC. After he fixes the problem and retards the crank gear by 30 degrees, thus advancing the cam gear by 15 degrees, the light will show the plug firing 15 degrees later than it did with the chain slipped one tooth. For instance, in this case, it would show the plug firing at zero or TDC, not at 15 degrees retarded.

If we are speaking in terms of relative rpm's, the cam does not move half as fast as the crank.

I don't know what you mean by relative rpm's, but I do know that in a small block Chevy and any other internal combustion 4-stroke cycle engine you can name, that the camshaft turns 1/2 crankshaft speed.