Locating dimple on timing gear

[100IH]

Everyone needs to learn a method that is always useful under all circumstances. That means don't rely on the distributor. On a new engine or just after head gasket the dist. has been out and needs to be re-installed in time with the camshaft position so one needs a method that does not rely on the rotor. If the rotor has not been moved, that's OK but often the thin washer underneath dist. cam can get lost leaving the cam able to migrate out of time with eveything else.

[30 Closed Cab PU]

Realize most errors in this post so am editing to prevent possible long strings.


I think I understand what is said below is in cases where there may have been an assembly error and the dimple no longer indicates TDC #1, or a new gear timing mark is incorrectly stamped, an alternate method may have to be used. If all is assembled correctly and parts are correct then no problem. Ideally all you should really have to check is points gap and points timing (at full retard) with the dimple indicating TDC #1.


From what I think I understand, since the distributor is fixed, and only the points plates move, rotor position should be a close indicator for #1 TDC if it is lined up with the #1 position on the dist. body.


So changing the points timing does not affect rotor position, bur rotor position affects points timing. So I do not understand below about points timing affecting rotor position.


Would appreciate comments if my understanding is incorrect.

Originally Posted by 100IH

Everyone needs to learn a method that is always useful under all circumstances. That means don't rely on the distributor. On a new engine or just after head gasket the dist. has been out and needs to be re-installed in time with the camshaft position so one needs a method that does not rely on the rotor. If the rotor has not been moved, that's OK but often the thin washer underneath dist. cam can get lost leaving the cam able to migrate out of time with eveything else.

[alexiskai]

Originally Posted by 30 Closed Cab PU

So changing the points timing does not affect rotor position, bur rotor position affects points timing. So I do not understand below about points timing affecting rotor position.

I think all he's saying is that one needs to be practiced in a method of setting timing that doesn't rely on the rotor position to get you in the ballpark of TDC, because there are many scenarios in which the rotor gets disconnected from the camshaft or loses its precision over time.

[katy]

Originally Posted by 30 Closed Cab PU

Realize most errors in this post so am editing to prevent possible long strings.


I think I understand what is said below is in cases where there may have been an assembly error and the dimple no longer indicates TDC #1, or a new gear timing mark is incorrectly stamped, an alternate method may have to be used. If all is assembled correctly and parts are correct then no problem. Ideally all you should really have to check is points gap and points timing (at full retard) with the dimple indicating TDC #1.


From what I think I understand, since the distributor is fixed, and only the points plates move, rotor position should be a close indicator for #1 TDC if it is lined up with the #1 position on the dist. body.


So changing the points timing does not affect rotor position, bur rotor position affects points timing. So I do not understand below about points timing affecting rotor position.


Would appreciate comments if my understanding is incorrect.

"I know you believe you understand what you think I said,
but, I am not sure you realize that what you heard is not what I meant." Author unknown.

[Purdy Swoft]

Originally Posted by 100IH

Everyone needs to learn a method that is always useful under all circumstances. That means don't rely on the distributor. On a new engine or just after head gasket the dist. has been out and needs to be re-installed in time with the camshaft position so one needs a method that does not rely on the rotor. If the rotor has not been moved, that's OK but often the thin washer underneath dist. cam can get lost leaving the cam able to migrate out of time with eveything else.

If the timing is correct in the first place , the distributor can be removed and replaced without needing to loosen and move the distributor cam as the timing will remain the same . If the distributor cam has been loosened and moved it will be necessary to reset the timing . When the timing pin drops into the dimple on the cam gear , loosen and adjust the distributor cam so that the trailing edge of the rotor tip points at the number one contact in the distributor cap with NO clockwise backlash . Anyone that doesn't understand this doesn't really know how to set the timing . Where the rotor tip points is MOST important . Points gap also matters because the spark happens when the points begin to open . This is one reason it is important to pay attention to the points gap when attempting to set the timing . A person MUST also pay attention to the distributor and where the rotor tip POINTS if they expect the engine to run at all .