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Mystery of the Mysterious Timing Marks
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Author:  Daddiojoe [ Mon Oct 16, 2023 7:25 pm ]
Post subject:  Mystery of the Mysterious Timing Marks
1. When the timing marks are lined up on the cam gear and crank gear the valves on #1 cylinder are not fully closed. Engine was rebuilt at a reputable shop.

2. When the timing mark on the crank pulley is lined up with the tab on the timing cover, it's not the same as the marks on the gears AND the valves on #1 cylinder are not closed. The damper seems to be in one piece.

What should I pay attention to here? I am inclined to go with TDC when both valves are closed.

Thanks for your help,

Joe
Author:  slantzilla [ Mon Oct 16, 2023 8:44 pm ]
Post subject:  Re: Mystery of the Mysterious Timing Marks
Cam is timed to Cylinder #6.
Author:  Daddiojoe [ Mon Oct 16, 2023 9:26 pm ]
Post subject:  Re: Mystery of the Mysterious Timing Marks
Thanks Slantzilla! I had no idea. Any idea why?

Joe
Author:  halfafish [ Tue Oct 17, 2023 6:21 am ]
Post subject:  Re: Mystery of the Mysterious Timing Marks
It does sound like your cam is timed 180 degrees out - something you need to fix. It should be timed to #1 not #6. Ask me how I know! :shock: :shock: :shock:

If it was done at a shop and returning it is in the cards, that's the easy way to fix this. Make them do it right. If you do it yourself first find TDC on #1 using a piston stop. Then check the timing mark on the damper - it should be dead on. If the damper slipped it won't show TDC correctly, so if needed mark the damper with the new TDC location. Then DEGREE IN the cam. Don't just line it up dot-to-dot.
Author:  slantzilla [ Tue Oct 17, 2023 8:13 am ]
Post subject:  Re: Mystery of the Mysterious Timing Marks
Quote:
Thanks Slantzilla! I had no idea. Any idea why?

Joe
I do not know. It seems silly to have to time it on 6, then make sure it's TDC on 1 to put in the distributor.
Author:  volaredon [ Tue Oct 17, 2023 8:42 am ]
Post subject:  Re: Mystery of the Mysterious Timing Marks
Remember the crank has to spin 2x for all 4 cycles to happen. Spin the crank 1 full revolution and it'll be set for #1 instead of #6.
Author:  Daddiojoe [ Tue Oct 17, 2023 9:44 am ]
Post subject:  Re: Mystery of the Mysterious Timing Marks
Thanks, Don.
Author:  Charrlie_S [ Tue Oct 17, 2023 11:26 am ]
Post subject:  Re: Mystery of the Mysterious Timing Marks
When the timing marks on the crank sprocket and cam sprocket are lined up, # 1 piston is in the cam split overlap position, and # 6 is TDC compression (both valves closed). When the crank is in this position, the distributer must be installed/set with the rotor pointing at #6 terminal on the cap.

If you time for # 1 piston at TDC compression, the cam and crank sprocket dots will both be at the top (12 o'clock ) position. And the distributer should be set for #1 terminal on the cap.

PS: The damper timing mark should be at zero with #1 and #6 at TDC. If not, there is a possibility of:
#1, damper has slipped
#2, wrong timing cover/tab/mark
#3, wrong year damper
Author:  Dart270 [ Tue Oct 17, 2023 12:20 pm ]
Post subject:  Re: Mystery of the Mysterious Timing Marks
As Charlie said, all you have to do is use #6 dist/rotor orientation to do the ignition timing, and nothing else has to change. You will still use the timing light on the same timing tab and slot on the damper, once you make this tiny change. I would not bother pulling it or returning it to the shop, but technically I suppose they migh fix it for free. Don't count on that...

Lou
Author:  Charrlie_S [ Tue Oct 17, 2023 12:29 pm ]
Post subject:  Re: Mystery of the Mysterious Timing Marks
I don't see anything wrong. Don't worry about the marks on the timing sprockets. They are correct.
Bring #1 piston up to TDC with both valves closed (compression). Install the distributer with the rotor pointing to #1 on the cap. Start it up.
Author:  Daddiojoe [ Wed Oct 18, 2023 9:24 am ]
Post subject:  Re: Mystery of the Mysterious Timing Marks
Thanks, Charlie and Lou. What you are saying makes sense. I will use #1 TDC for setting timing just to make things easier.

Joe
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