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turbogrill

Engine assembly - #1 cyl at TDC how accurate? Important?

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Hi,

 

I am about to put on my head onto the block. (N47 head, flattop pistont, nothing crazy).  According to all the manuals the cam should be aligned to the mark and #1 cylinder should be at TDC.

 

How accurate at TDC does it have to be? I have turned the crank a few times and I think it is at its top location, but I haven't done any accurate measurements.

 

What happens if it's 2-3 degrees off? Will the cam be out of phase by this amount or will it fix it self once I put the chain on?

 

Thanks

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Is the front timing cover off I assume? Then it doesn't matter to be "exact", it just gets you in the ballpark for the marked links on the chain. One mark will go on the crank sprocket and the other on one of the three marks on the cam (which allows for stretch adjustment).

 

Usually once I get the crank side on and the cam sprocket in the chain properly I use a wrench on the block section in the middle of the cam to adjust the cam a degree or two as needed so the sprocket slips on. Then you can put the tensioner on and reassemble the front cover.

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Correct, make sure the piston is visually at the top (it actually pokes OUT just a touch if you look closely, but don't worry if you're not that exact) which make the marks easy enough to align. Make sure the camshaft lobes on the #1 piston are both "up" and you'll be in the ballpark on the head. Then use the lighter color links on the chain to be "sure" timing is right.

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