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Holding pistons at TDC
- Thread starter Chris k
- Start date
I don't recall having that problem. You should put the chain on the cam sprocket with side bearings off and then slip the bearings on with the chain in the right place. Not sure what 5°looks like but the most it could ever be off due to stretching is 1/2 tooth. If the bearings don't want to come off, very light sanding with kitchen scotch-brite pad where they're sticking. Read up on getting camshaft centered properly.
Chain is new, It's been used for about 5 mins running before I stripped motor again due to this timing issue.
5° is about 1/2 a tooth on cam sprocket. I'm close to removing cam sprocket and moving it over that 1/2 a tooth.
5° is about 1/2 a tooth on cam sprocket. I'm close to removing cam sprocket and moving it over that 1/2 a tooth.
1 tooth=20* at the crank. If the crank won't hold position, put the tranny in gear and wrap a rag behind the sprocket for friction. Before you move the sprocket, verify the TDC mark. A quick search will give you the drill for that.
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I thought up a test one time you can do without removing it. Do the timing marks, then ask yourself if the cam was one tooth left or right, would the cam mark be more vertical or less. You can actually put a finger on a chain roller and turn the crank until the next roller arrives, and look and see if it's more vertical. In the unlikely event of a toss-up get a new chain
Which way is the timing off? When viewed from the left side, is the notch on the cam rolled slightly forward (11 o'clock) or to the rear (1 o'clock)? New chains are very tight but are supposed to loosen up quite a bit initially after running for a short time. As the chain loosens and the tensioner pushes the slack out from the rear, that rolls the cam backwards a little bit. If you install the cam so it's off slightly in the forward direction, notch pointing towards 11 o'clock, as the chain stretches, it will slowly work it's way into time. And with the rapid initial stretch that takes place, it may happen quickly.
If you still find timing error after verifying the TDC mark, let us know if the cam timing is advanced or retarded, and what head gasket you installed.
That indicates that cam timing is advanced; not surprising, considering that the OE gasket is .043" thick--one reason among several that I recommend Japanese Vesrah gaskets that are made to OE spec. Also the head may not be fully seated on the dowels, which would advance cam timing. Put spacers on the studs, torque to ~15 ftlbs., install the cam chain tensioner (light pressure is enough), and recheck. And again, verify the TDC mark! In 70-79 units the marks are usually accurate, but it's common to find 2 to 3 degrees of error. Later units have marks on a movable plate, and it's anybody's guess what some twit may have done with it.
