Lock the crank shaft at No. 1 piston TDC by inserting a 1/4" punch in the hole below the starter. Remove the rubber plug from the hole first. You don't need a special tool. You do not need to lock the camshaft either if you are careful. The mark on the exhaust cam sprocket is sufficient to locate TDC. There is no mark on the inlet side because of VANOS.
Thank you kindly Yaofeng. I'll do the 1/4 punch trick. Also, from your experience, if my harmonic balancer is shown to be on the TDC mark on the block, would there be any reason to insert the 1/4 inch punch? (In other words, can I rely on the harmonic balancer TDC mark and the TDC mark on the block to give me proper alignment without the insertion of the punch?)
I did not see a mark on the exhaust cam however. Would you know where it might be located or what it might look like? The exhaust cam sprocket does have arrows on it that are supposed to be positioned "up". Not sure which way is "up" because if one of the arrows is straight up, the elongated holes do not position with the timing chain sprocket holes as they should (to the left and then centered after I tightened the timing chain dummy insert tightener; they don't even get close to proper position).
Sorry for the questions, I've been having tremendous difficulty getting the proper alignment (right now my timing is way off and I'm afraid if I don't get it right, I'll bend the valves like I did the first time I put the head back on).
Get a Bentley. Also there is a detailed description on the Pelican site on the M50TU engine timing. Google it.
With respect to TDC, the damper is a good way to determine TDC. Actually only at the No. 1 piston TDC will you able to lock the flywheel inserting the 1/4" punch through the hole. Because at No. 1 piston TDC the hole on the flywheel will line up with the hole below the starter.
A number of pictures below. They are at No. 1 piston TDC. Keep in mind there is no mark on the cam sprocket on the intake side of the M50TU engine (because of the variable timing). At No. 1 piston TDC the first cam lobe on each cam faces each other in the 1:30 (exhaust) and 10:30 (inlet) orientation. Use the exhaust sprocket to line up the exhaust cam with the arrow at 12 o'clock. Then use the first exhaust cam lobe orientation as a guide for the inlet cam. You will have to rotate the inlet cam ever so slightly when you fit the VANOS gear up. With Bentley and the Pelican site description you should be able to set TDC.
Correction, I think the last two pictures are slightly off TDC.
Yaofeng - This is great information. I will heed your advice. Just one more question please, if I may? The hole beneath the arrow on the exhaust camshaft sprocket: Would you know the purpose of it? Is it for marking purposes perhaps? Behind it in the picture you posted appears to be a mark on the timing chain sprocket attached to the exhaust cam (perhaps it is the mark you refer to in your first post with reference to the camshaft and TDC?)
I don't know what that hole is for. No bolt is going through it. For TDC indication? You can verify No. 1 piston TDC by inserting a punch through the hole below the starter to lock the flywheel as I mentioned and verify if the hole line up at 12 o'clock.
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