Lonestar JR

In R&R of TB and water pump, I've followed Pirtle's and Wally's detailed instructions. I noted and marked the 0 and 45 marks, as in Wally's fig. #5, before removing the belt at the 45 mark. At the 0 mark, the alignment was only ~ 1/2 a tooth off on both sprockets, but as they say, it ran well at that setting. The rotor pointed in the direction as in the figure and remained there after pump replacement and tensioner rebuild. Plugs had been pulled to eliminate compression in the cylinders. A 1/2 tooth movement in the sprockets was corrected before replacing the belt, assuring no rotation of the cams and all slack in the TB to be at the tensioner, again at the 45 mark. Flywheel lock removed...cranked to 0 TDC and...timing marks now are at 20 past TDC!?*! Rotor on bank #1 even points to 3 o'clock! Felt no undue resistance to cranking other than what felt to be valve spring compression. So, cranked back to 45 mark and the sprockets line back up at the original 45 added mark! Phone calls to 2/3 of the Big 3 varied with the only rec to remove the belt, crank to 0, reset the sprockets to original 0 mark, replace the belt and start over.

Wally,...anybody, where should I go from here? As usual, I appreciate any help

Bruce Sinclair

If you used a puller, hammer or anything other than your hands to remove the vibration damper from the crank, you may have damaged the damper. It is possible to cause the inner hub to separate from the outer ring where the timing marks are resulting in mis alignment of the timing marks in respect to the keyway on the crank. I did it on my car and it drove me nuts trying to get everything lined up correctly. I had to replace the damper to get it right. In turn I found out that the wrong damper had been installed on my car by a previous owner

Lonestar JR

Bruce, Thanks for the input. My damper came off without any problem. Still waiting for any advice.

shaaark89

is your harmonic balancer on backwards?

Lonestar JR

I have read other posts where that appeared to be the problem, but mine is on correctly.

Zandramus

Was you harmonic balancer on incorrectly before you removed it?

shaaark89

i need some clarification here. when you crank to tdc on the damper, which marks on the cams are at 20 past tdc? were the marks made at 45 before tdc made on the rotation where the cam gear notch lines up with the housing marks at tdc? (there are 2 rotations of crank per one rotation of cam so you can be 180 degrees off on the cam gear with the crank at zero on the damper)
any cahnce of getting a picture posted?

Lonestar JR

"Z" Balancer was in the normal position as seen in any of the manual pictures.

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by tom falkenberg:
<strong>i need some clarification here. when you crank to tdc on the damper, which marks on the cams are at 20 past tdc?

The original marks on the cam sprocket

were the marks made at 45 before tdc made on the rotation where the cam gear notch lines up with the housing marks at tdc?

Yes

(there are 2 rotations of crank per one rotation of cam so you can be 180 degrees off on the cam gear with the crank at zero on the damper)
any cahnce of getting a picture posted?

As I stated above, Wally's Fig # 5 is identical to my situation.

Again, thanks for eveyone's efforts.
</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">

Z

Are there two sets of numbers on your damper? I've seen one 928 that had two sets of factory stamped numbers in the damper. Looking at the numbers from the front of the engine, one set of numbers was right side up, and the other set upside down on a different side of the damper.

Remove the #1 spark plug and use a stick or something to check if the piston is at the top of it's compression stroke when the timing mark on the damper shows TDC. That will at least confirm that the damper is on and indicating the crank position correctly.

Lonestar JR

Only one set of numbers on the damper. At the present, the crank is at 45 and I'm a little leary of rotating it until I know I want be fung shuing the valve stems.

Z

With the damper at the 45 degree mark, how may teeth are the notches in the cam sprockets away from the pointers there. In other words, when the engine is at TDC on the compression stroke of the #1 cylinder, the pointers should be pointing to the notches in the cam sprockets. How may cam sprocket teeth are those notches away from the pointers?

Lonestar JR

~3 1/2 teeth before the notch in the cam sprocket.

Thom1

Camshaft Alignment:

Cam alignment note: If the belt slipped, you should start with the crankshaft at 45btdc (45 degrees Before Top Dead Center) rather than tdc to keep pistons from hitting valves. Rotors point left and down. Align cam gears with notch on back timing belt cover at 22.5 degrees (3 TEETH) before the tdc notch on the cam gear to correspond to the 45 btdc crankshaft setting. There are 48 teeth on the cam gear, and 24 teeth on the crank gear. Therefore, 2 to 1, and 45 to 22.5 ratio. 22.5/360 = .0625 = 3/48. Therefore, 3 Teeth. Adjust the math if the number of teeth on your cam gear and/or crank gear are different.
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Z

</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Lonestar JR:
<strong>~3 1/2 teeth before the notch in the cam sprocket.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">If the crank is at 45 degrees BTDC, and both sprockets are about 3 1/2 teeth before the pointers point to the notches in the cam sprockets, as Thom's post says, you're where you should be. If the belt is tensioned, I'd slowly turn the engine by hand to TDC and the sprocket notches and pointers should line up. Don't really be concerned if they're off by a little bit (maybe half a tooth).

Thom1

If you corrected alignment by “A 1/2 tooth movement in the sprockets/toothed cam gears was corrected before replacing the belt” adjusting the timing/loosening the cam gear(s), you have to pull the cam covers and readjust the timing. Devek will rent a vcr tape with factory training specifications. Harbor Freight has an inexpensive dial indicator.

Notches in the valleys of the sprocket teeth align with the marks on the timing belt upper rear cover. It is 3 teeth.
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