timing belt help

[nomadclimbing]

Im trying to put on the timing belt on my 83 944 na. The problem Im having is when I pull the belt tight to loop over the camshaft gear from the crankshaft it doesn't quite match up on the teeth. i was wondering if either gear could be slightly turned to pick up the slack? Maybe a half a tooth and which gear would be better to move and which way? I have read all the procedures from Clark's garage other forums and I am using the Porsche shop manuals also.

[many944s]

First.... I would assume you have a flywheel lock in place
Or not.

Either way, you can move the cam shaft pulley a little to get things lined up. Then when everything is together, and you turn the engine over BY HAND to check the timing and tension you can see if the TDC and Cam marks line up properly. Turning the cam a tooth or tooth and a half is not going to cause any collisions.

Post back if you need more help!

-Nick

[troyer]

This is a bit confusing to me too, especially after reading this FAQ (8.4):

http://www.connact.com/~kgross/FAQ/944faq08.html

It says, "Be sure to set the engine to TDC -10 degrees."

Anybody know why you would do this? When I set my timing, I made sure I could see the notch on the back of the flywheel through the window by the starter (the mark on the front was not visible, I turned the crank slowly a few times looking for it).

I had removed the cam tower previously, but after I put it back on, I made sure the alignment mark on the cam was aligned with the mark on the distributer housing.

Is there a reason to then turn it -10 degrees? Also, the site mentions that the notch on the flywheel should be pointed directly down, but the window is not directly on the bottom. Did I do this right?

[mikepellegrini]

I'm not sure why you would want to be 10 deg BTDC.

Here are the links to the pertinent parts of the GSM at Clarks:

http://www.clarks-garage.com/shop-manual/eng-06.htm

http://www.clarks-garage.com/shop-manual/eng-10.htm

You want to be at TDC on the crank and on the camshaft. I've followed those directions and haven't had any problems yet.

[aj951]

I think that is a mistake in the last part of 8.4 in the FAQ regarding TDC-10 deg when removing the belts. I keep the timing marks aligned when I remove and replace the belts. I do however set it to TDC-10 deg (1.5 teeth on the cam gear) when adjusting the timing belt tension.

A.J.

[mikepellegrini]

Originally Posted by aj951

I think that is a mistake in the last part of 8.4 in the FAQ regarding TDC-10 deg when removing the belts. I keep the timing marks aligned when I remove and replace the belts. I do however set it to TDC-10 deg (1.5 teeth on the cam gear) when adjusting the timing belt tension.

A.J.

I think the purpose of that is to redistribute the slack - AFTER you have the new belt in place, but before you measure the tension.

[aj951]

I agree with redistributing the slack after the new belt is on but that is not what is written in the last paragraph of 8.4. Here is a quote from the last paragraph of 8.4.

"I also recommend getting a good manual (Chilton's or the factory manuals) to assist in this process. Be sure to set the engine to TDC -10 degrees (as outlined above) before removing the belts. In addition to the two reference points mentioned above, there are also alignment marks on both of the balance shaft sprockets. Make sure that everything is aligned before removal. Once this is done, R&R the belts (or go further & replace the tensioners/rollers if you are doing so at this time). When replacing the belts, make sure that you keep the reference marks aligned! Being off on the camshaft sprocket will result in valve damage; being off on the balance shaft sprockets will result in much vibration from the engine."

Too me, the second and fourth sentences contradict themselves. The second sentence says TDC-10 before you remove the belts while the fourth sentence says to align everything before you remove the belts.

Confusing to me but I am easily confused.

A.J.

[HondaDustR]

The -10deg is for tensioning after belt installation. Oftentimes the belt will not fit exactly with both marks dead on, especially with a new belt that hasn't stretched yet. There can also be slight manufacturing variations in the engine parts themselves. The stock cam gear timing mark-to-keyway relationship can vary as much as 2 deg ( see here -> http://www.lindseyracing.com/mm5/merchant.mvc?Screen=CTGY&Store_Code=LR&Category_Code=944CAMGEAR ). As long as it's very close, like within half a tooth, it should be fine. I've heard it can be set off a tooth one way or the other and not damage anything, but not much more than that.