Does this help?

http://www.licmotorsports.com/produc...sti_lic-061505

 

Excellent information, thank you, makes sense now for when using non adjustable cam pullies.

 

Sorry Duncan, but what a ridiculous statement.

 

So they are saying the OEM tensioner is not capible of adjusting following a few thousands difference?

 

Try this explanation. I admit, it's a difficult adjustment to get your head around: 03-01-2011, 08:54 AM
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"Yeah I didn't get it at first Stace,

But it affectively changes the timing belt length between the crank & and cams.

When you adjust the upper idler on the RH side,...it ends up adjusting all of the cams. (everything between it and the tensioner,... (the tensioner being the only thing that takes up, or gives out slack)).

The lower idler on the RH side is after the RH side cams but before the LH side cams,.. and just like the top one,.. it adjusts everything between it and the tensioner. And being that only the LH side cams are located between it and the tensioner,....adjusting that lower idler eccentric only affects the LH side cams.

Practical example:
Lets say you've narrowed your engine by decking the heads and the block (after a rebuild or two). Doing this will retard all 4 of the cams. And because the belt goes past both heads before passing the tensioner (where the resulting slack is taken up) the LH side will be off twice as much as the RH side.

So if your narrowed engine has caused your RH side cams to become retarded by 2 degrees,...your LH side cams will be retarded 4 degrees. You can just buy one eccentric for the top idler... and crank it in (pushing the belt downwards) until any one of the cams has advanced 3 degrees (All the cams wil be advancing the same amount as you rotate the upper adjuster). Your RH side will now advance by 3 degrees to become 1 degree advanced from factory, and the LH side will improve from 4 deg retarded to only 1 deg retarded. Close enough.

If you're a stickler for perfection,..you can get two adjusters and adjust them each +2 degrees & have both sides back to the zero reference."

 

Hmmm, theory understood, but I dont buy that the amount of 'narrowing' we are talking about would account for the above mentioned retard.

I may be wrong though as I am basing this on my gut feeling and not calculations...