WWDiesel wrote:
Most interesting! Like those "pinned" cam pulleys...
I bet if this was a true 'test mule', it'd have quick change timing. They'd be able to change up cam timing with offset keys or what I'm guessing is an eccentric 'pin'. Adjust the cam centerlines with a KNOWN offset key, put some miles on it, test it for drivability, performance, economy, smog.. etc until they got a good happy medium. Take those results and they know what the cam centerline will be for the locating pin hole we all have in the mass produced version.
Keying @ the factory would've added lots of assembly time, and a disaster in the 'field'. Can you imagine the confusion about 'offset' keys would cause! Heck, half the folks in here don't understand a simple 3 pin alignment procedure..
Every time a major component is changed, (head, crank and or sprocket, or anything that COULD 'change' the distance between crank centerline, and cam centerlines) We'd have to measure 'cam centerline', and adjust accordingly. As in checking the liner protrusion for any evidence of 'shrinking' back into the block, measuring cam centerline would also be prudent.
Install the timing belt, make sure the belt is tight, and seated down in the cogs
1.Put a degree wheel on the crank, and measure amount of 'lift' at a certain amount of crank rotation- A dial indicator to measure lifter movement is required. (intake has to come off.)
2.Take timing belt back off, and install the proper offset keys to adjust.
3. Re assemble, and re-check it all over again.
Thank goodness all is needed now is to simply put in the locator pins, and tighten up the cam sprocket bolts!!
It's the most elegant and simple way to overcome any manufacturing variances, both in Italy, or in someone's barn!