Effect of crankshaft timing variation

[ymz]

I wonder if anyone has an opinion (or can find a post) about how minute variations in crankshaft vs camshaft + injection pump timing affect performance.

Reason for asking... one of our cars (ALH) has an aftermarket flywheel with no TDC mark other than one made by hand using a marker some time in the past. This car doesn't have as good fuel economy as our other one, although the better MPG car has a tune and .205 nozzles (and is driven accordingly). I was wondering if that hand-made TDC mark may be off a few degrees (not enough to show up with a dial indicator, but a flywheel tooth or two)... I know about the mark on the harmonic balancer, and the handmade flywheel mark is sync'ed with that one, but there's still the possibility of a few degrees' discrepancy...

Comments?

Yuri

 

[Rembrant]

I wonder if anyone has an opinion (or can find a post) about how minute variations in crankshaft vs camshaft + injection pump timing affect performance.

Comments?

Yuri

I can't comment much...but I do know that the base timing can be off. I've seen it with my own car ('00 NB) when purchased, and Whitedog started a thread about it here:

http://forums.tdiclub.com/showthread.php?t=455863

I only bought my car like that...I didn't drive it like that, so now that I have it all dialed in correctly, I can't tell you how much difference it has made. I also made a ton of other changes, so I really would have no idea.

 

[Fix_Until_Broke]

This thread has the most info on the topic you're curious about...

http://forums.tdiclub.com/showthread.php?t=339474

 

[ymz]

Great thread!!! Now to find my bottle of Aspirins...

I think that if there's any question as to the reliability of the flywheel marking, retarding the crank (which equals advancing the cam) a flywheel tooth or so is the way to go... (at least, that's how it looks now - but I'm tired... will re-read in the morning...)

Thanks!

Yuri