Hey guys,

I have seen mention in a few posts now about advancing the timing on a s3 4.2 to give it more low down power off the line. My 3 questions about this are as follows

1) Does it affect fuel?? Meaning fuel consumption and also required octane rating?

2) How do you do it??

3) How do you know if its already done by a PO?

Thanks guys

Cheers,
Richard.

 

Are you talking about advancing the camshaft timing or advancing the ignition timing? Or both?

Ignition timing is easy to change. Loosen the distributor clamp and turn the distributor. To advance the timing turn the distributor in the opposition direction that the rotor turns. Use a timing light to measure before and after. If you get pinging/pinking you'll need higher octane fuel.

Advancing cam timing is a bit more involved.

I start with the engine at TDC and the cams "straight up", as they should
be, of course. Now turn the engine so 8º BTDC shows on the timing scale.
Then disengage the cam drive plates from the gears and turn the cams back to
their "straight up" position. That's it. You've advanced the cam timing 4º.

For 3º of cam advance you'd turn the engine so that 6º BTDC was showing on
the timing scale. For 2º advance you'd want 4º BTDC on the timing scale.

Some guys eyeball the "straight up" notch on the cams but I use a camshaft
gauge plate...only a few dollars from a Jag supplier.


Cheers
DD

 

One can also mess around with the sprigs and slots and weights in the mechanical advance in the distributor body. Object is often to bring in the advance earlier on the rpm scale.


Just how much advance over stock an engine will accept varies. Largely by the cleanliness or lack of the combustion chamber.


Power timing:


Bump up a couple of degrees, and drive. Do this til you get a ping. Back down just enough to eliminate it.


Caveat, too much can melt alloys! that means pistons, not good.


Carl

 

Thanks guys. It is the camshaft timing that I am asking about. Gives me a good idea.

 

Doug, just reconning a 3.4 and remembered that I had seen this somewhere. From what I read above I assume you are talking about advancing both cams by a set amount? I thought in the back of my mind that the exhaust was treated differently?

 

Hmmmm.

My memory is being taxed here.

If anything the exhaust cam is left alone....but I think advancing it along with the intake cam is benign.

I'll look up some old notes and try to clarify

Cheers
DD

 

Looking back over 10-12 year discussions elsewhere *both* camshafts are advanced an equal amount

Cheers
DD