John02SS

iTrader: (47)

I've seen a few post about adding 2 points of timing from 400-1000 can help with the idle on camshaft cars. Is this due to the timing leaning the mixture out some. Could the same result be had from modifying the VE table or does the extra timing have another purpose? Thanks guys!

John

Bink

Cammed cars often have more overlap than stock. Result is a more dilute, heterogeneous mixture (Intake air-fuel mixed with exhaust gases) at idle. Sparking a little earlier will often allow for a more complete burn of the mixture. Greater burn/combustion results in increased cylinder pressure.
So, increasing timing gives a little more time for cylinder pressures to build at idle RPM. The increased energy of combustion provides for a more stable idle.
Hope this helps some. FWIW.
joel

John02SS

iTrader: (47)

Is the 2 points enough or too much. I've seen where some guys added 2 up to 800 and only 1 at 1000 rom. Thanks for the explanation!

Slowhawk

iTrader: (12)

Here is a simple answer.If you watch your timing at idle ,you'll see the timing jumping around.What you want to do is stop that and even out the timing.A easy way is to set the idle columns the same like set 400rpm column to 22 degrees,800rpm to 24,1000rpm to 24,1200 to 24,1600 to 28, ect.
This will help your idle smooth out.

Cal

iTrader: (1)

I added 4 degrees of idle timing to mine; that seemed to smooth out a lot of the cam lope and just improve the idle quality in general. This is the most I've heard of anyone adding; too much can make the idle unstable or surge also, particulary with an automatic car. I have an M6; I think 4 degrees would be to much with an A4; but what the hey, try it, if it's not good you back it out plus you have learned from the experiance.

John02SS

iTrader: (47)

Cal,
Did you add it from 400-1000 or in a different range. Thanks.

John02SS

iTrader: (47)

bump.