maximum total advance

[tdafforn]

Hi All,
now I have the ignition running using a megasquirt ECU I can play with the advance curve.
have already moved to the one SteveWW mentioned in a recent mail.
This tops out at 33 degrees max total advance.
Have to say, it seems to give better torque and freer reving (set of pants measurement )
Now, what I want to know is how far people tend to take max advance on standard UK unleaded fuel?
Cheers
Tim

[paddy]

Nobody replied to this. I'm not an expert, but I did happen to discuss this with my friendly local rolling road man just before you asked the question. He said not to go beyond 33 or 34 degrees. We were talking about a standard engine with Webers using super unleaded with Valvemaster plus and no other additives. I don't know which of these factors might change the answer. (There was a thread not long ago suggesting the reasoning behind the timing being different on Strombergs vs Webers.)

Paddy

[rgh0]

My esperience says the following

Standard premium unleaded 95 to 98 octane in a weber road engine at around 10:1 to 10.5 to 1 maximum advance required around 25 to 28 crank degrees total static plus centrifugal.

Stromberg engine with above fuel and compression specs around 30 to 32 degrees total. The higher max advance required due to the poorer volumetric efficiency of this head / carbs at high revs.

A Weber race engine on slower burning avgas but higher volumetric efficency and higher compression of 12 to 13 to 1 and higher max revs needs around 30 to 31 degrees.

cheers
Rohan

[thegman]

Sorry to ressurect and old thread but.. I've just installed a 123 dizzy. Bit confused by all the timing curves out there in the forum's - most of which seem scanned from original manuals.

I'm running a pretty hot engine including stage 2 head and webers. From what I read I am aiming for about 32 degrees at 4000 - why wouldn't I just have two timing points and let the dizzy interpolate the rest?

500 - 10 deg
4000 - 32 degrees

Anybody setup a 123 or squirt on a fast road engine and care to share a curve?

[elanman999]

I can send you a map from my Emerald ECU but it won't be a lot of good unless your 123 has a engine load input. For Webers a TPS is best. You will then be able to run more advance when in light load conditions which for a road engine is better for fuel economy.
PM me your email add if this is going to help. The Emerald software is free to download from their web site.

Cheers
John

[thegman]

Thanks John - probably not worth it but I appreciate the reply

My setup is very old school apart from the 123. It seems to be running very nicely with a simple straight line from to 30 degrees at 3500 from 10 at 1000 rpm.