hey guys
i need to get my electronic distributor regraphed for my a15. What does it actually involve when you regraph a distributor and what do i need to know to regraph it? (cam specs?) also is there any reputable shops in melbourne that can perform this?
cheers

From memory it involves changing the flywhights on the mechanical advance to suit your needs. I think lighter weights means the advance will come in later and slower but I am unsure. The dude should only need to know what ever mods you have done to your donk and most importantly what fuel you will be running on everyday. He will adjust the advance curve to match the fuel you are using. I dont know of anywhere in melbourne but I got my old 351 CLEVO dizzy done at SAMS PERFORMANCE in SYDNEY. Ring up an LPG conversion mob like GasResearch Aust and ask them where they get their dizzys done because when you convert a car to straight LPG it is highly reccomended to get the dizzy regraphed. Good Luck

cheers mate. anybody know where i can get it done in melbourne?

anybody know where to get a distributor regraphed in melbourne, preferably in the S-E suburbs. cheers

supposedly lpg doesn't take advantage of much change in timing, but to fix what was done to the timing for emissions perhaps...

it's changing the springs and weights basically...

Changing the spring is much easier than finding new weights I'm sure. I guess you could also weld material onto the weights if you really needed to.
The lighter the spring the faster the ignition will advance. Get a dial back timing light and some suitable springs and do some experimenting. I put a lighter spring on one side of my stock a12 dizzy and it seemed to make a big difference They can definitely use a more aggressive advance curve.
I think I used an advance spring from a kit I had laying around to tune a GM HEI distributor.

there is no point playing with weights and springs till you know where you are going with your curve

first you need to know what duration your cam is to get your static advance and idle rpm settings 270=10/12@600/700rpm
280=12/14@900/1100rpm
290=14/16@1000/1200rpm
300=16/19@1100/1400rpm

then you need to estimate your total advance wich is relative to your combustion chamber (has to do with burn rate)

open wedge=36 to 38 deg
heart shaped=34 to 35 deg
closed chamber=38 to 40 deg

then you need a distributer recurving machine to spin the dissy till you get it advancing at your requirments

thanks for the info guys its all very helpful. anyone in melbourne had theres regraphed and know where to go?

Quote:

I've got a 280 deg cam in my mildly worked A14 with A12GX head.
What I have noticed is that I get much better idling and bottom-end performance when advancing the timing to about 10 deg. and that it really does not want to idle anything below 900rpm? Coincidence?

According to the list above, does it mean that my 280 deg cam would prefer to idle at 900-1100rpm with 12-14 deg timing?

By static advance, is it meant that you adjust the timing statically without the motor running or at idle with or without the vacuum advance connected?

And at fully advanced (mech and vacuum) I would need 34-35 deg timing.

Am I interpreting this correct? I know this would only be a base line, and that the final settings would need to be determined on the dyno.

While we are on this subject, does it matter if you are running standard carb, dual Hitachi's/SU, DCOE or that bike carbs?

The particular motor of MHDat is my old motor with the Flat Top Hitachi's on. We just overhauled the bottom end, balanced it and fitted the 280 cam.