Would revhead001 perhaps be able to recommend a guy in South Africa?

pm revhead001, he recomended a place to me, its out ringwood way or similar.

my lpg guy said my graph was ok, just reduce the total advance to 15 deg. either that or lock it.

i think i might just lock it- economy on the high way wont matter much with LPG

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.

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.

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

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

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.

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...

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

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