need to know overall svda timing curves for programming

[trescojones]

I have built a computer and coil driver kit for my bus
(1973, dual PDSIT 34 carb, manual,1700)
and I have been searching for the timing information to program the computer with.
The dizzy as a vacuum SVDA 0231130001, i have seached for specifications but have found these buses arent listed with this dizzy at sites such as oldvolkshome.
so;
*Does anybody know where i can the timing information?,i need to make an rpm vs load map
*is the stock vacuum timing the very best,are there any adjustments worth doing?
If the same year,engine,model vehicle has another number distributor, couldnt i use its curves instead?
Also, the timing is split into descriptions of what the vacuum and centrifugal parts do at various rpm, am i right to presume you take the one with the most at a particular point as the overall advance curve?
I need an understanding of how load timing changes too, presumably when the advance range figures are quoted at things like 7-12deg etc this is the variable, and its a function performed by the vacuum?
thanks

[Wildthings]

Your present distributor is probably not stock for your application. Who knows if stock is the absolute best for your engine, that is why people put their vehicles on dynos so they can try and determine what is best..

You add the various advances to get the overall advance.

Static + centrifugal + vacuum = total advance

Note that static for most Type 4 distributors is 7.5* BTDC. For most DVDA dizzies use a static of 7.5* and ignore the retard function.

[trescojones]

thanks, this gives me something to work with

[Vince Waldon]

Here's an engineering challenge for bonus points: bolt on a knock sensor (the sensor used on MK2 and MK3 Golfs and Jettas is easy to access and junkyards are full of 'em) and do your advance closed-loop, like the big boys!
_________________
Vince Waldon Edmonton Alberta CANADA
1970 baywindow

[trescojones]

thats exactly what I'd like to do once Ive got it running Vince, map it myself to keep it about 4 deg ahead of ping all the time. Thanks for the tip about where to find them, i was looking at a $250 US bolt straight on unit when i found the kit i wanted to use is not made anymore. This could be much easier, have to get a secondhand MAP sensor anyway

[Vince Waldon]

They are right on the front of the block, next to the oil filter assembly if memory serves, one bolt and out they come, no need to roll in the mud like most stuff from the yard entails.

I've grabbed them in the past to make timing light adapters for diesels...work a treat and are cheap from the junkyard.
_________________
Vince Waldon Edmonton Alberta CANADA
1970 baywindow

[trescojones]

excellent thanks again, might get access to the manuals etc once i pull one to get the voltages impedance etc if needed. I wanna go coil per cylinder down the track, but perhaps after getting it going nicely.
I also want to instrument it pretty well, cyl temps,input manifold half pressures, fuel pressure, wideband EGO put it all in the glovebox so i can tune it and check every day but it isnt in my face all the time. Take all the guesswork out of tuning.
The programmable ignition computer,programming unit, and coil driver is from jaycar electronics, very cheap and pretty solid, can be tweaked out on the road with the programmer plugged in, built them all in 2 days