QUOTE(NJ914 @ May 4 2023, 12:49 PM)
Ed,
Appreciate your inputs on this Chart. The bottom of the chart is cut off and states:
"All but the first two and the last single entry were taken from tables in the factory manual. The others were taken from graphs in the factory manual. The advance curves on the graphs for those first two distributors start at 5 degrees, and increase by 11-15 degrees. Likewise the retard curves start at +5 degrees (advanced) and decrease by 8-10 degrees. However, the last [2.0] graph starts both the advance and retard curves from zero degrees.
So a note about "Total advance or retard is relative to the timing with no vacuum" or something to that effect is probably in order."
This is where I found it:
http://web.archive.org/web/20030202024600/...ww.dgi.net/914/Would really like your inputs on the programming of my 039 905 205B (which I'm guessing is the last row for the 2.0 noted unlabeled. (It is almost the same as the 205A above it anyway.)
Based on the 123 dist instructions, these points need to be doubled (assuming the chart is based on distributor rpm and not crankshaft).
Centrifugal:
0 deg @ 900rpm becomes 0 deg @ 1800rpm
9 deg @ 1500rpm becomes 18 deg @ 3000rpm
15 deg @ 2000rpm becomes 30 deg @ 4000rpm
22 deg @ 2800rpm becomes 44 deg @ 5600rpm
Vacuum:0 deg @ 108mmHg becomes 0 deg @ 15kPa and finally
0 deg @ (100-15) 85kPa7 deg @ 125mmHg becomes 14 deg @ 17kPa and finally
14 deg @ (100-17) 83kPaDoes this sound right to you?
Would really appreciate your inputs...
---
WARNING: Too many @ tags!---
I might be concerned about the all in number of 44 degrees. But only because I know nothing about your cars and what they should be running all in and at how many rpm.
So first thing to do is confirm whether the chart is crankshaft or distributor degrees.
In my opinion, (which doesn't mean much) normally some timing is needed at start up.
In the British car world the starting sweetspot is usually somewhere between 12 and 17 degrees.
Your manual should tell you if they are referring to distributor degrees or crankshaft degrees. We always refer to crankcase degrees which are double the distributor degrees.
As for the Vacuum I would not use vacuum retard only vacuum advance. Normally the map curve in the app is good and adds 10 degrees when the inches of mercury call for it. You could make that value whatever you like.