Have a stock '65 170, w/thick head gasket (so lower compression).
Is an automatic, but has cars original '64 Loadamatic dizzy for a manual tranny (checked the part # C4...-Z).
Run the autolite with a 67 jet.
Run points. (Dwell doesn't vary much at all, maybe half a degree at most).
I hooked up a vacuum pump to the diaphram to see how much advance I was getting total, and it was 30.5 degrees (just advance, not counting base).
The dizzy plate is stopped by the secondary spring post - there's still some space between the primary spring post and the cut-out for it.
With the spring settings I have now I'm seeing 30 degress of advance at 2500 rpm (steady throttle) w/5.5" of vacuum.
I've run the base timing at 10 and 12 and it seems about the same performance-wise, a little better low-end w/12 degrees.
Questions:
For this engine/setup, have I got the max advance where I want it? Is 40-42 total at 2500 ball park? Do I want more? Do I want it sooner/later? [or what are ways to make those judgemenets - just driving it?]
Should I file the dizzy plate's post slot so that it will advance a bit more?
[Is this the difference between the manual and auto dizzy- the plate cut outs providing max advance?]
Note: It's hard to tell when this thing is pinging. I run 91 octane when I can find it, but will fill up with 93 and then add some 89 along the way when I can't find the 91.
matt
background
Originally with the spring tension at mid to loose the max advance was reached at 4-5" of vacuum which I was seeing around 1800-2000 RPM.
One of the issues I was seeing was that what I think was too much advance at lower revs- something like @1200 rpm was seeing 28 degrees.
When I set the base timing at 6 it had seemed like I had better power at highway speeds, and lower bottom end. When I set the base to 12 it seemed the oppositte.
So, I set the spring settings (by moving the eliptical post) to the most tension, which gave me more range. I figure if the curve is flattened out a bit then I can raise the base and not get too much too soon.
Is an automatic, but has cars original '64 Loadamatic dizzy for a manual tranny (checked the part # C4...-Z).
Run the autolite with a 67 jet.
Run points. (Dwell doesn't vary much at all, maybe half a degree at most).
I hooked up a vacuum pump to the diaphram to see how much advance I was getting total, and it was 30.5 degrees (just advance, not counting base).
The dizzy plate is stopped by the secondary spring post - there's still some space between the primary spring post and the cut-out for it.
With the spring settings I have now I'm seeing 30 degress of advance at 2500 rpm (steady throttle) w/5.5" of vacuum.
I've run the base timing at 10 and 12 and it seems about the same performance-wise, a little better low-end w/12 degrees.
Questions:
For this engine/setup, have I got the max advance where I want it? Is 40-42 total at 2500 ball park? Do I want more? Do I want it sooner/later? [or what are ways to make those judgemenets - just driving it?]
Should I file the dizzy plate's post slot so that it will advance a bit more?
[Is this the difference between the manual and auto dizzy- the plate cut outs providing max advance?]
Note: It's hard to tell when this thing is pinging. I run 91 octane when I can find it, but will fill up with 93 and then add some 89 along the way when I can't find the 91.
matt
background
Originally with the spring tension at mid to loose the max advance was reached at 4-5" of vacuum which I was seeing around 1800-2000 RPM.
One of the issues I was seeing was that what I think was too much advance at lower revs- something like @1200 rpm was seeing 28 degrees.
When I set the base timing at 6 it had seemed like I had better power at highway speeds, and lower bottom end. When I set the base to 12 it seemed the oppositte.
So, I set the spring settings (by moving the eliptical post) to the most tension, which gave me more range. I figure if the curve is flattened out a bit then I can raise the base and not get too much too soon.
