Hi all,

i saw in a different post the mentioning of a distributor dial as tool.
I remember when I learned mechanic there was a little motor to speed up a distri to see/check the advance curve for the mechanical advance.
I've checked a good while ago in the shop manual and I found the values in there utterly useless. It describes the advance from 500rpm upwards, so it can only be used with such a tool. I was playing around with springs etc but it's hard to change/drive and feel any differenmce. I'm deaf to pinging, so is there somethign like an advance curve that I can go on? i can measure static and dynamic advance.
I currently have full advance at 35* without vacuum, but that's already at under 3000 rpm (something like 2800). have to re-check.
I believe that's a bit low so I changed to a bit heavier springs, but that causes the mech advance to kick in only after 1500rpm. under 1500 it stays at same advance as set for idle (750).
Any ideas or values to go after?

Kalli

 

You don't have to use the Sun Distributor Machine, you can use your engine:P All you need is a tach and a timing light. You just disconnect and plug the vacuum advance and check the mechanical advance at different rpm's.

Total advance of 35* @ 2800 is probably a hair on the high side, but I wouldn't worry about it if you didn't notice any problems. A lot of people say they don't know what pinging sounds like, but it's really obvious once you hear it. Sounds like somebody's rattling a can of marbles under the hood.

 

I am at full advance at 3000rpm. I am not sure what other run, but that is working for me so far. As for timing under 1500, if you look at the MSD datasheet on timing curves, timing should not change much under 1200 or so. After that, the amount of spring pressure is going to advance things faster or slower. What kinda of dizzy do you have? Have you looked at the timing curve graphs and tried to match what you want to what the can do with given spring and timing stop bushings?

Here is a link the the curve for my MSD distributor. Your's is going to be different, but it will give you an idea of what can be done.
http://www.msdignition.com/uploadedF...structions.pdf

I started with the stock blue advance bushing and the stock 2 heavy silver springs. This gave me total advance at 4000 with about 22* of timing advance above initial (Curve A). I wanted more timing and quicker, so I put in a Silver timing bushing and a light silver/light blue springs. That gives me about 26* of timing advance above initial at 3000 rpm (Curve E). As you can see, under 1200, there is little change in timing which is good for me b/c I idle at 1200! Besides, at low rpm, you are setting your initial timing for what you need. You really do not need timing advance to come in THAT quickly. If you want more timing down low, just increase the initial timing and then install a lower advance timing bushing to prevent too much timing at the top end. Keep in mind that I am not running any vacuum advance...all mechanical.

 

Gah, idle at 1200? That'd drive me nuts:P

 

hell ya. I'd go insane as well with 1200 idle. But thank you both. I'll try the heavier springs and increase initial timing a tad. see what that does.