When centrifugal advance springs get old

When centrifugal advance springs get old, do they get stiff and therefor not advance the timing as much as they should or get soft and advance too much /too early (at a lower rpm).

My guess is they get stiff.

This is on a 91 Ford 5.8 L the timing should be 10 Deg BTDC at Idle up to 1000 rpm then increase up to 30 deg total advance at 5000 rpm. It should be about 19 deg total at 2000 rpm. I was getting much less that that at 2000 rpm.

[FONT=Arial, Helvetica, sans-serif]Do I have old stiff springs? [/FONT]

[FONT=Arial, Helvetica, sans-serif]BTW I'm just trying to get back to the OEM advance curve. I'm not trying to change anything. There are a few pretty good posts on here about the dangers of playing around with the advance curves.

[/FONT]Thanks

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Kipmc7 said:

When centrifugal advance springs get old, do they get stiff and therefor not advance the timing as much as they should or get soft and advance too much /too early (at a lower rpm).

My guess is they get stiff.
In most cases it's rust/corrosion that affects the spring value.
Compromised spring value will allow for early advance (baring that the flyweights are free).

This is on a 91 Ford 5.8 L the timing should be 10 Deg BTDC at Idle up to 1000 rpm then increase up to 30 deg total advance at 5000 rpm. It should be about 19 deg total at 2000 rpm. I was getting much less that that at 2000 rpm.


Do I have old stiff springs?
It may be possible that the flyweights themselves have rusted at the pivot area, and have become sticky.

BTW I'm just trying to get back to the OEM advance curve. I'm not trying to change anything.
Wise move!

There are a few pretty good posts on here about the dangers of playing around with the advance curves.
Yes.... I agree!
If you have a shop in your area that has a Sun, Allen or King machine, they can safely make the corrections for you.
They would need to see your OEM Marine ignition curve.

Click to expand...

I responded to the same question on IBoats but in any case I’d think it’s more an issue of rusty crud restricting the movement of the weights, remove the point plate (2 screws) and clean it out with a bit of carb cleanse and compressed air, then lube them with some motor oil.

I'll do that right now...

The seemed to move freely but I sprayed them with WD40 and worked them back and forth. Then I greased them. They do seem to allow 10 deg of advance at the distributor which would result in 20 deg at the crankshaft. I do see that there are 2 different springs one is made from thicker wire. I also see that the slots in the plastic piece are different widths so you would have to get the correct spring with the correct slot. Is there a way to tell? They could be reversed.