Author Topic: Timing advance weight spring choices.  (Read 1149 times)

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cleandan

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Timing advance weight spring choices.
« on: September 02, 2022, 09:45:31 AM »
I am working on a 1965 K-Code 289.
I have been chasing, and repairing, various ignition troubles.

While I had the distributor apart to check the advance stops and springs I noticed this particular set up has the heaviest spring I have ever seen on one side, and just about the lightest spring on the other.

Is this normal/factory for a K-Code?
I don't remember ever seeing this wide disparity of spring weights in any distributor before, but one thing I seem to remember is I don't really remember all that well anymore, so this could be fairly normal.

Does anyone know what advance springs were installed as factory K-Code items?

BattlestarGalactic

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Re: Timing advance weight spring choices.
« Reply #1 on: September 02, 2022, 11:15:20 AM »
Interesting thought.  Why two different springs?  Would the light one be shorter and the heavier longer so it doesn't react as fast but only once it starts into the rpm curve giving you a quick curve then slows down.

I've typically just put the lightest in to get it all in quickly.
Larry

TJ

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Re: Timing advance weight spring choices.
« Reply #2 on: September 02, 2022, 12:40:14 PM »
Been a while but I believe pertronix dizzies allow you to use different strength springs on each side to customize the rate of advance.

1964Fastback

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Re: Timing advance weight spring choices.
« Reply #3 on: September 02, 2022, 01:57:02 PM »
I had to buy a generic FE distributor from Autozone while on the road.  Later I went to tune it and it seemed to have only 10 degrees of advance, all in by 1900 RPM.  I think I revved it to 3000 or so with no change.  I took it apart and measured the slot width and it should have had like 30 degrees of advance at the crank, 15 at the distributor.  But it had one medium spring and one really heavy spring, so I was only seeing the advance until it hit the heavy spring.  I suppose maybe if I'd I'd kept going, I might have seen more advance in the 4000-6000 range.  :)

I ended up welding the slot to give 20 degrees crank advance and replaced the heavy spring with one of the light Mr. Gasket springs (925D kit).  I left the other medium spring in place.  The 20 degrees advance is all in by 3800 which is still a little high.  I should bend the pins in a little sometime and try to get it all in a bit sooner.

Pat
1964 Galaxie 500 2 dr Fastback, 390, 4 speed, Indianapolis Indiana

thatdarncat

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Re: Timing advance weight spring choices.
« Reply #4 on: September 02, 2022, 02:01:44 PM »
As you’re probably aware there is a primary & secondary spring on each. There are literally dozens of different springs Ford had available back in the day. The original springs used for each distributor are listed in the Ford Parts book, along with the other distributor parts (different advance slot cams, and so forth). Unfortunately if I remember the Ford Parts book will just give the part number for the different spring, and not specs as far as spring rate, number of coils etc. I’m sure somewhere buried in the Ford engineering files the actual specs of each spring are recorded. I’m away from my parts books, I can look later if you want, I’d need to know the actual distributor I.D. number, but like I said, it will probably just give me the spring part number. Each year Ford Shop manual for the vehicle usually has the distributor “curve” listed, so a person with a distributor machine would be able to check if their distributor is set to factory spec, but of course a modified engine most likely will want a different timing curve. If you look in the distributor section of the shop manual you will see there are many different distributor curves used. And yes, you can often see a big difference between the two springs.

*edited to add - even on a factory performance application, like a 289 HiPo, 427, etc., the Ford engineers were still thinking about warranty considerations, and other compromises. The guys who know how to modify things like the distributor curve, whether by experience or trial & error, or backdoor tips from the factory engineers,  were the ones who often ran a little better at the track.
« Last Edit: September 02, 2022, 02:09:41 PM by thatdarncat »
Kevin Rolph

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rockhouse66

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Re: Timing advance weight spring choices.
« Reply #5 on: September 03, 2022, 10:09:59 AM »
I agree with everything Kevin posted - the spring numbers are in the parts books but no specs.  The gadget with the two slots and the points cam is the reluctor.  There should be two slot widths, marked something like 10 and 15 or 13 and 18.  The K code engine should like the narrower slot and a pretty quick advance curve.  Depends though on rear gear, state of tune of the engine, etc.


I have found the Mr. Gasket springs to be too light almost all of the time on the FE distributors that I work on.  The light spring controls the first 2/3 or 3/4 of the curve and the heavy spring is just loose, then comes into play to slow the curve as the engine speed increases.  If you run something like the 10 degree slot in the reluctor you will have 20 degrees of mechanical advance at the crank so will be running about 16 degrees of initial spark advance.  With this much initial, I find the Mr. Gasket spring brings the advance in so fast that the initial plus mechanical advance happens too early (low engine speed).  Very hard to say without a distributor machine or lots of trial and error in the car with a timing light and repeated removal of the distributor points plate to juggle springs.
Jim

Ford428CJ

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Re: Timing advance weight spring choices.
« Reply #6 on: September 07, 2022, 10:11:48 PM »
I never have that problem with Mr Gasket springs. I get it to come in when I want. I’ve done a ton of FE distributors over the years. And the advance rate is close to being spot on!  It I do quite of bit of blueprinting to the distributor….
Wes Adams FORD428CJ 
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winr1

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Re: Timing advance weight spring choices.
« Reply #7 on: September 16, 2022, 09:34:58 PM »
My junk is street only so I delay total a bit

I use the factory Ford light spring and 1 Mr Gasket spring

You can bend the tabs in the distributor as said above to vary the tension

Add timing marks to ya balancer or timing tape and use a timing light and rpm meter ta see


Ricky.


fryedaddy

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Re: Timing advance weight spring choices.
« Reply #8 on: September 17, 2022, 01:34:48 PM »
When i tried the two light springs it tried to advance at idle making it hard to time,so i put one heavier spring and one lite spring and it worked perfect
1966 comet caliente 428 4 speed owned since 1983                                                 1973 f250 ranger xlt 360 4 speed papaw bought new

cleandan

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Re: Timing advance weight spring choices.
« Reply #9 on: September 19, 2022, 06:51:47 AM »
When i tried the two light springs it tried to advance at idle making it hard to time,so i put one heavier spring and one lite spring and it worked perfect

The idle area is where I find bending the tabs just a bit can give me a very specific advance starting rpm.
I will install springs that get me my total at the rpm I desire.
Then I look at the curve to see how it advances across the rpm range and if it is good I leave those springs in.
Last I will move the tabs in or out to adjust the advance start rpm, usually about 200 rpm above idle for a street car.
Then I finish by checking it all once again to be sure the tab bending did not alter the other aspects.

Many times I find the springs are loose, or slack, at idle when I first start tuning an unknown distributor, and this usually results in a variable idle rpm to some extent.

Thanks for all the input. I still don't know why this distributor had such a huge disparity in advance spring weights but all that has been taken care of and this particular 57 year old, 53,000 mile original runs pretty good now.