lets revisit timing

[Mattax]

@RustyRatRod @Mattax

Exactly.
Welding the inside , extending the springs into more tension.. ...wtf is he thinking.lol so we want a slow curve?
Putting the spring under tension and into its max resistance..uh no thanks.
The outside is where you would close it up.

Tony is a pants shitter

No. I disagree.
A little more tension on the primary spring is generally no big deal, especially on a non-stock engine where its going to have more initial and little higher idle rpm.
I've welded up slots on the outside only to file them open and redo it on the inside.

If you want less spring tension, then adjust it-
With most points, the tach drive, and the mallory YH distributor, bend the spring perch.

With typical Chrysler magnetic pickup distributors rotate the perch on its eccentric.

Don't even need to disassemble it again.

Less tension on the primary spring and the advance will begin at a lower rpm.

 

[Mattax]

Lets go over the different adjustments and what they do.

Here's a governor (aka slot plate) installed with its springs and weights.

1. RPM advance begins depends on the initial spring force on the wieght.
That spring force holding the wieght back depends on three things.
a. Spring rate.
b. Length spring (loop to loop).
c. How much the spring is stretched.

With a light primary spring like the factory used, a small change in stretch caused by welding the inside of the slots can easily be compensated for by adjusting the spring perch.
Factory primary springs tend to be about .75" loop to loop. Obviously they vary.

Lets compare with some other springs

The Gardner springs in the middle are about the same size but made of heavier wire.
They are close enough in length that with a little bending of the loops and the initial spring force can the be fine tuned with the perches so the advance starts immediately above idle rpm.
That's why in the distributor shown above a heavy primary spring can be used.

2. Advance rate above idle.
This is entirely dependent on the primary spring. If we want a faster or slower advance, the spring needs to be changed.

3. Shaping the advance at mid to high rpm.
The second weight moves out with the primary wieght because its locked into the slots. When its moved out far enough, the second spring joins in. Moving the secondary spring perch, or using a secondary spring with a different length loop changes the degrees of advance before the heavy spring applies force.

You can eyeball how many degrees into the advance before it contacts like I'm doing here with a tach drive distributor.

To bring the second stage in earlier, the tab type perch would be bent a little outward.

 

[Mattax]

Bottom Line.
The most important thing to do is measure the timing from an rpm as low possible to as high as one expects to run the engine.
Then make a decision on what to change or adjust.

Initial and total are almost meaningless without knowing the rpm for each.
^^^ This is the biggest mistake I see posted here. ^^^
Before making any changes its critical to know the rpm the advance begins, when it slows, and what rpm it seems to be "all in" and/or retards.
This why I don't like to say always weld the inside or always limit the outside.

Further, changes don't always do what people think they are going to do.
I learned that the hard way. Maybe everyone has to, but I post this stuff so people can see why.

 

[MOPAROFFICIAL]

No. I disagree.
A little more tension on the primary spring is generally no big deal, especially on a non-stock engine where its going to have more initial and little higher idle rpm.
I've welded up slots on the outside only to file them open and redo it on the inside.

If you want less spring tension, then adjust it-
With most points, the tach drive, and the mallory YH distributor, bend the spring perch.
View attachment 1715788634

With typical Chrysler magnetic pickup distributors rotate the perch on its eccentric.
View attachment 1715788638 View attachment 1715788641

Don't even need to disassemble it again.
View attachment 1715788639

View attachment 1715788640

Less tension on the primary spring and the advance will begin at a lower rpm.

If you remove the stiffer spring , with just the lighter spring , you can set it at 18 initial and get about 18 mechanical advance by around 1500rpm.
The light spring is done by the time you cross the intersection. The stiff slotted spring will lengthen the curve
Those things, some, didnt full adavance till 4800 rpm. You leave that spring and wels the inside, you take up the slot . It starts under tension.
I dont bother with any of that on a stock distributor anymore, I run an msd . I ground down and egg shaped nut to get the curve I find my motor likes. Typically the same or close to the last motor...because it's the same car. I use a blue spring iirr. If I were messing with stock dizzys I'd use a mr.gasket light spring where the heavy is and call it a day. They came up with one light or 2 because the timing bounces with a mere 200 rpm drastically with only one mr.gasket light or stock light and nothing else. You can do it how you like. I don't think we are that far apart.

 

[ir3333]

Thanks for all that. I prefer to weld the outsides. That's how Don Dulmage shows you how to do it. If anybody would know, it's him.

How did you come to know Don Dulmage Rusty? He is a much respected Racer with a lifetime of experience and lives not far from me. He is getting up in years and hasn't been out much in the
past couple of years.

 

[RustyRatRod]

How did you come to know Don Dulmage Rusty? He is a much respected Racer with a lifetime of experience and lives not far from me. He is getting up in years and hasn't been out much in the past couple of years.

I don't. I have his book. Old Reliable. He tells all about how to build a basically bulletproof 440 race engine the old school way. It's a badass book, too.

 

[RustyRatRod]

If you remove the stiffer spring , with just the lighter spring , you can set it at 18 initial and get about 18 mechanical advance by around 1500rpm.
The light spring is done by the time you cross the intersection. The stiff slotted spring will lengthen the curve
Those things, some, didnt full adavance till 4800 rpm. You leave that spring and wels the inside, you take up the slot . It starts under tension.
I dont bother with any of that on a stock distributor anymore, I run an msd . I ground down and egg shaped nut to get the curve I find my motor likes. Typically the same or close to the last motor...because it's the same car. I use a blue spring iirr. If I were messing with stock dizzys I'd use a mr.gasket light spring where the heavy is and call it a day. They came up with one light or 2 because the timing bounces with a mere 200 rpm drastically with only one mr.gasket light or stock light and nothing else. You can do it how you like. I don't think we are that far apart.

I used one light and one medium sprAng on mine. For me, that's always put it about right. I did get rid of the long loop sprAng, though.

 

[RustyRatRod]

Lets go over the different adjustments and what they do.

Here's a governor (aka slot plate) installed with its springs and weights.
View attachment 1715788656

View attachment 1715788643

1. RPM advance begins depends on the initial spring force on the wieght.
That spring force holding the wieght back depends on three things.
a. Spring rate.
b. Length spring (loop to loop).
c. How much the spring is stretched.

With a light primary spring like the factory used, a small change in stretch caused by welding the inside of the slots can easily be compensated for by adjusting the spring perch.
Factory primary springs tend to be about .75" loop to loop. Obviously they vary.
View attachment 1715788649

Lets compare with some other springs
View attachment 1715788651
The Gardner springs in the middle are about the same size but made of heavier wire.
They are close enough in length that with a little bending of the loops and the initial spring force can the be fine tuned with the perches so the advance starts immediately above idle rpm.
That's why in the distributor shown above a heavy primary spring can be used.

2. Advance rate above idle.
This is entirely dependent on the primary spring. If we want a faster or slower advance, the spring needs to be changed.

3. Shaping the advance at mid to high rpm.
The second weight moves out with the primary wieght because its locked into the slots. When its moved out far enough, the second spring joins in. Moving the secondary spring perch, or using a secondary spring with a different length loop changes the degrees of advance before the heavy spring applies force.

You can eyeball how many degrees into the advance before it contacts like I'm doing here with a tach drive distributor.
View attachment 1715788654

View attachment 1715788655

To bring the second stage in earlier, the tab type perch would be bent a little outward.

View attachment 1715788653

That's why mine comes in at 1800. I adjusted the pins the wrong way. lol I may yank the distributor a little later and readjust it.

 

[MOPAROFFICIAL]

No. I disagree.
A little more tension on the primary spring is generally no big deal, especially on a non-stock engine where its going to have more initial and little higher idle rpm.
I've welded up slots on the outside only to file them open and redo it on the inside.

If you want less spring tension, then adjust it-
With most points, the tach drive, and the mallory YH distributor, bend the spring perch.
View attachment 1715788634

With typical Chrysler magnetic pickup distributors rotate the perch on its eccentric.
View attachment 1715788638 View attachment 1715788641

Don't even need to disassemble it again.
View attachment 1715788639

View attachment 1715788640

Less tension on the primary spring and the advance will begin at a lower rpm.

You disagree from a hypothetical standpoint. I won't debate the uncertain because that's a fruitless venture.
Me? I want the advance early, most stick cars will. I dont want or need the final 2 degrees of a curve to come in 4000 rpms later after I've already been in wot for that time.
So with what you say... you're not wrong for what you're doing, It's just not right for what I'm doing...we have different needs.lol

 

[MOPAROFFICIAL]

I used one light and one medium sprAng on mine. For me, that's always put it about right. I did get rid of the long loop sprAng, though.

Yep. Remove heavy slotted spring and replace with one light spring. Full advance around 2400.
2 light springs is like 1200 full advance

 

[GTX JOHN]

As a rule of thumb on my Stock Eliminator cars I pick up 1% for ever degree of advance until
you get to much and I start laying down in last few feet.
As Altitude and Humidity go up I can run another degree for ever 1000 ft or 10% Humidity
But you must be rich enough on you jetting!!

When these cars were new = I removed the Heavy Spring and bent tab out
on the light one as far as possible with hitting

Goggle: John Irving Drag Racer
To see some of our stuff

 

[Mattax]

Yep. makes sense. That's what I got from John Soemer from when he ran stock eliminator. But when they went to electronics they found out just what I posted here. lets revisit timing

 

[92b]

We see this scenario on the dyno sometimes. Locked or welded HEI or locked or welded Msd distributors are common in circle track racing. when you check timing with these setups you will notice starting from idle the timing retards as rpms go up. How much it retards varies a little but they all retard. What you can run into is that the timing the motor wants at the top of the rpm range ends up being more timing than what the motor wants on the bottom end of the rpm range. Example 36 degrees at 6000 rpm and 40 degrees at 3000 rpm. I'm not aware of a way around this while still keeping the simplicity of a welded or locked distributor.

 

[Bewy]

Magnetic p/up dists suffer from distortion of flux wave & the timing retards as rpm increases.

More here:

www.worldphaco.net

 

[92b]

Magnetic p/up dists suffer from distortion of flux wave & the timing retards as rpm increases.

More here:

www.worldphaco.net

Wow, that is some detailed information. I can't imagine how much time was spent gathering that information and relaying it in text and pictures. That is someone who is truly dedicated.

 

[DrCharles]

There is also a finite delay through any electronic ignition from the trigger edge to the coil firing. As the RPM goes up, obviously the time per revolution goes down, and that delay is then a larger number of crank degrees. I think YR posted some figures a while back, some boxes were 1 degree per 1000 rpm or worse.

 

[Hot Metal]

Even stock 10:1 340s made more than they were advertised at. I think the realistic number was likely about 320. So going from “optimal” timing (call it 34-36 deg) and pulling 6 degrees out of it I am of the opinion that you would notice a difference in power.

Not about timing really here but that theory of them making more than 275 up to 320 stock is very debatable....my '71 340 s/strip cuda ran down the track back in the day and weight/mph said 301fwhp and that was with an ally intake 750DP, .484/284 cam and small tube hdrs. it ran real good@36 total on leaded 4 star fuel we had then which was approx 97 octane. Upped that to a .590 sft, 850DP and race hdrs and it was 367fwhp.