So one fine day, a few years back, I had one of those 'Eureka' moments.

(We have those a lot here in California -  "Eureka!" is our state motto.)

I realized the spark scatter I was seeing when setting my timing coincided perfectly with a sorta soft spot in the transition between idle and full-on throttle.

Soft spots like that are all 'sorta'. We don't really want to admit they exist.

We blame them on temporary things - dirt in the jets, bad gas, too much time since the last tune, sun spots, etc. etc. Deny, deny, deny.

Anyway, way back then, I decided to man up and do something about the sorta soft spot. I put two Kelloggs box tops and 50 cents in coin in the mail, and two weeks later, a Magnaspark II showed up in my mailbox.

Like many folks had been saying, that did the trick. My timing mark was now suddenly visible across the whole rev range and the engine was smoother between idle and the fat part of the torque curve.

Well, sorta. There may have still been just a tiny hesitation there. Or maybe it was just bad gas.

Anyway, ever since then, I've been thinking about those little sets of advance springs they ship with the Magnaspark. They install the medium (light silver) set by default and since everyone's in a big hurry to hook up their new toy when they open the box, no one messes around with any of the other springs right off, right?

We put them back in the box and mostly forget about them.

Well, I got to thinking if the softer springs bring on more spark advance sooner and the 'fat part' of the torque curve happens at full advance, maybe a little more advance down low could be a good thing.

And damned if it wasn't. On my engine, at least - a two-liter with Weber 40's.

I tried mixing one of the 'blue' springs with the 'light silver' ones (they don't have to match) and, well, Eureka ! It made quite a difference. The transition is a lot smoother and it pulls stronger off idle. (Remember, softer springs make the advance curve steeper, but leave the max advance where it was set before the swap.)

MagnasparkSprings

 

With folks so hung up on what's wrong with their carbs, it's really hard to overemphasize how important solid spark and the right advance curve are to an engine that has no computers to look after its well being.

It's dopey simple to pop in different springs if you want to experiment. They're easy to get to, and it takes maybe 10 minutes. Just remember to check max advance after the change, just in case.

Some day, someone will invent a system that lets you fine tune the whole advance curve just by plugging in a laptop computer to some magic black box - without any springs at all.

That's gonna be great.

 

 

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Good post, Mitch-- but you can take this one step further for very short money.

DannyP posted:

Mitch, first of all, great post. Stan says this all the time: 90% of "carb" problems are "spark" problems.

CB already has your laptop wish: the Black Box.

Or, you could do what I did, and cut out the distributor entirely.

https://wiki.autosportlabs.com/MegaJolt_Lite_Jr.

Thanks for continuing to bang this drum for me, @DannyP, as I sometimes feel like I'm out here wearing animal furs and eating locusts, and sounding like a zealot regarding this topic. Perhaps someday someone will ask for my head on a platter, but until that day comes, I'm going to have to pipe up on threads like this one.

I'm not sure what it will take to get this out there so that people will listen, as there's a limited number of different ways to say it. I'm thinking of printing tee-shirts and giving them away, or getting the message tatooed on my forehead:

90% of "carb" problems are "spark" problems.

Everybody bags on Webers and Dellortos, blaming them for everything bad-- but it's really the spark that is 90+% of the "not quite right" problem. Electronically controlling spark in an engine isn't just low-hanging fruit-- it's fruit that is perfectly ripe, unblemished, and has fallen washed and sliced, directly on the plate. It's the single greatest advancement in engine operation in the last 50 years (and there have been some amazing advancements). It's having your cake and eating it too.

The CB Black Box is as simple as it's ever going to get. It can set it up for a perfect "all mechanical" (RPM only) spark curve, or allows vacuum advance with the kind of adjustability one can only dream of with springs and weights. Using one allows the timid or retro-purist to retain the 009, 009 clone, MagnaSpark (or whatever other distributor is back there).

It's $200, and an amazing bit of kit for the money. 

 

 

 

First, thanks for all of the kind words, folks. I didn't intend to write a manifesto.

And yeah, the 'black box' thing was a wise-butted, mostly failed attempt at irony.

Sometimes I think of dudes like Danny and Stan as our astronauts - space walking out there on the fringes of the known universe, discovering how things will be in the future for the rest of us back here on earth.

I think more of us don't do the magic black box because - true or not - it just seems a little too daunting to try in the real world. Lock down dizzies. Crank fire sensors. Computer programming. What, like I've got to learn Fortran or Cobol or something? If springs and weights were good enough for grandpa, dadgummit, they'll serve me just fine, thank you.

What it's easy to forget is that, in the old days, there wasn't just the trusty old Bosch 009. There was an 010 and an 020, and a whole shipload of different Boshees for all the different 356 motors and various combinations of cam, vacuum advance, no vacuum, or even vacuum retard.

Every time there was a new motor, with different advance curve requirements, they had to build a new dizzy with different springs and weights and compensating circuits. Grandpa didn't have it so easy.

Another annoyance is how used our ears have become to listening to the perfection of modern motors. Almost any car built in the past 15 years starts up from dead cold to an instant purr and stays that way as the car warms up, in any weather, under any load. Our ears are maybe too aware of any falter in these antique engines of ours.

My main reason for posting here was to remind folks there's an often forgotten fix to try for the many of us with CB dizzies who aren't quite ready for the black box.

 

Stan Galat posted:

Good post, Mitch-- but you can take this one step further for very short money.

DannyP posted:

Mitch, first of all, great post. Stan says this all the time: 90% of "carb" problems are "spark" problems.

CB already has your laptop wish: the Black Box.

Or, you could do what I did, and cut out the distributor entirely.

https://wiki.autosportlabs.com/MegaJolt_Lite_Jr.

Thanks for continuing to bang this drum for me, @DannyP, as I sometimes feel like I'm out here wearing animal furs and eating locusts, and sounding like a zealot regarding this topic. Perhaps someday someone will ask for my head on a platter, but until that day comes, I'm going to have to pipe up on threads like this one.

I'm not sure what it will take to get this out there so that people will listen, as there's a limited number of different ways to say it. I'm thinking of printing tee-shirts and giving them away, or getting the message tatooed on my forehead:

90% of "carb" problems are "spark" problems.

Everybody bags on Webers and Dellortos, blaming them for everything bad-- but it's really the spark that is 90+% of the "not quite right" problem. Electronically controlling spark in an engine isn't just low-hanging fruit-- it's fruit that is perfectly ripe, unblemished, and has fallen washed and sliced, directly on the plate. It's the single greatest advancement in engine operation in the last 50 years (and there have been some amazing advancements). It's having your cake and eating it too.

The CB Black Box is as simple as it's ever going to get. It can set it up for a perfect "all mechanical" (RPM only) spark curve, or allows vacuum advance with the kind of adjustability one can only dream of with springs and weights. Using one allows the timid or retro-purist to retain the 009, 009 clone, MagnaSpark (or whatever other distributor is back there).

It's $200, and an amazing bit of kit for the money. 

 

First, belated birthday wishes.

Then..."I'm going to have to pipe up on threads like this one."   LOL

Art

Mitch, thank you for what could be the real solution to a problem I've been trying to solve for over a year, hesitation when accelerating from a standing stop

We've tried every trick in the book that we could find to correct the problem.  Even got another Magnaspark II distributor to replace the one that came with the engine to see if the first one might be faulty; however, the new one did not come with that extra set of advance springs you described so I called David at CB Performance and he's sending me a complete spring kit today.  Cost: $5.00 plus postage.

Cliff 

I, for one, am doubly glad.

For one, I bought a MagnaSpark II last Spring for the same reason Mitch mentioned:  There were a Plethora of different Bosch distributors offered but no one hardly ever offered the springs or weights to allow you to make their advance curves different and, even more, hardly anyone anymore really knows the difference between a 010, an 012 or my personal favorite, the venerated 050, and what springs and weights to use for each.  Pat Downs did all of that research for us and gives us not only a disti that should be in the ballpark right out of the box, but it is then easily tailorable to get us to home plate.

For twooth, I looked in mine and had forgotten that the springs were right on top of everything once you pop the cap and rotor off, unlike the Bosch unit that puts the springs under everything else and is a minor PITA to service.  The MS II springs are SUPER easy to get to and I think 8 of the ten minutes Mitch quoted was just getting the cap off and back on while holding a flashlight in my teeth in a 30º garage.

Thanks for the tip, Mitch!

There are lots of ways to correct spark scatter, boys. I mean, sure, you could go with a "programmable" electronic ignition ("programming" in this case meaning "enter your desired advance numbers in a series of boxes according to RPM"). But where's the fun in that?

Truly, the most period correct method is to reengineer your distributor with the addition of "a miniature flywheel."  

 

Cliff Presley - Charlotte, NC posted:
 

Mitch, thank you for what could be the real solution to a problem I've been trying to solve for over a year, hesitation when accelerating from a standing stop

We've tried every trick in the book...so I called David at CB Performance and he's sending me a complete spring kit today...

 

Good luck, Cliff.

This is by no means a panacea and it will only help if an inappropriate advance curve is what's causing problems. It's very possible that changing the springs will make things worse - but then, it's easy enough to return to where you started out.

That said, it's a cheap and easy thing to try, so, again, good luck!

 

After installing one "blue" spring, I took Pearl out for a morning ride.  The thermometer outside of the garage said 34º and that always meant a lot of coughing and puking as it woke up in years past cuz it didn't like the cold.

Not this time....

Got in, turned the key, waited 10 seconds for the pump to fill the float bowls (it had been sitting for a month), pumped it 5 times and........

It started right up and idled really well.  Had to hit it with the pedal two more times to get it to smooth out and then let it idle in the driveway for a minute while the gas heater came up to speed and I took off - - - no coughing or puking, no bucking, no hesitation.  

Can this really be my car?   

Between all that terrific work by Dave at Blackline Racing on my Carbs and this little tweak to the advance, it's running eye-poppingly well.

Thanks, Dr. Mitch!

Hello Gordon & Mitch,

Wow!  Having tried to solve a similar problem for the last year, after reading the positive experience both of you had with one of those "blue" springs in your Magnaspark, I am really excited about getting one for mine. 

Just call me a happy little boy who can hardly contain himself.

          1. Happy little boy

Hopefully, the new set David is sending will arrive early next week.

Cliff 

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