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Mon Oct 19, 2015 3:27 pm

I've never heard of them, but I have an ignition from an engine that I bought. It sat out in the weather for 10 years or so, so the cap and wires are pretty weathered. I put some stock wires on it and it works, but I suspect they had 8.5mm wires for a reason.

Any pros or cons, or personal experience? The only website I can find for them is really unhelpful. I sent them an email as well, waiting to hear back.

Mon Oct 19, 2015 4:34 pm

There are a few people that swear by the Jacobs ignition systems. Most people view them as just another waste of money on a item that will not make any more power then a Bosch 009 and blue coil.

Mon Oct 19, 2015 6:27 pm

Yuo should PM Scott Novak, he's the local expert on Jacobs.

http://www.thesamba.com/vw/forum/privmsg.php?mode=post&u=32243

Mon Oct 19, 2015 8:57 pm

I agree Scott is the expert.

I am a user for 20 years, I bought a Bugpak made just for bugs. My engine ignition looks stock but the coil is only used as a trigger for the Bugpak which is mounted in the luggage area behind the rear seat. The heavy ignition wire goes through the firewall to the center of the Distributor. If you lock at my ratty engine, cylinder # 2 ignition wire with it hold down. Between the wire and the gas hose is a black wire. It comes from the center of the coil and bolted to the upper cylinder tin which is Ground. The coils blast goes directly to ground.. The instructions said just use standard style plugs to handle the spark and open them up from .024 to .050. Monster spark!!! I would get a shock from a stock ignition, ok it hurt. THis baby, feels like you were hit with a base ball bat. Made a major difference in power seeing I could now increase my main jet size to a larger size. Then when I went to a Mallory Unilite from the 009, even a more power and better running. For a Basic Daily driving 914 engine it has been a vast improvement. Especially in sub zero temps when starting. There may be better units for racing but for me it has been great.

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Mon Oct 19, 2015 10:13 pm

Which model Jacobs ignition are you using?

Is it all in one like the Omni-Pak pictured above.

Or does it have a separate ignition coil and ignition box?

The Omni-Pak is about the only Jacobs ignition that doesn't multi-spark. But it still packs quite a whallop. You'll know what I mean if you ever get shocked by one. It's literally power you can feel. I've also measured the output under load conditions and it makes a Bosch ignition pale by comparison.

With a Jacobs ignition you will want to use a larger spark plug gaps for improved performance.

Bug Pak was just the name they gave the kit. The same Omni-Pak pictured above is also used for 8-Cylinder Detroit iron.

There are Omni-Paks that will trigger directly from points without the original ignition coil connected.

A Jacobs ignition will usually fire the spark plugs in a flooded engine with wet fouled spark plugs, whereas the stock Bosch ignition can't start the engine.

And yes, there IS a good reason for using 8.5 mm ignition wire with a Jacobs ignition system.

Scott Novak

Tue Oct 20, 2015 4:32 am

The lowest voltage I've seen quoted for any of the newer aftermarket CD ignitions is 450V to the coil primary. I believe Jacobs advertised over 500V but I don't know about the Omni-Pak. With CDI, you do not need excessively high voltages, nor is it desirable. With CDI you can run spark plugs completely immersed in water with a primary voltage less than 300V and a stock coil. The available voltage is only a small part of what makes CDI better in most circumstances. The secret is power delivery that allows wider spark gaps with less total available voltage than a stock system with a high turns ratio coil.
With any ignition system, you can't completely control the secondary voltage with the plug gap, but with inductive systems you can for all intents and purposes. With CDI, the primary voltage will be whatever the CDI puts out based on the voltage the discharge capacitor was charged to prior to firing, so if that voltage is too high it can stress the primary windings. On the secondary side of the coil, excessive voltage does two things. It makes the voltage rate of rise much faster which also stresses insulation and increases corona losses, but it also gives a higher voltage overshoot before spark breakdown, so the spark plug gap has less effect in controlling the overall peak voltage experienced by the secondary winding insulation and also the ignition wires. The high available voltage allows opening up the plug gaps slightly more, but at the detriment of secondary side insulation including caps and rotors. There are diminishing returns in opening up the plug gaps. At some point, even if there is enough voltage to get the job done, no benefit is realized by opening the gaps further.
Most racing type CDI's, especially those that multi-spark, have small storage capacitors charged to very high voltage to get the required energy storage. The other way to do it, that actually works better, is to use a larger capacitor, charged to a more reasonable voltage. Even if the milli-joule storage is the same, a larger capacitor has more coulombic charge than a smaller capacitor charged to a higher voltage. The result is a spark that forms just as readily because it takes current as well as voltage to make a spark, and the higher coulombic charge improves current delivery.
Even GM back in the late sixties knew when using CDI, that voltage had to be kept within reasonable limits with distributor type ignition systems. They chose 300V. They had a poor, unreliable design that they abandoned in favour of HEI, but that's how they solved their reliability problem with CDI. The models I make, put out up to 340V while on starter motor which drops immediately to less than 300V once the engine is running. Voltage rise time is controlled two ways. First, the peak voltage is not silly high which reduces the steepness of the voltage slope, and secondly, if you use a standard canister style coil, that also keeps the voltage rate of rise about the same as using a transistor to switch the coil. Even with the voltage rate of rise very similar to that of a transistor switch using the same coil, the ability to overcome fouling is a minimum of ten times better with this CDI. Because, it is power delivery capability that makes the difference in beating fouling (or letting the engine run with the spark plug insulators under water!) Fred

Scott Novak wrote: Which model Jacobs ignition are you using?

Is it all in one like the Omni-Pak pictured above.

Or does it have a separate ignition coil and ignition box?

The Omni-Pak is about the only Jacobs ignition that doesn't multi-spark. But it still packs quite a whallop. You'll know what I mean if you ever get shocked by one. It's literally power you can feel. I've also measured the output under load conditions and it makes a Bosch ignition pale by comparison.

With a Jacobs ignition you will want to use a larger spark plug gaps for improved performance.

Bug Pak was just the name they gave the kit. The same Omni-Pak pictured above is also used for 8-Cylinder Detroit iron.

There are Omni-Paks that will trigger directly from points without the original ignition coil connected.

A Jacobs ignition will usually fire the spark plugs in a flooded engine with wet fouled spark plugs, whereas the stock Bosch ignition can't start the engine.

And yes, there IS a good reason for using 8.5 mm ignition wire with a Jacobs ignition system.

Scott Novak

Tue Oct 20, 2015 6:21 am

Fred you said " The secret is power delivery that allows wider spark gaps with less total available voltage than a stock system with a high turns ratio coil" . With out getting technical that is exactly what it does. When I called the Jacobs Tech Support asking about if I could use a special plug for it to work better, they said " Get a good stock plug, platinum, or triple electrode, etc. All you want is a heavy hunk of metal between the electrode and ground to carry a spark. He also explained about as you said diminishing returns of opening the gap too much. He gave am a formulator, as to how many thousands to open the gap, I started a .040 and now keep it at .050 for the last 20 years. Plugs look perfect after every tune up.

The bottom line is simple it gives a Massive Spark that will start the car under almost any conditions. .

Tue Oct 20, 2015 6:38 am

nextgen wrote: Fred you said " The secret is power delivery that allows wider spark gaps with less total available voltage than a stock system with a high turns ratio coil" . With out getting technical that is exactly what it does. When I called the Jacobs Tech Support asking about if I could use a special plug for it to work better, they said " Get a good stock plug, platinum, or triple electrode, etc. All you want is a heavy hunk of metal between the electrode and ground to carry a spark. He also explained about as you said diminishing returns of opening the gap too much. He gave am a formulator, as to how many thousands to open the gap, I started a .040 and now keep it at .050 for the last 20 years. Plugs look perfect after every tune up.

The bottom line is simple it gives a Massive Spark that will start the car under almost any conditions. .

To add......there are pluses and minus's to both CD and inductive. Whether the6 are minor or major depends on what your are doing with it. For high compression and high rpm......a high turn inductive system generally produces a more reliable large spark.

Ray

Tue Oct 20, 2015 6:52 am

But don't forget that there are many variations of CDI. An inductive spark is an inductive spark, period, but a CD spark can be multi-phase, single phase, long duration or short duration. Mine is long duration (useful duration) and multiphase. Fred

raygreenwood wrote: nextgen wrote: Fred you said " The secret is power delivery that allows wider spark gaps with less total available voltage than a stock system with a high turns ratio coil" . With out getting technical that is exactly what it does. When I called the Jacobs Tech Support asking about if I could use a special plug for it to work better, they said " Get a good stock plug, platinum, or triple electrode, etc. All you want is a heavy hunk of metal between the electrode and ground to carry a spark. He also explained about as you said diminishing returns of opening the gap too much. He gave am a formulator, as to how many thousands to open the gap, I started a .040 and now keep it at .050 for the last 20 years. Plugs look perfect after every tune up.

The bottom line is simple it gives a Massive Spark that will start the car under almost any conditions. .

To add......there are pluses and minus's to both CD and inductive. Whether the6 are minor or major depends on what your are doing with it. For high compression and high rpm......a high turn inductive system generally produces a more reliable large spark.

Ray

Tue Oct 20, 2015 7:55 am

Is Jacobs still in buisness?

Dan

Tue Oct 20, 2015 8:43 am

Well, I probably should have been better prepared to respond. I don't know what model it is, the distributor kind of looks like an 009, doesn't look trick or anything, but it's obviously different when you pull the cap. And the coil is a pretty large and heavy piece mounted on the firewall with a sheet aluminum cover, not the fancy finned extrusion thing like in previous pics.

I meant to get the numbers off the dist housing last night but got carried away pulling the beam out of the car instead.

Tue Oct 20, 2015 10:20 am

Jacobs was purchased by Mr. Gasket. Some Jacobs products are using the Malloy and Accel names.

Scott Novak

Tue Oct 20, 2015 10:25 am

lol.. I've been shocked by the stock ignition and I sure as hell can feel THAT!

Tue Oct 20, 2015 10:34 am

Dauz wrote: lol.. I've been shocked by the stock ignition and I sure as hell can feel THAT!

You haven't really been shocked until you have been bitten by a Jacobs multi-sparking ignition.

Scott Novak

Tue Oct 20, 2015 12:13 pm

If I had problem with my bug's stock ignition I would grab each wire to see if I was getting a spark while it was running.

Grabbing the Jacobs wires was not planned and will not happen again. Well If I can help it.

Tue Oct 20, 2015 1:18 pm

The Omni-Pak, Omni-Torquer and Omni-Magnum are all inductive switchers.

The Omni pak only produces a single spark. The Omni-Torquer and Omni-Magnum are multi-sparking.

The switching semiconductors in the Omni-torquer and Omni-Magnum are not directly connected to the outer case and as a result I believe they can overheat and fail. This is why I don't recommend the Omni-torquer and Omni-Magnum.

Jacobs did vary the capacitance of the storage capacitor in various models. The Jacobs CDIs don't all spark the same.

Especially in a VW using a small distributor cap I recommend lower turns ratio ignition coils.

Fred,

It would be interesting to see how the various CDIs stack up to yours under actual load.

Scott Novak

Tue Oct 20, 2015 2:38 pm

Scott,
I did not realize that most of the Jacobs systems were inductive transistor switch types. If you read Dr. Jacobs book you would gather that he was slanted towards CD ignitions. The patents of his that I looked at were all CD ignition.
The only back to back testing that has been done so far was by a member of the Morgan club on his Rover powered Plus 8. He replaced a failing MSD with one of my prototypes and did not notice any difference between it and the MSD. Both systems improved the engine in the same ways. He runs a 40 thou spark gap and the engine is mostly stock. Using a pertronix unit to trigger the prototype he did back to back runs on a proper dyno and came up with an overall improvement in HP of 3 to 4% for most of the rpm range. Unfortunately this wasn't compared to MSD, only to Pertronix, which as we know is rather weak. What I am building is a slightly more powerful, and slightly longer duration version of the Hyland ignition built from 1963 to 1965. Lots of testing was done during those years with the comparisons made between transistor switch units of the time (which weren't nearly as good as now, so not quite a fair comparison) and points ignition. There were no other CD ignitions to compare it to other than the Tung Sol EI-4 and later the Delta Mark 10 thunderbolt, and those comparisons weren't made at the time. The testing then with dynamometers showed improvements that varied from the low value I quoted for the recent dyno test, to much greater gains depending on the engine and modifications made to it. Performance engines had the most gains, but not always. Lots of Hyland units went racing back then.
My resources to dynos and various engines is limited, but one thing I am acutely aware of is that there are huge differences in the design of CD ignitions. Motorcycle CD ignitions are quite different from automotive CD ignitions for practical reasons and tend to have short duration sparks. Multi-spark CDs for cars tend to have short duration sparks as did many of the older single spark designs for cars. Mostly it was done to keep the capacitor small so that the power supply could keep the capacitor sufficiently charged at high rpm. That design compromise usually meant that the unit put out too much voltage at low rpm (Bosch 8 pin units for example). Some are current hogs because of poor design. Recently I bought an NOS Delta Tiger SST. This was the first of the Tiger series and one of the designs that infringed most closely on the Winterburn patent. However it's very badly made being a current hog with a short spark duration. You could install it on an old car and the old car would run better most of the time, until the unit failed that is. I could go on and on, but I'd better not! Fred

Scott Novak wrote: The Omni-Pak, Omni-Torquer and Omni-Magnum are all inductive switchers.

The Omni pak only produces a single spark. The Omni-Torquer and Omni-Magnum are multi-sparking.

The switching semiconductors in the Omni-torquer and Omni-Magnum are not directly connected to the outer case and as a result I believe they can overheat and fail. This is why I don't recommend the Omni-torquer and Omni-Magnum.

Jacobs did vary the capacitance of the storage capacitor in various models. The Jacobs CDIs don't all spark the same.

Especially in a VW using a small distributor cap I recommend lower turns ratio ignition coils.

Fred,

It would be interesting to see how the various CDIs stack up to yours under actual load.

Scott Novak

Tue Oct 20, 2015 5:12 pm

Jacobs first ignition systems were in fact inductive switchers. Later on he started making CDIs. Both types were sold by Jacobs.

I talked with one engineer that said the main difference between the Jacobs Pro Street, Off Road and RV CDIs was the size of the storage capacitor.

Scott Novak

Tue Oct 20, 2015 5:33 pm

Most small engine CDs are designed to work with very little energy input especially if there is no battery. Imagine how small the storage capacitor needs to be on a motorcycle with a kick starter. One kick needs to be able to charge the storage capacitor to a sufficient voltage to create a spark. The ignition coil needs to be efficient as well to keep energy losses to a minimum. That means a low inductance coil which shortens the duration even further. They work well for what they were intended for, but obviously a good CD ignition for a car needs to be designed differently. Oddly, it was the more complex application for cars, not small engines where CD ignition was first put into practice. The 1906 Ford Model K actually. Fred
Scott Novak wrote: Jacobs first ignition systems were in fact inductive switchers. Later on he started making CDIs. Both types were sold by Jacobs.

I talked with one engineer that said the main difference between the Jacobs Pro Street, Off Road and RV CDIs was the size of the storage capacitor.

Scott Novak

Tue Oct 20, 2015 6:26 pm

Hello Fred, I have been reading a lot of your posts today and have learned a lot about ignitions from many posts in new and old threads. I will say thanks for the knowlege.

I am working on a 6 volt hipo car right now and plan to sell it soon so investing in one of your units is not going to happen for this car anyway but maybe a 12v car in the future.

Do you know if the transistor switcher msd 5 has the one volt semi conductor drop like most switchers or maybe I should just use the stock bosch ignition.

I too have designed bi-polar circuits for slot car controllers and had to deal with the drop.

I have found that MSD tech line guy are not very good.

Dan