Adaptive Spark Ignition System & Spark Plug Gap (Page 1 of 2)

It's good information Scott. Even modern high-energy adaptive ignition systems still misfire some. If you tie VAG-COM into the EMU of a new model VW it can read the EMU's evaluation of misfires, and it will always note some small %, but only raises a fault code when the % increases above a certain amount.
I've experimented with add-on ignition systems & different plugs for 40 years, and with one exception could never measure a quantitative improvement over a well-maintained stock system, in spite of the theories. I used to record mileage in a log every fill up and track mileage carefully, which should correlate to combustion efficiency, and generally found no significant difference. But I drive for transportation rather than performance, so that may keep the demands on the ignition system low, and the difference for someone else might be more. Most of my experimenting was in the 70s & 80s with various CD & trigger systems, so the technology may have improved. These days cars come with better systems anyway, and many of us with old VWs like to keep them simple vintage stock, and avoid adding complexity.
However, most of the improved systems remove variability so the spark doesn't degrade between tune-ups, or extend tune-up intervals - and that can make a difference for anyone.
The hard part is making objective, quantitative measurements to substantiate results, because most people will "feel" an improvement with any change they make, even if actual measurements show it reduced performance. (That's why snake oil continues to sell...)
The one real difference I found was on a 97 Eurovan Camper, where a change to Platinum +4 plugs consistently improved mileage almost 2 mpg. I changed back to new stock plugs for a few months and mileage went back, changed back and regained the mileage - so on this VR6 engine, the way I drive (with the 6,000 lb beast) it made a real difference.

So you're a salesman for Jacobs then right?  Regardless of the method, the results can be obtained from any number of other options.  As Tom pointed out, a stock setup in perfect condition will peform almost identically to all the fancy stuff out there.  The catch is that with a kettering setup you have to really be on top of your tuneups.  Now if we're talking non-stock applications, a good CDI will perform as well as any other good aftermarket ignition, Jacobs or otherwise.
As for the limitations of the stock size cap, it's about .045" at around 8.0:1 CR static.  However if you vent the cap it'll go quite a bit higher.  --Ryan

Ryan,

I'm not a salesman for Jacobs, although I have bought and sold used Jacobs igntion systems, and have kept the cleanest units for my own use.  I've also suggested to people not to buy the Jacobs ignitions that I sell on ebay, as I receive consistantly higher prices than most people do.

Have you ever actually USED a Jacobs ignition system?

I don't put alot of stock in tests that Hot VWs has run.

Some products DO work as well as they claim.  I can point to Redline Polyolester synthetic lubricant for one.

There's no reason in the world to assume that Weber made their carbs are well as they could.  There are any number of modifications that can be done to improve flow through a Weber, so there is no reason to think that Empi couldn't improve upon it.  Although a lot of the new EMPI stuff is crap.

The Kettering system that VW used simply does not have enough output to fires significantly wider spark plug gaps.  If you can't open the spark plug gap wide enough, you'll have more ignition lag, during which the optimum timing varies and a because of that your timing will not be close to optimum all of the time.

You can only optimize a Kettering ignition system to work well over a limited RPM and load range.

I've used regular CD systems and they simply don't work as well as the Jacobs adaptive spark ignition system.

Also note that Jacobs was only claiming a 7% horsespower increase which is in line with their claim that many cars misfire more than 8% of the time under certain conditions such as full throttle acceleration.

And yes the stock small Bosch distributor cap is a big limiter of performance.  That's why I'm using a Mallory distributor and will be adapting it for an even larger distirbutor cap.  Detroit went to much larger distributor caps for a good reason.

Scott Novak

Few more things, then I'm done.  Seriously, are you quoting this stuff right out of the book from Jacobs?  It's about the only place I've ever seen this stuff mentioned.  Funny how it supports his own products.
Secondly, you don't run at Stoic because you make more power with more fuel.  You should only get close under low load or idle conditions.  Not to mention, this is an aircooled engine, whether you wish to believe this or not, fuel helps cool the combustion chambers.  Oh, and there are people out there running on the friggin edge of stoic with a STOCK setup, well actually with a points replacement module.  But then again it's the points/condensor setup that are the weakest link anyways, you might want to mention that for everyone else.
Finally, mags are weak egh?  Do you have any idea how much power is put out by a mag used in top fuel?  You shouldn't blanket statement everything.
I think you'd get a better response if you only said what you have personally learned yourself.  If you can't afford dyno time, then there's no way in hell you've done any tests to back the quantatative data you've spewed.  If it runs better, just say so.  But expect people to say the same about all the other good systems out there too.  Seriously is it too much to ask for you to back up your statements with real facts and not book facts?  --Ryan

Nick,

Read the topic:

"Reccomended ignition system? by elliot"

The Omni-Pak is a high output ignition coil WITH the electronic ignition built inside.  It replaces your coil and will fit in the stock coil location.

The 6 wire Omni-Pak will work with any of the electronic trigger units that I'm aware of, including Pertronix, and Compufire.

You need to replace carbon core spark plug wires if you are using them.
I'd recommend better spark plug wires even if the rest of the system was stock.

You need a distributor rotor without an internal resistor.

Standard non-resistor copper core spark plugs work best.  I like Champion L87-YC.

A Mallory vacuum/centrifugal advance distributor has a larger distributor cap and would be great, but it's usually very pricey and it takes time to setup properly.

Scott Novak