Tiger CDI and ignition coil

You do need the ballast if using points.

For far, far more than you wanted to know about coils and hi-energy ignition, read thru this tome:

(though it may not directly address your question) Jim

Thanks for the reply. I will install the coil with the ballast resistor, although I understand that with the CDI module the points only trigger the coil and do not carry current. Or rather, only an insignificant current.

James

The stock Bosch coils for old air-cooled VW=92s has a built in ballast resistor. Are you saying that you have an aftermarket coil that uses a separate ballast resistor?

If so then, yes use it. Sorry, didn=92t mean to advertise.

I have a 1973 VW Beetle with: Tiger CDI and

Jacob=92s Plug wires

NGK B5HS or Bosch W8AC plugs gapped to .038 IN. The instructions say .

041 IN but I allow a margin for error. stock and MILD high performance engines. We have found NGK isbetter than Bosch, and are equipped on the NEW VW engines in Mexico!Price is for a set of 4 plugs. SVDA distributor High Energy Distributor Magnition cap from CB Performance Modified rotor from aircooled.net

I like these add-ons. It works for me!

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Here are some good links that include install instructions and a paragraph from Bob Hoover from one of these links:

Engine Compartment Wiring, Stock (Without CDI or CompuFire)

A Bob Hoover Sermonette on CDI Systems (Used with permission.) Two types of CDI units are offered -- a points-triggered CDI module and an optically-triggered CDI module.

The stock points work okay for triggering the unit... sorta :-) The points never wear out since the triggering signal is only about two hundred and fifty milliamps (a quarter of an amp) as compared to 10 or

11 amps in the stock system. But the rubbing block wears down and you have to regap the points every 25000 miles or so. And as the miles build up the spring on the points weakens and you start to see points bounce, even at fairly low speeds. But points are inexpensive, robust and universally available making their use practical. I started using CDI modules in the 1960's and used the stock points for triggering until something better came along.

As a final note, a lotta guys go to a CDI module because they are having ignition problems and sure enough, the problem goes away once the unit is installed. You'll hear this same story from guys who merely replace their points with a Pertronix or other brand of electronic switch. But the odds are, the problem would have gone away with a good tune-up or rebuilding the distributor, which needs its seals replaced about every 50000 to 70000 miles. If your distributor needs an overhaul, the mainshaft will be loose and that looseness will cause excessive 'hunting' -- the spark won't always occur at the proper time. A CDI module will trigger reliably with a point gap that's too small to measure (!), meaning it will even trigger reliably (although not accurately) with a distributor that is virtually worn out. By the same token, replacing the points with some form of magnetic triggering often masks that wear. Your distributor is still worn out and should be overhauled or replaced but the 'hunting' will have vanished -- right up until the mainshaft binds or the dog gear breaks off or some other catastropic failure occurs. There's no such thing as a free lunch J :) ~~~

Install a rotor that has been modified for high-output ignition systems (see following note). Note: John Connolly (Aircooled.Net) says "If you have a high-output ignition (e.g., CDI), here's a tip. Bosch rotors have a resistor between the middle and end, under the epoxy. High output ignitions WILL burn this out, resulting in you tearing your hair out trying to find the cause of the misfire. Dig it out, and then braze a piece of brass in place of the resistor. Fresh epoxy will finish the job nicely. NO MORE MISS." Modified rotors for high-energy systems are available from Aircooled.Net. ~~~

This is from the link above:

Ignition Rotor Price: $ Varies according to options Part #: IGR0002 Genuine Bosch or OEM Rotors. NEVER use aftermarket for ignition parts! Rev control rotors CAN USE the late beetle rotor if you don't mind losing the RPM limiter. Also, if you have a high output ignition, here's a tip. Bosch rotors have a resistor between the middle and end, under the Epoxy. High output igntions WILL burn this out, resulting in you tearing your hair out trying to find the cause of the misfire. Dig it out, and then braze a piece of brass in place of the resistor. Fresh Epoxy will finish the job nicely. NO MORE MISS.

Modified Rotor, SVDA, 009, and 69+ Stock Distributors $18.00 This modified rotor is used on high energy ignition systems. Fits 69' and newer stock distributors, our SVDA, and 009s. The stock rotor has a resistor in it which will BURN UP if used with our CDI, MSD, or Jacob's ignitions. You can do it yourself, but we have these already modified for your convenience. The epoxy is ground out, and the resistor is replaced with solid wire to handle the extra ignition power (the resistor will eventually burn out). The wire is re-covered with epoxy again, and ready to go.

Add a CDI to your Igniti> =A0Several years ago I installed a Tiger CDI module and on the

My impression of ignition coils is that there are ones that dont have a ballast resistor, internal or external and there are ones that do have external ones. The coils that use an external resistor are really coils rated at about 9 volts on the primary.. The 12 volts fed to the starter from the ig switch also goes straight to the coil, the idea being because the engine is being cranked over the battery voltage falls to about 9 volts and you get full output from the 9 volt coil. When the engine starts the start signal from the starter motor drops and 12 volts is fed via the ballast resistor to the coil. The resistor develops about 3 volts across it to stop the 12 volts overheating the 9 volt coil. On that basis I would not feed the CDI to a Coil designed for a ballast resistor. I suspect the HT voltage to plugs will be too high. Had a CDI on my trusty 1300 many years ago,. whenever there was fog the engine bay lit up like an amusement park. Occasionally the thyristor would blow , usually at most inopportune time. Gone back to points/coil/plugs. John

• to use a stock coil with a ballast resistor.

• not to use a high output coil.

• to use stock spark plugs. Do not use the fancy triple electrode or Platinum plugs.

• to gap the plugs to .040 -- .041 inch gap.

• to use special 8.5mm HEI spark plug and coil wires.

I think I will remove my CDI. I got over 7 years of use with it. I think it will run just as well with the stock distributor, Pertronix drop in ignition, and stock coil. If I drove quite a bit on he highway, I might keep the CDI. That's where you get the extra mpg from the CDI, not while driving around town. It just seems like one more thing to go wrong. Have a good one!

A stock coil has a internal resistor, easy to measure with a multimeter. Primary resistance should read 3 - 4 Ohm.

You can use any coil you want with the same as stock coil resistance, again primary resistance should read 3 - 4 Ohm.

Nothing wrong with either, although I would stay away from triple electrode plugs as the two extra electrodes shield flame propagation in the combustion chamber. Platinum's are recommended for longer service life, as is Silver or Iridium. The only argument against these plugs are price.

Correct.

No need for 'special' coil wires as long as the ones you use can take the extra voltage, I have used cheap aftermarket 'silicone' wires for years without any problems what so ever. Do however remember to use a rotor without the built in resistor, as this can burn out and lead to misfires. You can modify your own or buy a modified one from

Why? Have I missed a part of the thread?

It will not start as easy, and it will not run as clean whilst only partially warmed up, this is where you save gas.

On the contrary, with highway use you a have a fairly steady load, little or nothing to be gained from the CDI. Around town you use the full register of the carb which is never perfect when it comes to mixture, the CDI will help you to get a more complete burn during varying rpm's and load/register of the carb.

Not sure what CDI you use, most have an exclude mode where you eliminate the CDI function either via a switch or by turning an electrical connector/plug around(Tiger CDI has this function).

I have the Tiger CDI John C. of aircoolednet was selling back in 2000 or so. It has a plug so I can eliminate the CDI function by turning it. You can choose points/Pertronix or CDI.

If I turn the plug to bypass the CDI and have it run on points/ Pertronix, will it run with the plugs gaped to .040inch?

After reading your reply I think I will keep the CDI. Besides, I recently bought a new HEI distributor cap for my SVDA distributor to use with the CDI.

Once I removed the cover from the CDI and applied some bronze/orange Permatex rtv sealant to keep the moisture out. Is that ok or should I have left the gap to let some of the heat out?

Will the CDI make the engine run hotter?

extra voltage, I have used cheap aftermarket 'silicone' wires for years wi= thout any problems what so ever.

can burn out and lead to misfires. You can modify your own or buy a modifi= ed one fromwww.Aircooled.net

ally warmed up, this is where you save gas.

or nothing to be gained from the CDI.

when it comes to mixture, the CDI will help you to get a more complete burn= during varying rpm's and load/register of the carb.

the CDI function either via a switch or by turning an electrical connector/= plug around(Tiger CDI has this function).

The very same I used with a Pertronix module, great unit.

Yup.

Yes it will run.

To be honest I cannot remember the exact dimensions/construction of the unit, so I cannot answer that. I believe they also sold a Marine unit which looked the same, so a guess would be you are ok.

No.

J.