I went with the Hot Spark that replaces the condenser and the points in the disty. After 38000 miles.... maybe 10000 with a new voltage regulator I determined that my module was seriously acting up. That's all in another thread.

This thread is for helping me make sure I don't have problems down the road, so chime in if you can help.

The manufacturer recommends, actually requires that you only put 13.7 volts at any RPM into their module. So I tested it after I put my spare module on the car.
Click to view attachment
My 75 L-Jet 1911 cc engine idles perfectly at 950. 1 VOM lead on the coil + the other on ground.

Results of the test are as follows:

voltage at Idle.... 13.9 -14.2 fail
voltage at 4000 rpm... 13.6 - 13.9 fail

Hot Spark says to put a 1.4 ohm Ballast Resistor between the module and coil +... Moved the VOM lead to the exit end of the resistor.
Idle....13.9 - 14.2 fail
4000...13.5 - 13.68 pass

Tried a 5 ohm Ballast Resistor
Idle...13.95 - 14.02 fail
4000...13.57 - 13.61 pass

5 ohm BR and the headlights are ON
Idle...12.28 - 12.32 pass
4000... 13.29 - 13.31 pass

Now I can't drive around with my headlights on all the time. 2ndly I would say that the % of idle time is way less than the 3000 to 4000 rpm driving time.

What are your thoughts? Why do I see no change at idle? What else is out there to use instead. This module is only $35 so I figured it was cheap technology. It was simple and maintenance free. Bolt it on and plug it in.

ive had the same hot spark module for past 5 years, no issue.

ive not had a problem but I didn't put a resistor in there either - but I do have their coil too - this will not matter once I get the I 123 distributor on the group buy!

Good to know someone has used their product with success. I assume you never did the tests? How many miles you figure on yours?

I recently bought their coil too. So the recent tests using the resistors are with their coil. the 2ndry R was 7000 ohms, as they suggested. primary was 3.3 ohms, also as they suggested. My previous coil was 9400 & 3.6, respectively. I would still consider my original as GOOD, passing all their tests.

I just don't understand why the resistor has no effect on the voltage while at idle.

I have an original SVDA type but its the Bosch unit,have hotspark on it but not yet installed ,I researched a fair amount before buying appears they are fine,however they haven't sold in the numbers that Pertronix have so documented failure would be less I suspect.
My unit was UK sourced and came with a Lucas gold 3.0 ohms coil but I believe there was mention of the Bosch blue coil working also.
Never saw any mention in the instructions of a resistor,maybe that's for use with a stock coil ?,truly I really don't know.

The operating spec from Hot Spark is curious to me - as the voltage regulator spec for most of our cars is rated at a nominal 14V (i.e. over the suggested 13.7V maximum!).

If I was trying this set up, I'd be wiring in a 1N4001 diode in series with the Hot Spark feed (instead of a ballast resistor); this will drop around 0.5V - 1V from the regulated voltage which should keep the Hot Spark in spec...?

You may need to exercise some soldering skills, and the diode should be widely available (eg RadioShack..)

Old thread - just seeing this now as I am doing research on a voltage regulator replacement.

Has your situation been resolved?

I've had the Hot-Spark unit in my 914 since 2011 or so and over 30k of driving and have never had a problem with it even though my charging system has been sketchy at best the entire time.

In helping others with their Ljet issues, I have found a few hot spark modules acting goofy. Currently, the hotspark module in my 914 is acting very goofy and is misfiring at idle (had it for over 5 years). I was a huge proponent for this 30 dollar module, but now I'm steering folks away and advising the 123 dizzy instead.

When it gets to the top of the list, I will get the 123 dizzy, it looks and sounds like a real nice upgrade, but 5 years out of a $30 to $50 part is a bargain. I haven't even had the cap off the distributor or adjusted the timing after all the miles and time!

I have not tested or changed anything since October. Have made a few trips and drive to work on most dry days. I still would like to try RETRO RACER's idea, but just have not gotten to it.

I keep a spare Hot Spark in the trunk for the next failure and then I guess it will be back to the points and condenser or to the new disty. Depends on how I feel at the time.

Did you see the post I did with Tim's help using the timing light? It really shows the "cut-out" across all 4 cylinders.