Crazy TI thing
Thread Starter
Pro
Joined: May 2011
Posts: 722
Likes: 58
From: Karlsruhe (Germany)
Crazy TI thing
Yesterday I helped a friend of mine with his ´68 Tripower.
The engine had slightly missfires and interruptions when cruising and under light acceleration.
After rebuilding carbs, checking the complete TI-harness measuring all voltages, testing 3 kinds of spark plugs, testing 3 different coils, replacing plugwires and rebuild the distributor (advance limiting bushing was worn out), it turned out that the TI-module was somehow defective. Replaced with a new one and problems are gone. Well this all took 2 days of work, and is just for your information what could be a reason for such a problem.
What I wanted to discuss was the following:
When we had rebuilt the distributor and put into place we started the engine and it idled fine.
The I remembered, that I had not connected the tachdrive and the magnetic pickup wire. It was hanging down behind the engine, while it was still happy idling. Had also connected the strobe lamp and it worked nice too.
Well we decided to shut it down immediately.
This is absolutely crazy, isn´t it?
Sure, the TI Module had a defect, but I just can´t explain what made it firing with a perfect timing.
Or could it be it was firing constantly all the time, actuated by voltage ripple from the alternator (what I could imagine), and the distributor finger and cap design made it just happen that it was not too advanced or too retarded.
The engine had slightly missfires and interruptions when cruising and under light acceleration.
After rebuilding carbs, checking the complete TI-harness measuring all voltages, testing 3 kinds of spark plugs, testing 3 different coils, replacing plugwires and rebuild the distributor (advance limiting bushing was worn out), it turned out that the TI-module was somehow defective. Replaced with a new one and problems are gone. Well this all took 2 days of work, and is just for your information what could be a reason for such a problem.
What I wanted to discuss was the following:
When we had rebuilt the distributor and put into place we started the engine and it idled fine.
The I remembered, that I had not connected the tachdrive and the magnetic pickup wire. It was hanging down behind the engine, while it was still happy idling. Had also connected the strobe lamp and it worked nice too.
Well we decided to shut it down immediately.
This is absolutely crazy, isn´t it?
Sure, the TI Module had a defect, but I just can´t explain what made it firing with a perfect timing.
Or could it be it was firing constantly all the time, actuated by voltage ripple from the alternator (what I could imagine), and the distributor finger and cap design made it just happen that it was not too advanced or too retarded.
Last edited by zuendler; Apr 10, 2015 at 04:19 AM.
Race Director
Joined: May 2006
Posts: 18,665
Likes: 2,564
based on this article you have two transistors in the amp, without the triggering transistor getting a signal the switching transistor would be on all the time meaning the primary circuit would constantly have power inducing power into the secondary circuit of the coil but at a reduced voltage. I could be wrong on this assumption.
http://www.tispecialty.com/articles/article1.htm
http://www.tispecialty.com/articles/article1.htm
Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 38
From: Fremont CA
based on this article you have two transistors in the amp, without the triggering transistor getting a signal the switching transistor would be on all the time meaning the primary circuit would constantly have power inducing power into the secondary circuit of the coil but at a reduced voltage. I could be wrong on this assumption.
http://www.tispecialty.com/articles/article1.htm
http://www.tispecialty.com/articles/article1.htm
If your have a K-66 equipped car, I highly recommend carrying a spare amplifier board with you if your driving it somewhere further than you want to walk.......
