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Transistor igniton issues.


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Lately has been a lot to talk about Pertronix ignitions. Personally like them as long as have 8mm plug and coil wires and use their coil.

 

OTOH if you have a factory tachometer then there may be an issue.

 

Back in the day I converted A Lot of GM passive tachs from the 60's to transistor to work with transistor ignitions. Cars that had the Delcotronic option received a different tach module when installed (dash looked the same but circuit was different).

 

In the 70s many were changed to transistor circuits. I used a lot of transistor circuits for Vegas (little ceramic disk) to convert, just had to change one capacitor.

 

Pretty sure the rarest Corvette distributor was  the 1111063/1111070 (et. subs) FI and tach drive with electronic ignition (no points). Fakes abound & many were converted to points. Look for both mag impulse coil AND dual mechanical drives (FI and Tach).

 

ps Delcotronic was 62-66, 67 was replaced by a CD ignition.

 

 

 

 

magimp.jpg

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Pretty sure the CD wasn't until '67 so a '66 427/425 wouldabin a Delcotronic ignition (if factory). It would have come with the transistor tach.

 

Delcotronic ignition (distributer, coil, amplifier, wiring) would not drive the standard passive (two wire) tachometer.

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1 hour ago, padgett said:

Pretty sure the CD wasn't until '67 so a '66 427/425 wouldabin a Delcotronic ignition (if factory). It would have come with the transistor tach.

 

Delcotronic ignition (distributer, coil, amplifier, wiring) would not drive the standard passive (two wire) tachometer.

That's what I had. Here's a list of tachs available in '66 Chevrolet full size.

6412548 -6000 rpm, 5k red line, used with 283/195hp, 283/220hp, 327/275hp, 396/325hp

6412571 -6000 rpm, 5k red line, used with 396/325hp equipped with RPO K66 Transistor Ignition

6412983 -7000 rpm, 5500 red line, used with 427/390hp

6412572 -7000 rpm, 6k red line, used with 427/425hp equipped with RPO K66 Transistor Ignition and also 427/390hp with RPO K66,1st design

6412984 -7000 rpm, 5500 red line, used with 427/390hp equipped with RPO K66 Transistor Ignition, 2nd design

6412549 -7000 rpm, 6k red line, used with 427/425hp

That should clear things up. If you have a tachometer that's for a transistorized ignition DO NOT try to run it on a stock non-transistorized ignition. Just the same, if you have a non TI tach DO NOT try to run it on a transistorized ignition. The polarity as well as the the circuity is different between these systems and damage can happen very easily.

 

Mine is the 6412572. It took about a year of searching daily online to find all the K66 components & the tach. Cost about $3000 total. 

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I ran 2 amplifiers on a switch in my FI split window. Could buy new distributors at the Delco-Remy (where the distributors were made) employees store for about $60 and Amplifiers were about the same. Was also a special coil (Red ? Memory fades).

 

Would have to look but remember rewiring passive tachs to work with TI, just had to connect to the top of the coil with Delcotronic instead of the bottom. Have the Delco schematics... somewhere, it has bee a while.

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