ZL-1

[jrm3]

Team,
I see where some of the ZL-1's had tachs but where they 7 or 8 tachs?  and did some come with 140 speedos ?

[william]

A few COPO 9560 ZL1s were ordered with Special Instrumentation, which included a 6000/7000 tach. Same as L78.

Two ZL1s are known to have been built with COPO 9737 which included the 140 speedo; #3 & #65.

Not all ZL1 build configurations are known so there could be others.

Question for those knowledgeable with electronics. How did the factory tach hook up to the K66 transistor ignition system on the ZL1?

[bertfam]

How did the factory tach hook up to the K66 transistor ignition system on the ZL1?

Bill, wouldn't it have just come off the negative side of the coil like the standard ignition?

Ed

[bertfam]

Well, after re-reading the TRANSISTOR IGNITION PAGE, apparently:

The Tachometer Issue

Camaro TI distributors, like most others, came with a mechanical tachometer drive mechanism. It was speculated that the racer would use a mechanical tachometer. A mechanical tachometer can be setup but you may find it difficult to run the cable. The author has set one up successfully in a 1968 Camaro without butchering his vehicle, but it is challenging. You will find that your factory electronic tachometer will not read accurately if you try to drive it from the coil terminals (either + or - terminals). Apparently Stewart Warner used to make an adapter to drive their tachometers on a TI system. It is unknown if the adapter will drive a factory tach.

A special service bulletin from Delco-Remy for connecting a test tachometer to the system was released April 15, 1965. (Bulletin 1.2D-19). To use a tune-up tach, first locate the two-wire distributor connector. Find the side that the solid white wire is on. Connect your tachometer positive (+) lead to this point (easiest to attach on the other side of the distributors mating connector). The tachometer negative (-) lead should then be connected to the coil positive (+) terminal. (Yes - you read this right!) The author has successfully used a tune-up tach this way, but it seems to only work on tachs that have a separate power wire that attaches to the battery positive (+) terminal. Aftermarket performance tachometers (ones that don't have a separate 12-volt power wire) seem to not function when attached this way.

At least six of the sixty-nine ZL1's came with a factory tachometer. It is believed that they utilized standard production tachometers, but it is unclear how they addressed these issues.