I've searched on here, on hybridz and all over about the dreaded pertronix ignition tach bounce fix.  I find lots of places talking about it but nothing on fixing it besides getting a different tach.   I have the  3.0 ohm coil that came with the kit and I bypassed the resistor just like the installation instructions suggested.   My 1973 240z now starts a thousand times better and faster and the throttle response is great and seemed to pick up some power.  The problem for me is between 3000-5000 rpm the tach will drop to zero then bounce like crazy.  I don't experience and problems with misfiring or the actual rev of the motor, just the tac.  Has anyone found a solution to this common problem yet? 

I had the bounce, but most of the time the needle would get to 4000 then freeze and drop to 0 and when the revs came down under 4000 the needle would jump back up.  I replaced the tach but it didn't help.  I hunted through the archives too to find a fix but never found one that worked until I pulled the old distributor and replaced it with the Ignition123 dizzy, that fixed it for good.

I just finished the PerTronix upgrade using the new Ignitor II electronic ignition with solid state dwell compensation plus Flame Thrower Coil on my '72 240Z, 11/71 production with original tach. I opted for the 1.5 ohm coil so I could retain the Ballast resister in order to mimic the original wiring as much as possible just to try and avoid tach issues. Plus (most importantly) I used the John Hull wiring diagram, see link. Carefully following the wiring diagram, and spending about 3 hours total, I buttoned everything up, turned the key and my car fired right up with the tach operating normally. My idle has increased to about 1100 over the original 900 which I will adjust but the car seems to run very smooth with better acceleration and no tach issues. Hope this helps...

www.zhome.com/ZCMnL/tech/ZXPertronix.htm



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