Join Date: Aug 2005
Location: Halton Hills, Ontario, Canada
There is one other possibility, just to possibly complete the tach diagnosis picture. Original D'arsenval tach meters are by nature easily damaged and definitely do not like being contaminated by any metal shavings inside the meter. I had this happen with my 6K tach years ago. Don't ask me where the shavings came from, but somehow they got into the tach. They made the needle hesitate above 2k rpm at several places and then actually get stuck partway around the dial. If I tapped the gauge it "released" the needle. Useless for driving!
Hopefully the OP's case is related to the Pertronix and the signal being properly calibrated when it reaches the tach. Otherwise it needs rebuilt. Tachman is a good rebuilder, there are others out there.
[/SIGPIC]67 Fastback GT -- original colour (Frost Turquoise), original 289 A code engine. Pic is of me and the Mustang taken in May of '67, with original F70-14 Wide Ovals. Same car is now restored to "as new" but 3 speed tranny swapped out for 4 speed back in the mid '80's, with tach dash, original Equalock rear, Koni's, Opentracker UCA, LCA, roller perches and idler arm, roller bearing pedal cluster, Cibie headlights, 4100 carb (old 4300 put in storage probably forever)