78 tach pegged
Thread Starter
Instructor
Joined: Nov 2020
Posts: 143
Likes: 28
From: Colorado Springs
78 tach pegged
Hi all. Took my 78 L48 auto for a spin today. Tach was fine. Shut it down after 30 minutes and the tach pegged at 7000. Restarted it an hour later and the Tach is still pegged. Anyone have this happen?
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
On the distributor cap, drivers side, is a wire harness terminal. The pink wire connector is 12V POS for the dizzy. The other wire, I believe is brown and is the Tach Wire.
Follow that down to the Intake to where it joins the Tach Filter. (Looks like a condenser) If the connection is wonky it can raise havik with the tach needle,
Check real close at the soldered joint. They tend to "appear" connected, but from yrs & yrs of extreme heat will have a poor connection.
As I recall, those filters were not very cheap. If you need to re-solder it, everything can be unhooked from the dizzy cap & Intake and moved to your bench for repair.
Follow that down to the Intake to where it joins the Tach Filter. (Looks like a condenser) If the connection is wonky it can raise havik with the tach needle,
Check real close at the soldered joint. They tend to "appear" connected, but from yrs & yrs of extreme heat will have a poor connection.
As I recall, those filters were not very cheap. If you need to re-solder it, everything can be unhooked from the dizzy cap & Intake and moved to your bench for repair.
Thread Starter
Instructor
Joined: Nov 2020
Posts: 143
Likes: 28
From: Colorado Springs
Have a tach gilter
Thanks BKarol for the update. I do have a tach filter but have not pulled it yet to check for a bad solder joint. Shark racer gave me a quick fix that worked so far
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