• Hi Guest!
    If you appreciate British Car Forum and our 25 years of supporting British car enthusiasts with technical and anicdotal information, collected from our thousands of great members, please support us with a low-cost subscription. You can become a supporting member for less than the dues of most car clubs.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

BJ8 Tach Won't go past 2400 rpm

Share this page

Patrick67BJ8

Patrick67BJ8

Obi Wan
Silver
Country flag
Online
Just installed my Tach and it will not go past 2400 rpm when slowly reving the engine. This is part of the final leg of a 6 year frame-up restoration.

New wiring harness installed.
Negative ground.
Pertronix ignition.
Worked correctly before removing for full restoration.

Thanks,
 
Patrick67BJ8 said:
Just installed my Tach and it will not go past 2400 rpm when slowly reving the engine. This is part of the final leg of a 6 year frame-up restoration.

New wiring harness installed.
Negative ground.
Pertronix ignition.
Worked correctly before removing for full restoration.

Thanks,
Click to expand...
I should also have noted that the Tach falls off to zero after hitting the 2400 rpm mark and it will rev past 2400 if I goose the gas pedal while parked(it's still on jackstands).
 
I read a while back that the solution to this is to put a second loop of the white wire through the thingy on the back of the tach so it gets a better signal. Something to do with the Pertronix not giving as strong a signal to the tach as the points

Andy.
 
I have the same prob with my bj8 it won't go past 2000 rpm I talked to nisonger they said it was the petronix look up their web they made a modern board that they configured with the petronix look it up
 
rjc157 said:
I have the same prob with my bj8 it won't go past 2000 rpm I talked to nisonger they said it was the petronix look up their web they made a modern board that they configured with the petronix look it up
Click to expand...
Andy & rjc157, It's the same tach, tach wiring and the same pertronix. Something else...maybe? I did disconnect the "loop" to remove the Tach so I might craw up under the dash and see if the metal clip aound the plastic piece is inserted into the Tach far enough. I recall one of the metal legs is longer than the other.
 
The loop works as a transformer so is fairly sensitive to its orientation. Maybe try moving it around a little with the engine idling. Add a second loop if you haven't already, maybe you were just lucky previously. Lots of comments about Pertronix and no tach, many cured by the extra loop.
 
Back
Top