Lazy tach

Message

Lars Nielsen · #1 Post by **Lars Nielsen** » Wed Apr 16, 2014 12:21 pm

How does these mechanical tachs normally respond?
As I drive the car hard my ears and the tach do not agree. Above 4000rpms the needle moves slowly, but the engine sounds more like its is at 5000rpms.

Reving the engine neutral, the needle reacts promtly and freely to redline.

My dwell gauges goes to 2400rpms and matches fine.
Gauge was rebuild last year by NH speedo.

Thomas Sottile · #2 Post by **Thomas Sottile** » Wed Apr 16, 2014 1:32 pm

You should be able to match RPM to MPH my 64 SC reads about 4000rpm to 80 mph.

Lars Nielsen · #3 Post by **Lars Nielsen** » Wed Apr 16, 2014 3:43 pm

Its not the steady speed/rpms thats the problem, but the reaction on tach when you blast quickly thru the gears at full throttle.

Mike Smith · #4 Post by **Mike Smith** » Thu Apr 17, 2014 3:48 am

Have you asked NH Speedo ?

Lars Nielsen · #5 Post by **Lars Nielsen** » Sat Apr 19, 2014 7:06 am

Yes, and they also agree that the tach itself is fine as it revs perfectly in neutral.

Lars Nielsen · #6 Post by **Lars Nielsen** » Thu May 08, 2014 4:51 am

update. Solved.

Found a clogged main jet. Car and tach now revs to 5500 just fine.
The clogged jet was only a problem under load I guess, since the car would rev to 5500 in neutral just fine.

The Official 356Talk Forum

Lazy tach

Lazy tach

Re: Lazy tach

Re: Lazy tach

Re: Lazy tach

Re: Lazy tach

Re: Lazy tach