My tach is whack...again

Get back!  A whack tach in Chilliwack?

Sorry, it's early and my coffee hasn't kicked in yet.

Ron, are you using an ignition box?

No, just a Mallory distributor.

Ron

Hey Ron, if your only set back is a out of scope tach, then life is good buddy... we've heard stores here over the past several years of tachs that freak out after 2 or 3 months of running good, and then their ALL-over the place. mostly it was those funky Mexican tach's that would blow-up, but I thought that was corrected? From what you're telling us looks like about a 10% plus or minus on the error your reading...  Personally no biggie for me, but if you're one of them "gotta have it right" fella's then god bless ya and give Henry a call again... Good luck.

Speedster "D" tach-less!

Confucius say, "Better to be tach-less than tach-y."

I hate having gauges that are off.  My speedo is 6 mph off (over) at 70 mph, which I can live with (barely), but I want my tach to be accurate.

Ron

I thought crack was whack

No worries, just remember our call to arms here... "Welcome to the Madness" I personally do not think the term "accurate" applies.. ;-) I'd settle for running and getting me HOME!

Good luck Ron...

Speedster "D"

I'm a bit late on this reply but I seem to be having the same kind of problem. Well, at least in that my tach has gone crazy again. I have 195 miles on my car/engine  (Thunder Ranch) that I built. Engine was built by CB Perf. The original tach went bad at about 60 miles. I pulled it and sent it to North hollywood where it was rebuilt. I put it back in and all seemed well for 25 miles.  I have no idea if it was on the money when I reinstalled it but the numbers seemed OK. All of a sudden the dial started jumping all over again, from no rpm's to 5000 and back.  Shut the engine down and restarted her and all was fine for a couple of minutes then back to the same old story.  Any suggestions?

I think you and I need new tachometers. 

As I mentioned in a previous post, I had Henry, at Intermeccanica, send my tach back to North Hollywood for recalibration.

Didn't work for me. 

Looks like it didn't work for you either.

Would the type of coil have a effect on this? There are 2 different types of coils by Bosch,the no resistance one and the "resistor" one. I know that with a Compu-fire/Pertronix you have to use the resistor type,or there may be issues.

 Look at your Coil and see if there are any identifying marks on it,or post a picture if you are not sure. 

 Since these tachs are electronic,maybe they need a certain coil?

 Maybe call North Hollywood and ask them,if coil is not a issues,then atleast make sure your grounds/+ are good in your electrical system going to the tach. Good luck.

 BTW I have no idea if my tach works or not,since I am revving to 9K on a daily basis,and my tach only goes to 6K........

I checked all my ground wires and everything seems tight.  All I see on the tach to identify it is Bosch. Drove for awhile today and again all things seem fine then the tach just goes wild. All over the spectrum from within range to off the end and then absolutely nothing.  I have never really driven a car using the tach but since it is there and I just paid a couple hundred dollars to have it rebuilt I guess it would be nice if it worked. The fuel gauge is pretty questionable also. Since I did the required modification I am surprised that I get any indication. At least it points in the right direction.  Could the ground strap off the engine be a possible problem spot?