Hey, my stock SS tach will not rev above about 2000 RPM. It seems to be fine below that, idles right about where I would expect, but once I rev, it goes to about 2000 RPM and just hits a wall. I looked up old posts and the only one that I could find that could explain it suggested debris inside the tach sticking to the magnet. However, there was no response to this solution is to whether or not it worked. Anybody have any thoughts as to what my problem could be? The tach wire is new from the tach to the distributor. Thanks for any help all.

Brad

i had a 72 SS that done that very thing several years ago. i got frustrated one day and ran RPMs(while in park running) up to i think about 4500 or so and hit the dash real hard with hand. it came loose and worked great ever since. i am sure this method is not in the chevy manual but it did work for me. mabe someone has a better fix. good luck

hmmm, I do recall that method working for several of my automotive headaches as well...

However, that would seem to support the idea that there is debris in the tach that is fouling it up. If no one else suggests any other possible problems, maybe I will take the tach apart this weekend...

Anyone else have any other ideas?

Brad

Be very careful taking the tach apart, the needle is attached to a very delicate spring system. Try moving the needle by hand first to see if this will clear it. If not try gently holding the needle and blowing (by mouth) the debris out. (Do not use compressed air)

Is this an HEI ignition? If so, it could be the module and foretolding of things to come if it's not a mechanical issue.

I was thinking it might be the module too. I just replaced the cap, rotor and advance stuff, but left the coil. However, I have the Autogage tach (cheap) that was in the car when I bought it, and when I hook that up it seems to work fine....keep the ideas coming if anyone has anymore...
Thanks all

Brad

Same problem with my 70 SS- tach stops at 3500 RPM.Have tried hitting it---not sure of the correct spot or how hard.

My factory tach also has the same problem at 4000 rpms (also reads too high).

Had the same problem with my stock Knee Knocker (66).........alway read low....It was one of those things that I was going to do something about one of these days........well in the Electrical Forum I just posted about my HEI Problems................after going thru and replacing everything inside the Distributor....then buying a New Distributor and the Car still not starting........I finally found that the Tach went Bad and was shorting out the Ignition......Dis-connected the Tach Wire and the car started.........Just wanted to pass along that info to save someone else $$$$$$$ in case the same thing happens to someone here........As we get older....we don't get any Smarter............Just "Wiser"..........

Ken