So I took out my 83 z28 tonight for its first longer test drive in quite a while after doing a ton to it. Car drove and ran great but with 1 main problem. My speedometer didn't seem to read right at all would barley go above 25mph and the needle would just kind of dangle around. Also my tach which I have read is a problem with these cars was reading probably twice what it actually was. Tomorrow I will be taking the dash apart to do some investigating but just trying to get some ideas of what could be wrong or what to look for thanks....

 

The speedo problem could be caused by using the wrong transmission adapter or drive gear or sleeve or wrong size wheels and tires or could just be a faulty speedo head. The tach problem is most likely a failed tach filter.

Here's a good explanation of the speedo drive gears.

http://www.camaros.net/shop/speedo.html

On my 84 Camaro my tach filter looks similar to this one and is located on the fire wall to the driver's side of the distributer.

http://www.elcaminocentral.com/users...ch_filter1.jpg

Make sure the body of the tach filter is grounded well or it won't work.

http://i1234.photobucket.com/albums/...tachhookup.jpg

 

Thanks for the info. I will check this filter where would I be able to get another if I needed to replace. Also one of the things I did was replace factory distributor with a MSD street fire one so would that have anything to do with it?