Ok i have done some research on these boards and to me it sounds like the tach filter is going bad, but before i go and buy one i wanted to get some advise.

'85 110k miles, When i 1st start it up the tach reads 0, even driving it stays at 0 until about 15-20 minutes into driving then it seems to read normal and seems to rev up like it should..

Sound like the tach filter?

Thanks!

 

Could be a loose/faulty connection as well. Try bypassing the filter to see what happens.

 

I have never heard of a tach filter doing what your discribing, but Im not saying it couldn't be the filter. Most of the time you just get an erratic reading with the tach jumping all over the place and / or the tach will just give a false low reading...WW

 

Thanks, maybe a connection is loose... I will check it out

 

sounds like a loose connector at the distributor. There is a 4 pin plug, and the ones at the coil

 

I don't even have a tach filter on mine yet. I've got one, but I have no idea how to wire it in. Whenever I hit a pothole of hole in the road, My dashboard goes all crazy and stuff. I know I need to put it on, but the old one I took off had both the wires burned off and I can't trace them back to install the new one because I do not have anythiing to go on.

 

I am now wondering if it can be the coil going bad. I went out there and checked the wire that goes to the tach side of the coil and it was fine. i started it up and it was running rough, which it has been doing for a week or so now just on start up.

Anyways i popped that plug off, and when i plugged the wire back in and wiggled it around and the engine instantly ran smoother and the tach seemed to be working properly(was idleing around 680-720 rpms).

Might this be the coil going bad?