ok, so i have a 383 stroker in my 68 with hei distributor. i have a aftermarket tach hooked up at the tach signal from the distributor. when at idle or sometimes when rev'ed up, the tach will jump. anybody have any idea what it can be?

the distributor is a aluminum billet with new cap and rotor along with new coil, but its not a name brand distributor. possible bad cap and rotor?

 

The tach gets an ignition signal from the distributor, which in the case of an electronic ignition, comes from the module inside the distributor. A jumpy tach would be either from a bad module, or the tach itself.

 

well, tach and module are both new....

 

Have a clean 12 volt power source to the distributor, and not hooked up to the original resistance coil wire?

 

hummm.....now that i need to check and do.....thanks again.