Lets start with some facts. MY car was a 305 auto vert swapped to 5 speed. Done before I purchased. They did a **** POOR job and cost me lots in repairs 24 hours after buying.

Now, the car still has a auto chip in it, found out by scanning it with a snap on scanner. BUT, according to the scanner, it's still outputting the speed (scanner shows how fast im going and RPMs etc). At high RPMs the speedo starts picking up. say at about 150km/h It'll read 30mph and keep rising as I increase speed (I have mph speedo in car, car was imported to canada).

Just throwing it out there as I'm completly lost on what it could be. My tach also reads off by about 500 rpms.

This is in my 1991 Z28 drop top.

Thanks in advance!

 

bump, really need some help guys!

 

Its not uncommon for tachs to be off by 1000. Get an autometer..

 

the tach isn't my problem, not knowing how fast I'm truly going is!

 

bump?

 

any ideas?

 

Try a different speedo head maybe.