i replaced my distributor and set the timing on my 87 gta to 8degrees now the tach says I'm running 2500 to 3000 rpm on the interstate but from the sound and me knowing the car this isn't correct, i also noticed that the tach doesn't respond like it use to to different rpms the idle still reads right but the higher you go it seems to get worse, also could this be because of the higher base timming, i have the digital gauges any help would be great
p.s. i know the stock timing is suppose to be 6 degrees but I've read around and a lot of people say they seem to get better performance form 8 also how high can you go and what are the perks to a higher base timing i also use only 93 octane

 

I can not conceive of any way that your tach is off from what you discribe. There must be some other reason.

What tranny do you have? If its an auto, maybe the tranny is not using OD.
Just a guess.

 

yea i thought it was that too but i shifted back into drive and the rpms jump up higher and put it back into od and it shifted back into od its a 700r4
i was thinking it was the ignition control module in the dizzy but its new and i would hope thats not the problem but it leads me to think that because the tach is driven off the magnetic pickup in the distributor and that signal has to go through that module to get to the tach.