Join Date: Mar 2002
Location: Austin, TX, USA
If you have an ohm meter, measure the resistance from the tach line from under the hood, back to the tach. You should see high resistance if any at all. If you use an analog volt meter, you might see a reading on the 10K or 100K ohm scale. I suspect you'll find you have much less resistance.
Is this a factory HEI? Around 72 is when GM started phasing in HEI.
68 Coupe, 350 w/ Edelbrock Performer RPM heads, cam, intake, 700R4, Dave's small body HEI