6 months ago, I tuned my 69 vert 350 Auto (no AC) with new points/condenser and a rebuilt carb. I set the dwell to 30 and the timing to 9 BTDC as per Chilton's recommendations. Idle was set to 800-850rpm in park, and 650rpm in drive with brake depressed.
Well the other day, my car started idling rough. Now it always has had that rumbling shaking that we all love. But this was different...more like an ceiling fan that is missing a blade... all out of whack. And it only happened after going 50-60 down the highway. And it only happens intermittently. And more importantly it only happens when I am at a light.
So, yesterday, I checked the dwell and it is 30.5. The timing however is 10 degrees BTDC with the car idling at 800. If I lower the speed screw down to 650rpm, the timing is 8 BTDC. Chilton states to check auto trans at 650 rpm. It doesn't say park or neutral or drive. It is out of whack, but I cannot figure out if I should go with my reading at 800 in park (10 BTDC) or 650 in park (8 BTDC). Or am I totally off the mark.
