Tom,
I'm have a 390 Holley.
How do you check the timing when driving? I tried to get my son to get under the hood with the timing light, but he wouldn't do it. He claims he's claustrophobic. I told him he was being wimpy.
Just kidding. I assume your electronics monitor that on your El Camino.
I've done several things over the past week. Based on Panic and Tony P's advice, I ran my vac gauge into the cab and then drove it aprox 800 miles (I commute 118 miles a day). Changed the base setting at every fill up. I worked my way up to 37 degrees advance at 3K and my mileage has improved (but still not very good-14.5.) I took your advice and bought an adjustable vacuum advance. I drove it tonite and adjusted the base timing and vac cannister (about 12 times) and found that the highest vacuum is achieved at 41 degeees at 3K with vac can as loose as I can get it. But I only picked up 1 inch of merc and it doesn't start as easy as it was (I checked starting at every adjustment.)
I also did one other thing to the distributor. I ground out the stopping point on the mechanical advance in an attempt to get to full mechanical advance before 2500 rpm's. I was successful. It hits at 2300 and it eliminated my 'stutter' at 2200 and it improved acceleration and vacuum upto 3K.
You made me feel better about the vacuum readings at cruise speed because the best I could get was 12 inches of merc on a flat stretch nand all the local guys are V8 dudes and they all told me that I should be 15 to 18.
Panic and Tom,
I'm just under 5 inches of merc at mild throttle. Are you saying that I need a power valve that opens at less than this?
I'm going to turn the total timing back to 38 and leave the vac can as loose as possible. But I have to say that at 41 total timing was the first time I was able to leave a stretch of rubber on the road in second gear (33" inch tires and a posi! - thanks for the all the help so far)
