Reply to "Tuning help needed"

That's funny. That's the EXACT rpm at which all hell would break loose for me. At 4,200 the tires would literally come off the ground on mine too. I attributed that to the Edelbrock Torker power curve with the big 4v iron heads. Up to 4,200 it was a little flat but this helped in launching the car and minimizing tire spin.

The A3 heads are different. They have more torque off of idle and much smoother through the rpm range. A crisper feel throughout. Easier to drive the car this way because it doesn't hit you at one rpm like a supercharger kicking in.

Jets are now 72/73 on a 750 DP Holley 4179. I had an 850cfm secondary metering block on it which uses a power valve. That was set at 2.5in-hg, or in other words would open only at WOT after the engine was ready. I couldn't get the timing right on the opening since I was tuning on the street and this type of tuning can only be done on a race track since this is flat out death wish type of tuning and totally unsafe and irresponsible to do on the street. Also well over 130mph to tune it too.

But the secondary power valve IS an alternative to the large secondary jets but is complicated to handle.