Holley vacuum secondaries

newBDR · #1 (**permalink**) 12-29-2004, 08:37 AM

Anyone play with different springs in their vacuum pod? Any noticable change to report? I have a 670 Street Avenger on my 302 and was toying with the idea of getting their spring kit to see if it makes any difference I can feel - opening the secondaries a little sooner or later. According to Holley, a lighter car can benefit from opening them sooner for a bit better performance.

Big-Foot · #2 (**permalink**) 12-29-2004, 11:12 AM

If you start tuning with various springs in the secondaries, just be cognizant of one main idea;

If you FEEL the secondaries opening, the spring is too weak. Vacuum secondaries, when tuned properly, will open as the engine needs the additional airflow, opening them earlier will just cause a bog (temporary loss of power) followed by a kick in the pants when the engine RPM catches up to the point of being able to use the additional air/fuel. It's that "kick in the pants" that some people mistakenly take as something that is good, when in fact, you are actually accelerating at a slower rate..

powerpagers · #3 (**permalink**) 01-09-2005, 06:32 PM

I USE THE TIGHTEST SPRINGS THAT WILL STRETCH, TRY IT.

GeorgiaSnake · #4 (**permalink**) 01-09-2005, 08:21 PM

I bought the Quick change kit with the assortment of springs. I can't tell you how much better the car runs with the lighter spring. I'm running a 4150 on my stroker motor and based on the Holley charts the standard spring starts to open (on a 400 ci motor) at 1960 rpm and doesn't fully open until 7130 rpm. I'm running the yellow standard lenght now and the throttle response is very different, opens at 1420 rpm and fully opens at 5020 rpm.

Randy