Holley Vacuum Secondary Springs

[j69302]

I have a 69 302, with a Crane Energizer 260 cam, Edelbrock Performer RPM Heads and Intake with a Holley 600 VS carb. I have a TKO600 with the 2.79 open 8inch for now

Well I have went from Black(original and the stiffest) to the purple which is right in the middle and I havnt noticed much of a difference. I took the purple out and ut the lighter of the 2 yellows in which is second from the lightest and I noticed a small bog but overall it seemed to run better.

So anyways I'm just curious to see what spring other people are running with this or similar combination. I know too light of a spring will make it bog a little then once the rpms are up you are supposed to be able to feel it kick in, then you go up in tension until the bog goes away.

 

[D.Hearne]

I've always used the lighest or the purple. With the purple on a 600 sitting on a mild 302, F4TE roller cam (this is the explorer cam) ported E7 heads and a Ford A321 intake (high rise dual plane) it would open the secondaries about a second or so after nailing the pedal. Ditto on a 390 with a 750 Holley. It should work similarly with your setup.

 

[2nd Mustang]

I have a similar setup. I guess it depends on how you like to drive.

Following Holleys tech line, I made one of my 600VS run like an all out double pumper. Playing with the springs on another 600VS made the car run better, but still cut the secondaries in too quickly IMO. So, on my new 600VS, I just left it the way it came from Holley. It runs just fine.