[Gaz64]

Lighter cars "can benefit" from a lighter spring. There is no rule that says "should have" a lighter spring.

There are many variables involved.

Vehicle weight, gearing, engine capacity, carb size.

An 870 on a 482 needs to spin 7200, before it flows 870 at 1.5 inches, assuming 85% VE.

Secondary spring free lengths are not all of the answer when comparing springs. Coil count, wire diameter, compressed length when fitted, spring rate etc.

Go lighter on the spring until full throttle acceleration is felt as a bog, then come back one. Or go to the lightest spring, (white) then come up until the bog disappears.
The QFT adjustable secondary is an easier option.



Gary