CHECKING THE SPRINGS- This seems to really confuse people, especially those familiar with Holleys. These springs and rods control the power mixture- VERY similar to the Holley power valve. The lighter the spring, the faster , or lower vacuum level they close at . Manifold vacuum controls them-at a high vacuum( idle or cruise) they are held closed by the vacuum. When vacuum drops sufficiently, the spring overpowers it and opens, or raises the rod. The tip of the rod is smaller and therefore richens the mixture. The trick is to have them closed at idle and cruise, and open as soon as the vacuum drops signaling more load. Most performance engines seem to like the orange spring or one close to it. To check it requires a helper. I AM NOT RESPONSIBLE FOR YOU RUNNING OVER YOURSELF-WITH OR WITHOUT HELP!! Here is a way to check it and get close without 246 trips around the block. Unscrew the metering rod covers just enough to turn the covers-turn them to expose about half of the little piston and retighten the screws enough to keep the lids from rattling around.-GENTLY-or you will bend the covers. Start the car -see the little pistons go down? Now have your helper put it in gear (brakes on) – do they stay down? If not, you need lighter springs until they do. To change them, unscrew the plates and remove the pistons and rods-the spring is under the pistons-a magnet or small screwdriver will get them out. Put the next lightest spring in and try again until they stay down. Now comes the fun (dangerous) part-repeat the test only this time have your helper gun the car hard enough to hit the stall speed and let off quickly- make sure your hood doesn't slam you in the head- watch the piston as he lets off- it should jump up and return down…if it doesn't go a little heavier on the spring- if you are out of options, stretch the ones in there just a little bit. Now return to the tuning part above.
