Spring Surge: What Is It?
Spring surge is when the spring can no longer fully control its own mass. This situation is caused by the spring being excited by a force that coincides with the spring's natural vibration frequency. Imagine a hammer striking the end of a spring. The impact (not unlike that of a valvetrain about to open a valve) will take time (be it very short) to travel down the spring. The effect of the impact is to close up the space of the top coil and the one immediately below it. This closing of the coils passes down the length of the spring until it reaches the bottom coil. There it is reflected and returns to the top. The point to note is that as it reaches the spring seat, the poundage the spring delivers is substantially reduced. In severe cases the lower coil of the spring can actually jump off the spring seat. When a spring experiences this sort of internal motion, it is in no way able to control the valvetrain.
Take The Easy Way Out
Stumped by Vizard's verbosity? Call up COMP Cams and ask for the CamQuest6 cam-selection software--it costs 10 bucks. It works on any PC with Windows 95 or newer. It's just like the award-winning DynoSim engine simulation software, only it's a lot cheaper. After installing the program, just fill in the prompts for your engine specs on the left side of the screen. You'll be asked your engine type, induction, engine size, planned useage, cylinder head type, exhaust type and a few other questions. After a few nano-seconds, a list of camshaft profiles pops up on the right side. As you scroll through the list of computer-selected cams, the dyno graph on the lower left of your screen changes to reflect the power output of that cam combination. The best part about CamQuest6 is that the program gives you exact COMP Cams part numbers. Just pick the power curve you want, dial 800-999-0853, and give 'em the part number listed on the CamQuest6 screen. You can even tell them you heard about CamQuest6 from PHR and they'll give you your 10 bucks back on your cam order. And just how accurate is CamQuest6? We plugged in the specs for our smog-legal 383 small-block from Project g/28, and got a power curve that looked so close to our real dyno numbers that it nearly scared us.--Johnny Hunkins