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Well I have finally gotten my 81 running really well. I just bought a MR gasket recurve kit for the HEI dist. By the way I replaced the computer controled carb and dist, with a 77 Vette carb and GM HEI dist. The computer is totally out of the picture. Like I said the car is running good so why not mess with it until I screw it up again right? But anyway the recurve kit came with three sets of springs and the instructions say to use the set of springs that give you the advance you want. They give you a chart but how do I know what advance I want? Anyone out there do this to there car. What set of springs are you using? Any advice you can give would help out. Thanks
You should try a forum search under recurve kit or distributor recurve in the archives. You'll find more than you need. Lars is the resident guru.
I just slapped in the lightest springs and basically adjusted my timing to 38 degrees total. You'll need an adjustable timing light to get total advance.
Study the chart until you understand what it means. The main reason to recurve the distributor is to make the advance arrive at a lower rpm. Up to a point, more advance gives more torque. Unless you also change total timing, top end power is unaffected. I'd just try the springs that provide the fastest advance and see how it works. If you get pinging or other problems go to the next stiffer set.
If you don't have an adjustable timing light you can still set total. Measure the circumference of the damper, divide that figure by 10, and make a new mark on the damper that distance from the TDC mark. With vacuum advance disconnected, rev the engine until you're sure it's through advancing and align the new mark with 0º on the tab and you'll be at 36º total.