I recently installed an HEI distributor in an old 68 Chevy 350 that had the old style point distributor. I put all new cap, wires, coil, and module in the HEI distributor. When I first started it up it idled slow and would backfire through the carb. I then advanced the timing and it ran smoother and didn't backfire as much. I then advanced it as far as I could to the point where the vac advance module hits the intake and it ran a little better but still sputtered and backfired a little. I then noticed that the engine cranked very slowly before it would start. Is it possible I could have gotten the distributor off a notch or 2 and it would run the way I have described, and if so how do I get the dist in right to correct this problem. When I said I advanced the timing I turned the dist counter clockwise. A guy at the auto parts store told me the thing wouldn't even run unless the dist was installed correctly. So now I am wondering if it could be the timing chain or something else. Even though the motor is in a 68 truck I have my doubts the the motor is a 68. It uses the smaller spark plugs (R45TS). I didn't have this motor running before I installed the HEI so I don't know if the timing was out of whack before I started. Thanks in advance for your help.