We have a 350 that is a real basic set up it is a hydraulic cam, cast piston stock crank, vortec heads. I cant seem to get a good reading on the timing. I checked the degree of the cam once we installed it but be cause I didnt have the damper at the time it wasnt marked at tdc I figured we could use a piston stop to measure it after the heads were on well it turns out that because the angle of the plug in the vortec is closer to the chamber the piston stop will not stop the piston at least not with my stop. so I know we are not dead on on tdc but we are close. The dist is a msd with no vacuum advance it has the 21 degree bushing with the blue springs. I am shooting for a total advance of 34 degrees so i figured I would set the timing at 13 degrees advanced at 900 rpm. At this timing the engine backfires through the carb so it is advanced to around 21 to 25degrees to get it to run decent. I also should mention that it has a crane hi6 ignition the timing also seems to jump around some I am not sure it is related to the box interfearing with the timing light or what... any ideas????