you just need to get the timing set properly, the right tooth lined up and it should do it... i have a similar problem with my large body HEI unit in my 289...... except what the problem is is theres a small groove in the bottom plate of the distributor that fits over the heater hose fitting on the intake.... gives me about 6 degrees of sweep.... takes a little time and patience to get it in place but once its there you're happy and it should lock down and never move again