Once upon a time I had a Jackson gear drive in a SBC super gas motor in my Vega, ran it for a year like that. During a freshen up, I switched to a Jesel belt drive. I allways used a breaker bar to rotate the motor when running the valve train. The difference in the effort required between the two told me the gear drive had a whole lot of pairisitic drag. I would never run one again. My .02.