I agree with Jack completely. I drove a Speedster with a bone stock 1600 from Idaho to Ottawa, Canada and a year later the same Speedster from Sacramento to Ottawa, Canada with a basic single carb 1915. The difference was dramatic. First engine was reliable but hardly suitable for travelling on the freeways while the 1915 was much better suited to the task and more fun to drive the distance. Same stock transmission both times. No cooling problems either time but we didn't spend time in hot, congested traffic. No external cooling parts on either engine.