I have a 3.0 SC engine with stock internals and Weber carbs in a '69 912. I'm regearing a 901 box for this car and plan to start with a 914 gearset A F N V ZD. Actually, I may just build up a 4 speed box with F N V ZD, because the 3.0 has so much torque that I rarely use first gear.

My questions is regarding a tall final drive ratio. The ZD 5th works out to about 70mph at 3000rpm. I also have an H 5th gear set and this would give me 70mph at 2500rpm, but I'm concerned about engine cooling at the lower rpm. Does anyone have experience with a tall final drive ratio like this?

Thanks,
John Dimock