Since, completing this write-up, we took the car on a 1300 mile round trip. It did GREAT ! We got 15-16 mpg on the mostly highway trip. One of the alternator brackets broke; the piece that mounts on the exhaust manifold and is not drilled. The auto parts store exchanged it and we assume it was just a bad part. Before leaving for our trip, we installed a new, stock RX-7 radiator. The original radiator had a lot of miles on it, and the cooling capacity was degraded, so rather than take the chance of it failing hundreds of miles from home, we just replaced it. The cost was only $110.
Two weeks after returning, the car started to develop a vibration that we traced to the original RX-7 universal joint at the rear end. I guess the hard shifts took their toll on the wimpy piece. Weíve decided to replace the stock UV joint with one from a 350 Camaro. It will require milling and welding a Chevy pinion yoke to the RX-7 pinion flange, but when itís done, it should hold up fine.
We havenít taken it to the dragstrip yet, but that will happen very shortly. When it does, I will post another update here.†††