When an injector fried a cylinder not long after a top end overhaul, we were reluctant to throw any more money into this old 4520 tractor. It only made sense to yank the newer 404 turbo out of our retired 7700 Turbo and mate it to the 4520 frame. The combine 404t had over 4000 hours on the engine but ran like a champ. With this new engine the tractor now revs over 2400 RPM and makes for excellent PTO operations such as a grain vac. The extra RPM allows her to cruise just over 20 MPH WOT. It was sad to see the 7700 turbo put to rest, as it was the first combine we learned to drive. It was a fun project,
