They each have their up's and down's. Subaru is a much higher quality engine with a Mikuni carburetor (throttle and choke easy to adapt), overhead cam, great charging systems up to 200 watt, exhaust port on top and easy to make an exhaust for, power is good. So it's a very reliable, quiet, smooth, easy starting engine, easy to work on.
Tillotson is a clone based engine with overhead valves, so it's noisier by nature, exhaust port is oriented out the back of the head so making exhaust is much more involved. I upgrade to Tillotsons TCT carb (going to test their larger TFT carb next week) but the linkage movement direction is opposite of the Subaru and that complicates adapting... but the fact the motor will not start without some throttle added, and the governor had to be retained to open the throttle to some degree when not running so it would start easy so the whole conversion process is much more complicated and involved to tune out the bad manners it inherently has. Charging system is adequate, but even with dual coils and regulator you aren't going to be powering a whole lot without hitting it's limit. Most people wouldn't notice so not a big deal. BUT, power wise it's making up for all the things I didn't care for. And the fact the TCT/TFT carbs can be tuned with the motor in the boat without taking anything apart (so I can tune on the water, and don't even have to go to shore). That means no going home to swap jets and drive back out to the river to test again. So that's a big plus. Parts are readily available, very affordable, and for those who like to experiment with performance parts they're out there everywhere.
So ultimately it boils down to making lemonade. The Subaru is gone, and making the best out of what's available with the Tillotson isn't the only way forward but moving forward is the only option and it's the most affordable bang for the buck that can be made to work and feel equally as nice if not maybe better than the Subaru. Longevity is the only thing that is in question, but with regular maintenance / oil changes etc.. I don't think that's going to be a big issue. Parts are cheap, and you can buy anything you need individually or as an entire spare engine without breaking the bank. I have to admit I've really been enjoying my outings with this boat, it's set speed records for the one piece hull that I've experienced so far and that alone is enough to impress me. Motor has some serious grunt.
