Engine displacement does have an effect on how well an engine holds a tune, but most car engines fall in roughly the same range. What has the largest effect is engine design and maintenance history, with more mild engines tending to be more forgiving and better kept ones tending to be more reliable. Your 15FE is a very mild little thing, and it seems to not have been abused if it fired right up without any effort.


As for that phillips screw...Get. It. The. Hell. Out! I HATE phillips screws. They strip far too easily. Pull it out, take it to a hardware store, grab yourself an allen headed bolt to replace it.