Homer has short υ in ἀλύω, ἀνύω, βρύω, δύω, ἐρύω, ἠμύω, τανύω, φύω, and in all denominative verbs except ἐρητύ_οντο and ἐπι_θύ_ουσι, where υ_ is metrically necessary; long υ in ξύ_ω, πτύ_ω, ὕ_ω; anceps in θυω
2. Hom. has ι_ in the primitives πί_ομαι and χρί_ω; but τιω and τί_ω (τείω?); -ιω in denominatives (except μήνι_ε B cross769). κονί_ω, ὀί_ομαι are from κονι (ς) -yω, ὀι (ς) -yομαι.
3. Where Attic has υ_, ι_ in the present, and Epic υ, ι, the former are due to the influence of υ_, ι_ in the future and aorist.
2. Attic has ι_ in primitive verbs in -ιω, as πρί_ω, χρί_ω, χλί_ω, but ι in τίω. Denominative verbs have ι_; but ἐσθιω.
Herbert Weir Smyth [n.d.], A Greek Grammar for Colleges; Machine readable text [info] [word count] [Smyth].