On a 4.080

I've never tried a BT head on a small bore, 390 based engine. Most of my BT customers are building toward the higher/larger end of the spectrum. I have run quite a few modified Edelbrocks on 390s though - its safe to assume that similar rules will apply. Like you, I have seen no issues with larger intake valves. I have had one engine that was at 4.070 we ran with 1.71 exhausts - it just clears on the engine stand but scrubs in operation. I'd recommend staying to 1.65ish exhausts. Realistically the BTs greatest benefit lies in the intake and chamber anyhow, and its nearly too large on port volume unless you're running a 4.25 stroker.

Barry Rabotnick
Survivalmotorsports.com