Originally Posted by JDMopar
Hey Scratch! wave I'm in the process of building a 273 for my 65 Barracuda, and will be using a set of 302 heads. Was it much of a big deal to step up the valve sizes to 1.88 - 1.60's? I'm not sure if the 273 needs that or not, but I'm open to it if it will help airflow and not hurt the velocity. It's gonna be .030 over with NORS 8.5 pistons, a D4B Edelbrock intake, MP electronic ignition. I'm using a 318 crank and bought new Scat rods cheaper than I could get the old ones redone! I'm leaning towards a Lunati retrofit hydraulic roller with 447 lift. There's another Lunati hydr roller that is slightly hotter, but I need to see what my builder says before I throw the money down. I'll be using Dougs headers in the Barracuda.
I had my 302 heads pressure checked to see if they were cracked, and they aren't. Those things are bad to crack between the valves


I have read & IIRC on a 273 and #302 heads the 1.78 valve is better as the 1.88 is shrouded and needs notches on the block cyl bores to clear. or was that a 2.02 valve?
but going bigger on the exhaust side from 1.50 to 1.60 helps it a lot. then just open/clean up bowl area, back cut valves ect.. or have them fully ported 1.78/60

how well do the #302 castings look in the bowls/port openings? last couple I had are crappy castings but my 91 #714 are pretty clean from the get go as for as casting flaws go. very little clean up and bowls are shape nicely/roundish with no big casting lines in there.