There's a 420306 but it would be too big for a 273.
- Hi-Flow AM
- E420306
- RPM Range 3500-6500
- Advertised Duration 286°/294°
- Duration @ .050 Lift 242/246 deg int/exh
- Valve Lift .510in int/exh w/1.5 rocker
- Lobe Separation 108 deg
- Advance 0 deg
- Valve Lash .018/.018"
- Complete with Lifters and Assembly Lube
- We recommend Pro-Duty Hardened lifters with .012 lube hole in bottom - Part# ML752 SEE BELOW