What is the largest valve size you can run on a standard bore 413 without notching the block ?, looking at some RPM heads with 2.14 / 1.81 valves, Thanks !

I’d expect some problems with the ex valve if you run much over .500 lift.

Not sure on the intakes.

I just measured some heads with 2.14/1.81 valves. I got about 4.04 outside to outside on the valves. stock bore is 4.18. the real issue is that big block valves don't open on the cylinder center. big valves may not be safe; especially with higher lifts. i'd definitely be mocking things up first.

1.81’s touch the bores on a std bore 383 at about .550 lift...... and since the 413’s bore is .125” smaller...... I think it’ll touch with less lift.