The following summary data shows why you should not try to draw any conclusions about overlap by comparing lobe separation angle. This summary data includes duration at .050" lifter rise above the base circle for hydraulic lifter cams and above the top of the clearance ramps for mechanical lifter cams. These numbers can be directly compared. Also included are inlet and exhaust points of maximum lift, which are typically referred to as "centerline" even though they are NOT the centerline on all but the Duntov due to asymmetrical lobe design. Inlet max lift is degrees ATC, exhaust max lift is degrees BTC. LSA is cam degrees and is just the arithmetic average of the points of max lift angles.
"Effective overlap" in square-inch-degrees is as reported by the Engine Analyzer simulation program. This is the total valve "curtain area" during the overlap period, which takes into account valve size and rocker ratio. It represents what is actually going on inside the engine. These overlap data are not exact because EA assumes a symmetrical lobe when you input .050" timing data, but you can consider them comparible in relative terms. A longer stroke engine can handle more overlap than a short stroke engine and have the same idle characteristics/vacuum, which is why BB engines typically have more effective overlap.
Cam.....Dur.......IML/EML/LSA.....Effective overlap (sq-in-deg)
LT-1...231/231...110/122/116...........4.2
L-79...221/221...110/110/114...........4.1
Duntov 220/220...108.5/112.5/110..4.8
30-30..239/239...110/118/114.........5.5
L-46...224/224...114/114/114..........4.7 (also used on all L-82)
300hp 194/202...108/116/112.........0.6 (3896929, 1408839)
300hp 196/196...109.5/112.5/111...0.7 (pre-'67 37333431 obsolete repl by 929 or 839
L-36...214/218...110/120/115...........3.6
L-72...231/231...108/120/114...........6.2
Duke
"Effective overlap" in square-inch-degrees is as reported by the Engine Analyzer simulation program. This is the total valve "curtain area" during the overlap period, which takes into account valve size and rocker ratio. It represents what is actually going on inside the engine. These overlap data are not exact because EA assumes a symmetrical lobe when you input .050" timing data, but you can consider them comparible in relative terms. A longer stroke engine can handle more overlap than a short stroke engine and have the same idle characteristics/vacuum, which is why BB engines typically have more effective overlap.
Cam.....Dur.......IML/EML/LSA.....Effective overlap (sq-in-deg)
LT-1...231/231...110/122/116...........4.2
L-79...221/221...110/110/114...........4.1
Duntov 220/220...108.5/112.5/110..4.8
30-30..239/239...110/118/114.........5.5
L-46...224/224...114/114/114..........4.7 (also used on all L-82)
300hp 194/202...108/116/112.........0.6 (3896929, 1408839)
300hp 196/196...109.5/112.5/111...0.7 (pre-'67 37333431 obsolete repl by 929 or 839
L-36...214/218...110/120/115...........3.6
L-72...231/231...108/120/114...........6.2
Duke