Overlap Estimator: Section 1 is for street towing, 2 is for regular street,
3 is street performance, 4 is for street/strip, 5 is for race, and 6 is Pro race.
To make the most of this chart, you will need to take into account where, in terms of valve size per cube, your engine falls. For, say, a 3.8 engine with decent-sized valves (SPI), the overlap selected needs to be toward the short end (left side) of the segment that fits your application. For Single Port, add some LCA if you are running stock valves. If it's a typical 4.2, then choose something around the middle of the relevant segment. If the engine in question is a big-block or a really big-inch small-block (both of which are typically under-valved), then select the overlap toward the larger, righthand side of the relevant segment.
USE OVERLAP @ ADVERTISED DURATIONS ONLY!
Line A is for 3.8 engines, B is for strokers and line C would be really huge strokers,
(no real applications for the V6 crowd yet).
As you will notice the chart overlaps somewhat, a cam in category 1 on
line B (4.2 truck cam, street towing) @ 30* O/L would make a decent
"regular street" 3.8 cam also at 30* O/L. Chew this over a while and then
I'll lay a formula on you guys later, that generates full duration specs from the
the info off the chart we're using here!