However, most cams intended for street use are ground with several degrees of advance. We have a hint because if a camshaft if ground with no added advance, the intake lobe centerline will be the same number as the LSA–114 degrees After Top Dead Center (ATDC). The only thing we don’t know from these number is the cam’s intake centerline. But this comes at the cost of reduced torque in the middle of the rpm band. Stock GM LS engine cams feature LSA anywhere from 116 to 121 degrees because GM is concerned with creating a very smooth idle. Less overlap generally produces a more stable idle while more overlap makes the idle lumpier. If the number was 110 degrees, this would increase the amount of overlap. The greater number of degrees means there is less overlap between the intake and exhaust lobes. When referring to LSA’s, the larger the number, the more degrees of separation between the intake and exhaust lobes. The HR refers to this as a hydraulic roller camshaftwhile the 114 refers to the lobe separation angle (LSA). The next information engraved on the cam was HR 114. The second lobe number 3711 refers to the same family of lobes–this one spec’d at 269 degrees advertised with 216 degrees at 0.050-inch tappet lift with a lobe lift of 0.330 and a theoretical valve lift of 0.561-inch. With this intake lobe: 0.328 x 1.7 = 0.5576-inch, which COMP rounds off to 0.558-inch. All you have to do to determine valve lift is multiply the lobe lift times the rocker ratio. The lobes are also listed with various theoretical valve lifts–the one we’re interested in would be the LS1’s 1.7:1 rocker ratio that delivers 0.558-inch of lift.
The 3709 lobe is listed as 265 degrees of advertised duration with 212 degrees at 0.050 and 0.328-inch lobe lift. We found it under the heading of Xtreme RPM for LS1 lobes, Hi Lift. We continued down the list until we found the 3709 number, which because it is listed first on the camshaft, is the intake lobe. Once we found the hydraulic roller section, the first column lists each lobe by number. In the catalog, you will see the cams listed by configuration starting with flat tappet hydraulics and then hydraulic rollers–which is what we want. This is the COMP Cams equivalent of the Rosetta stone for cam lobes. Under that heading toward the bottom we found a tab for the Cam Lobe Master Catalog. On the home page, we looked for the “Information” tab and then clicked on “Catalogs”. To decipher these codes, we accessed COMP’s website at. Each family of cam lobes has its own numerical designation with the same basic configuration, usually encompassing multiple individual durations that also might include changes in lobe lift. The 3709/3711 numbers are references to lobe designs. Other examples include small block Chevys -12, big block Chevys -11, and 5.0L small block Fords -35. The LS engine is designated 54 and this number is generally the first two numbers that define the actual cam part number. COMP Cams uses two-number designations for all its engine families. If we didn’t already know this was an LS cam, the first thing we would want to do is determine the engine family. That gives us our first clue where to look for the rest of the numbers. Jeff Smith: First of all, the CC refers to COMP Cams. Can you tell me the specs on this cam from these numbers? On other cams I’ve looked at, they just list the part number – which is easy to look up, but this cam has a bunch of numbers I don’t recognize. The end of the cam is stamped 3709/3711 HR 114 followed by CC and 7661-11. My buddy says it’s a mild cam that’s bigger than a stock LS6 version, but he didn’t have any more information. I purchased a used hydraulic roller camshaft from a friend that was originally used in an LS1 engine.