By comparing the results from degreeing the camshaft with the cam card, we can verify that the valves will open and close when they’re supposed to and the lift and duration is as advertised. This easy operation ensures that not only has the camshaft been manufactured according to the cam card’s specs, but also ensures that the engine builder didn’t make a mistake-a mistake that could possibly take out expensive components if installed incorrectly. Each and every camshaft is ground to achieve a certain event at a certain moment, so it’s important to ensure that those events happen when they’re supposed to after the camshaft and timing chain set are installed. In layman’s terms, degreeing a camshaft is the simple operation of checking that the installed camshaft functions happen as specified on the cam card. ![]() Summit’s Pro SBC cams are CNC ground using CBN diamond wheels from American bearing steel billets. With an advertised duration of 204 degrees on the intake side and 214 on the exhaust at 0.050-inch lift, our engine should have a perceptible idle lope with a good powerband between 1,500-6,000 rpm. Be sure each piston is at TDC, right on the money.To actuate the valves in our small-block we opted to go with Summit Racing’s recommendation of their Pro SBC Stage I hydraulic roller cam (PN SUM-8800). But like I said, 0.040" across the pins (so the "rock" of the piston in the bore is eliminated from the measurement) will be fine. This might be 0.043" w/the piston pushed as far down as you can rock it, and that will make the other side higher, say 0.037", if you follow me. I measure across the wrist pin, because the piston tends to rock in its bore, but at 0.040" across the pins, you'll be fine. If you can, borrow a depth mic, it will make the job SO much easier (shown below). You could even use a straight edge and feelers. Then, as long as you have a "normal" amount of deviation (0.001"-0.002"- if over 0.003" I'd start looking for the cause), use the tightest figure to compute your quench for the engine's head gaskets. I believe it's worth it just for peace of mind, if nothing else. But checking all 8 piston heights will be the best route by far- it's not unusual for a rod to be "long", and that's not something you want to find out during a WOT pass. You want to check AT LEAST the 4 corner pistons- that will give you a figure for both sides (the sides can differ from one another) plus any front to rear deviation that could have occurred during manufacturing and machining of the block main saddles, decks and also the machining of the crankshaft and rods. Be sure each piston is at TDC, right on the money. ![]() Click to expand.You could even use a straight edge and feelers.
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