I’m reading an article about retrofitting a Gen 4 LS engine (L77) to older vehicle (Hot Rod Magazine, 4.19). I came to this paragraph and got stopped in my tracks. What do these two sentences mean? Why does the cam phase get retarded with engine rpm? Wouldn’t the cam phase get advance with rpm?
As cams get bigger, you need to limit the amount of VVT advance to avoid piston to valve clearance issues. GM’s phaser scheme starts out at – depending on the model year – 7 or 17 degrees advanced from the cam profile’s as-ground position, then retards as much as 52 to 60 crankshaft degrees from there.