lifter preload

Q: We have a 1974 Ford F-100 pickup we use as a tow vehicle. It has a 360-cubic-inch two-barrel engine running Crane stock replacement cam and “anti-pump-up” hydraulic lifters. The heads are fitted with TRW valves and springs that are close to OEM in the lift and spring pressure department. The rockers are stock ratio and

I just installed a new cam in my small block Chevy. The engine runs great, but I’ve noticed that at idle and at some cruising speeds the engine makes a noise that sounds more like a mechanical lifter camshaft. I bought a hydraulic flat tappet camshaft but this one sounds more like a solid lifter