Originally posted by gofstbuick
Actually, I understood the real old LT1 or Z/28 valve springs to be just regular production valve springs. The new LT1 valve spring has 101 closed pressure at 1.78 installed height. I'm using the Chevrolet second racing design camshaft valve spring (3927142). That spring is closer to what many think is the early Z/28 valve spring. It is 110 closed pressure at 1.7 installed height, with a 358 pound rate. A very heavy valve spring. I'm using a Poston 107T cam (according to Lunati, an exact match of their cam, except 4 degrees of advance and a technician at Lunati confirm they used to make cams for Poston). But the recommended spring for my cam is 108 close pressure with 350 spring rate. So my springs very closely match the requirements for the camshaft I'm using. My engine is needs to be rebuilt (long story), but my cam bearings are trashed (1 to 3). The cam has 45000 miles on it and the lobes measure perfect. Assuming the cam is straght and the engine needs new cam bearings, I will reinstall this cam and run those same valve springs. The factory Buick spring requires 78 (-/+ 4) pounds closed pressure and the closest valve spring to those specifications is the Compcams 979 or 980. IMHO that would be my valve spring choice for the factory cam. The heavier spring may accelerate wear and I would hate to advise you to install the heavier spring only to hear you need to tear your engine down because of premature cam wear. I think these engines are less forgiving on excessive spring pressure than a SBC. The valve springs in my engine very closely match the cam requirements.
