Valve spring pressure when valve closed?

Tom,

If you go to the web site of any of the cam manufactures, they should have specs for the valve spring pressure when the valve is closed, and at a specific lift. I think around 100 pounds is typical for a performance street cam, and a lot higher for a racing cam.

What you are describing sounds way off. I'd measure the force somehow before I mounted the heads.

There should be around 100-140 psi of 'closed' spring pressure on all street valve springs. This engine would have put out little power, and had you not noticed, you could have chased your tail for months over this. It suggests that the springs are either very weak or were not shimmed correctly for the valve stem length used... and I'd be careful to check for coil-bind after mounting the heads on the block, since we're questioning the work done. With the engine OFF and the valve covers removed, stick a length of 0.040" wire solder in between the spring coils, and have someone crank the engine 1 complete rev with a wrench. If the solder is pinched, even a little bit, from the inner or outer spring coils, you will break parts when the engine is run hard. Incidently, I can destroy a set of new valve springs in 3 drag-strip passes; the mileage means nothing- it's the conditions they experienced. You can check spring pressures vs manufacturers spec's at home with a vise, a bathroom scale & a caliper (off the head of course).