Hamilton Cams Springs 103# Seat Pressure For High Lift Cams (Formerly 110#)

Stock springs have 78-82lbs of pressure seat pressure on average at 1.380". If you are over 35psi(boost or drive presure) and 3,800 rpm, stock springs do not fully control the valvetrain. This allows a few negative things to happen. First, valve float, which can cause serious damage to the valvetrain. Second, intake and exhaust valves can be blown open by boost and exhaust drive pressure which allows reversion. Reversion can hurt your power potential by allowing exhaust gasses to enter the cylinder on the intake stroke. Inert gasses in the exhaust, when re-introduced into the cylinder shield the fuel particles from oxygen in the cylinder. This does a few things that negatively affect power. It increases the time delay from start of injection to start of combustion, it decreases the maximum pressure and maximum temperature reached in the cylinder and it increases the total time needed to completely burn the available fuel. Correct valve spring pressure is a very important piece of power production.

Hamilton recently slightly lowered the pressure on their springs from 110lb to 103lb. Nose pressure has been lowered from 220lb to 180lb. Watch out for other companies that have nose pressures over 250lb. Your cam will have a shorter life with 250lbx2 (500lb) versus 180lbx2 (360lb)over the nose of the cam. Don't just ask what seat pressure is when you are shopping for springs, ask what the pressure is on the nose(1.031" with OEM cams or .958" with the 188-220)

If you are running over 4,500 rpm with a large cam, Hamilton suggests going with their 103lb springs with different heat treat and shot peen, for better longevity in extreme applications, as well as their light-weight 4130 or titanium retainers.

Warning: not all 24valve springs are created equal.... recently other companies market products that are called 110lb 24 valve springs, when in reality they have 117-119lb of seat pressure and almost 250lb nose pressure at .320 lobe lift. Also, they are designed as an entry level spring for a dodge neon, but are re-boxed and sold to the diesel crowd. This spring can cause major lobe wear to anything over a stock lift cam. ALL of Hamilton cams have more than stock lift.

If you run a cam with more than .320" lobe lift and anything other than the 103lb spring you run the chance of experiencing coil bind before maximum valve lift is achieved.