What should clearance be on valve lift Springs?
What should clearance be on valve lift Springs?
At full valve lift, your valve springs should have, at the very least, .050” of clearance between the coil. The outer spring, inner spring, and damper spring should all be checked for proper clearance. This is simply accomplished by slipping .050” feeler gauge between the coils with the valve fully open.
Can a valvetrain have too much spring pressure?
But can a valvetrain ever have too much spring pressure…yes, definitely. A normal flat tappet cam core is limited to about 145-155 pounds seat and 400-pounds open pressure. The simple reason is the material; cast iron cannot stand more pressure and will go flat. It cannot handle the same pressures as a roller cam, which is made out of steel.
Why do valve springs not harmonize with cam profile?
“Beehive” springs (right) don’t have the same predominant natural harmonic frequency that cylindrical springs do, making them less likely to “bounce” and stop following the cam profile. Clay continues, “The valvetrain can reach a point where it is moving so far that the cam lobe and the valve spring do not harmonize.
Can a stock valve spring be used on a high lift camshaft?
In most cases stock valve springs do a good job for stock camshafts. When changing to a high lift Crower performance camshaft, stock springs physi- cally won’t travel the distance your Crower high lift camshaft requires. The spring coils stack solid and the destructive condition called COIL BIND exists.
Why are valve lifters important to the pushrod engine?
The lifters (also called “tappets” because of the clattering noise they produced) rode on the cam lobes in the block and actuated the valves directly. Valve lifters play a key role in the valvetrain of pushrod engines. They go all the way back to the earliest days of the internal combustion engine.
Why is lash adjustment important in valve lifters?
Lash adjustment is critical because too much clearance makes the valves noisy and reduces valve lift, duration and performance. Too little clearance can also create problems because it causes the valves to open sooner and close later, reducing heat dissipation through the valve seats when the valves are closed.
What causes a valve to float in a hydraulic lifter?
At high speed, hydraulic lifters may “pump up” and hold the valves open causing the valves to float. This can happen if the valve springs are not strong enough to maintain normal valve control, and the lifters try to take up the slack that really isn’t there. This overextends the plunger and prevents the valve from closing all the way.
Why are valve lifters still used in drag racing?
Even so, most hydraulic lifters can’t match the performance and reliability of solid lifters over 8,000 RPM. That’s why high revving engines in NASCAR, drag cars and circle track cars still use solid lifters.
