What causes valve lash?

Too much or too little valve clearance can result in poor performance or a rough idle because the engine can’t “breathe” normally and operate at peak efficiency. Too much clearance means the valves will likely clatter and, over the long term, cause damage to the valves, camshaft lobes or rocker arms.

Where do you put valve lash?

EO/IC rule (Exhaust Opening and Intake Closing). Set the intake valve lash when the exhaust valve is beginning to open. This will put the intake lifter at the base circle which is where you want it to be. Then set the exhaust valve lash when the intake valve is about halfway down on the closing side.

What does it mean if your valve lash is too little?

If it is too little, the valves may not seat properly. If it is too much, you create valve train noise, and excess load on the valves and valve train components. As the picture shows below, valve lash basically cuts off the lower portion of the cam profile. This lower section is where the cam profile is designed to gently open and close the valve.

What does a lash do on a pushrod engine?

Valve lash is the mechanical clearance in the valvetrain from the valve tip to the rocker in a pushrod engine using solid lifters.

What’s the best way to adjust a valve lash?

Plus, there’s a downside to overly tight valve lash. Perhaps the most popular method of adjusting valve lash is with a polylock on a stud-mounted rocker. There’s an adjustment nut and a locking screw that work together to properly position the rocker. “We’re talking opening and seating velocity.

How does zero lash affect a valvetrain system?

With zero lash, the system would be forced to have zero velocity at opening and closing, and this would limit engine performance. “As valvetrain systems have become more rigid and allow for higher accelerations, opening and closing velocities have counterintuitively migrated down a bit,” continues Godbold.

How to set the 16 valve lash setting?

Turn the crank only Clockwise. #1 crank ‘v’ mark at TDC0, cams on heels #1 , set lash on #1 Rotate crank 180 degrees CW set #3 lash. Rotate crank 180 degrees CW set #4 lash. Rotate crank 180 degrees CW set #2 lash. your are done.

Valve lash is the mechanical clearance in the valvetrain from the valve tip to the rocker in a pushrod engine using solid lifters.

How does a net LASH system work on an engine?

Not the least of which is the net lash system where the engine builder doesn’t have to run through setting hydraulic lifter preload on all 16 valves. In a net lash system, a set distance between the lifter (on the cam lobe’s base circle) and the rocker arm creates the preload on the lifter based on pushrod length.

What happens when the Lash is too loose on a valve?

“The head is then moving the rocker arm further away from the pushrod.” If the lash setting is too loose or excessive, the valvetrain takes a severe beating. The rocker arm acts like a sledgehammer by building up momentum with the extra distance and pounds the valve tip.