I need to know where the valve lash should be set? Distance? specs. It is on a b16a1....the only time I have to change it is tomorrow...after that I will have to wait another 2 weeks before I will have time. Thanks

 

What kind of motor? and please don't say honda or four cylinder.

 

On a B16a you set it to:

.17mm +-.02 on the intake cam
.19mm +-.o2 on the exhaust cam

If you don't have feeler gauges in metric then the closest gauge you can use that will put you in the +- range with standard gauges are:

.006" on the intake cam
.007" on the exhaust cam

 

I know the valves are set to .007 and .006 exhaust intake....but Im asking bout the lash valve.

What Is "Valve Lash"?
[RB] Valve lash is the mechanical clearance between the cam lobe and valve stem or transfer rocker when the valve is fully closed. It's usually checked with a feeler gauge and is some non-zero value on with "mechanical" non-self adjusting valve lifter mechanisms.

Differential expansion characteristics cause the cold clearance to be different than the running clearance and margin is built in to make sure their is always some clearance, especially on exhaust valves. An exhaust valve that doesn't close completely doesn't transfer enough heat back to the head and can "burn".

Cam lobes have entry and exit profiles (called ramps) which are designed to limit the opening and closing acceleration of the valve to limit mechanical stress and also noise. Still, the tighter you set the valve lash (less clearance) the more open valve duration you get which tends to boost top end performance slightly. The looser you set the valve lash the more bottom end is boosted and the more valve train noise you get.

If you have all the valves adjusted too tight idle quality and low end performance may suffer slightly with an attendant small gain in top end horsepower. Looser valve lash does the opposite and results in a noisier valve train.

If you have some tight and some loose that might also effect smoothness since different cyclinders will have different power contributions at different RPMs. Some of the above is a little simplified but you get the drift.

Why Does Valve Lash Need Adjusting?
[LE - 99/12/28] Too much lash can accelerate wear on the rocker arms, cam followers, cam lobes, valve stem tips and valve seats. How much it does depends on the engine and how far out of spec the lash is. Too much lash also tends to make more noise so you're more likely to know it needs adjusting.

Too little lash is more dangerous both because it leads to more serious problems and because it doesn't make any noise. Luckily the NSX valves do not tend to get tighter so unless they are adjusted incorrectly it should not be a problem.

But just for your info, too tight a lash may allow the lash to close up as heat builds up in the engine - especially if the engine begins to run hotter than normal because it's being worked hard. This gets worse as the engine gets hot because valve clearances tend to close up as the parts heat. That's why the NSX shop manual specifies that you should do the gap adjustment when the engine is cold. Some other engine service manuals will specify seperate hot and cold adjustments. The loss of lash can prevent the valves from fully seating which results in loss of compression and valve overheating. Exhaust valves rely on cooling through the valve seats much more than intake valves, so loss of lash in the valvetrain often results in a burned exhaust valve



Are you saying the valve lash has the same setting? thanks

 

that is the valve lash. b18c .006 intake, .007 exhaust. stick a feeler between the cam lobe and rocker arm. that is how you measure VALVE LASH!

 

^^^^^damn is there an Echo in here?


[Modified by hondaswaper, 2:22 AM 1/21/2003]