Sound clip - before/after valve adjustment

[stevetwors]

Is there a video or audio clip of an NSX engine that is in need of a valve adjustment, and then one of the same NSX after the valve adjustment is done? My engine seems a little noisier than a 97 I saw recently but I'm not sure if it's because I have 145,000 miles or if it's because I need a valve adjustment. I bought the car with 132,000 miles and I can't remember what the owner said when the last adjustment was made. He did say the timing belt and all hoses were replaced just before the sale however.

Besides just being noisy, what else is bad about driving around with a valve adjustment overdue?

 

[swerve2007]

there are 2 scenarios- both kinda extreme as they will manifest themselves after a prolonged driving time unless you drive hard:
1. if the valves are tight they will 'cup' the valve crown's edge (distort it resulting in need for replacement).
2. if the valves are loose the exhaust ones will get burned-up as they will not be able to fully transfer combustion heat to the head.

 

[swerve2007]

i need to add an information about my previous stament.

1. the valves must be very tight in order to get 'sucked-into the seat' and distorting the machined edge of the valve in the shape of a tulip.

2. it s not a very well known fact that there is actually a lot of heat transfer between the valves and the head. if the valves are loose (i mean loose, not just on the low side of a spec) then there is a lot more heat being retained and also hot gasses bypassing the valve crown into the exhaust port right along the thinnest edge (where it meets the seat- 45 deg angle)- that fries them up pretty well. i am not certain how long that would exactly take but some of the old alfa engines i bought/worked on surely have not seen a valve adjustment in decades, paired with their high-rpm nature it leads to failure.

i am absolutely certain that a lot of people working on modern engines will never see those issues as the motors are either better maintained or have better metallurgy.
cheers!

 

[Briank]

Tight means there is not clearance between the follower and the valve which will not let the valves close which will cause a loss of performance and burnt exhaust valves.

To loose mean means the valves will not fully open and extra noise.

 

[Briank]

1. the valves must be very tight in order to get 'sucked-into the seat' and distorting the machined edge of the valve in the shape of a tulip.

Valves are closed by the valve springs, no sucking involved.

2. it s not a very well known fact that there is actually a lot of heat transfer between the valves and the head. if the valves are loose (i mean loose, not just on the low side of a spec) then there is a lot more heat being retained and also hot gasses bypassing the valve crown into the exhaust port right along the thinnest edge (where it meets the seat- 45 deg angle)- that fries them up pretty well. i am not certain how long that would exactly take but some of the old alfa engines i bought/worked on surely have not seen a valve adjustment in decades, paired with their high-rpm nature it leads to failure.

To tight or no clearance cause burnt valves :wink:

 

[swerve2007]

aparently this a matter of semantics- you are describing condition as seen by the valve shim/retainer while i am referring to the conditions at the seat/guide/valve interface- i guess i am not following the lingo.:biggrin:
neverless we are saying the same thing.
didn't mean to confuse anyone.
cheers!