Valve wear bet between Doc and Forest who is corect?

[BajaRon]

My sympathies to Forrest...

 

[dave01]

That's an awful lot of hot chocolate

Sent from my Xoom using Tapatalk

 

[pauly1]

All of this discussion pertains to a mechanical valve actuation system; hydraulic lifters would change much of this thread.

Lift is dictated by the cam shaft grind minus valve lash/clearance. If the valve seat/valve face were worn, then the lift would be increased by the worn dimension, but negligible on overall performance. Valve lash/clearance is also affected by temperature of the motor; as the exhaust valve is hotter than the intake valve, typical clearance will be set greater on the exhause valve than the intake valve to accommodate the difference in thermal expansion.

Wear on the camshaft and lifter, in this case the "bucket", will be greatest at maximum lift when most force is generated by the valve spring. Only wear on the camshaft lobe will decrease lift.

Wayne

 

[effgjamis]

Valve does not seat tighter.........!!! regarless of wear or new. In fact I do believe the valve spring loses some strength ( tension ) due to the seating of the valve face wear and seat, therefore there would be less tension on the valve face/seat.
How can one say that WEAR will tighten valves regardless of where the wear is, bucket, valve stem end, or face of valve? The bet " wear tightens the valves " I say NO !

 

[Lamonster]

That's why I posted the video Bro, watch it again if you haven't yet, it might help. nojoke

 

[docdoru]

...interest expense apply on the outstanding debt...10 days

 

[NancysToy]

Valve does not seat tighter.........!!! regarless of wear or new. In fact I do believe the valve spring loses some strength ( tension ) due to the seating of the valve face wear and seat, therefore there would be less tension on the valve face/seat.
How can one say that WEAR will tighten valves regardless of where the wear is, bucket, valve stem end, or face of valve? The bet " wear tightens the valves " I say NO !

If you had a BMW, you'd understand. :roflblack: They are notorious for it. I'll draw a picture that explains it better, next time we meet up. It's easier to understand with a diagram to look at. Wear at the valve/seat interface lets the valve go deeper into the head closing up the valve lash. Basically the spring pushes the valve stem closer to the cam. It's all about geometry.

 

[effgjamis]

Scotty.... are you saying that the sping tension is the same new or with valve wear?

The spring, as I see it, always provides pressure to keep the valve closed, whereas the so-called bucket/lifter/cam presses on the valve stem tip to open the valve.

Scotty... is the spring a push or pull.. I always thought it was a pull as it was seated on the head with the valve stem ?

 

[effgjamis]

That's why I posted the video Bro, watch it again if you haven't yet, it might help. nojoke

I noticed in one pic that you had a manual rocker arm adjustment, whereas in others shims were imployed to increase the gap between the bucket/rocker thereby allowing the valve spring to completely close the valve or burning may occur.

 

[NancysToy]

Scotty.... are you saying that the sping tension is the same new or with valve wear?

The spring, as I see it, always provides pressure to keep the valve closed, whereas the so-called bucket/lifter/cam presses on the valve stem tip to open the valve.

The spring actually lengthens a bit, and thus loses a tiny bit of tension, as the valve wears into the seat. It is the spring always holding the valve fully closed that pushes the valve stem tip (and cam follower) closer to the cam or (rocker). That closes up the clearance if the valve/seat wears faster than the cam/follower. I could explain this better with some props or pictures, I'm afraid.

 

[effgjamis]

The spring actually lengthens a bit, and thus loses a tiny bit of tension, as the valve wears into the seat. It is the spring always holding the valve fully closed that pushes the valve stem tip (and cam follower) closer to the cam or (rocker). That closes up the clearance if the valve/seat wears faster than the cam/follower. I could explain this better with some props or pictures, I'm afraid.

By the sping losing a bit of tension then the valve does not get tighter.

 

[NancysToy]

By the sping losing a bit of tension then the valve does not get tighter.

If you mean tighter, as in less valve lash, yes. If you mean more pressure against the seat, no. The difference in tension is small, however, probably less than 1%.

 

[effgjamis]

thanks Scotty..

I WIN >>>>>

 

[jedd]

Put it up for a vote:2thumbs:

Jim:thumbup:

 

[G-Man]

Just have another beer. Beer is right. The more beer, the more righter. Forest wins. Beer! :doorag:

 

[Lamonster]

Just have another beer. Beer is right. The more beer, the more righter. Forest wins. Beer! :doorag:

Just read my sig line.

 

[BajaRon]

By the sping losing a bit of tension then the valve does not get tighter.

Forrest, you have a knack for turning fact into confusion....:dontknow:

 

[effgjamis]

Forrest, you have a knack for turning fact into confusion....:dontknow:

that was the wager.....

 

[Raptor]

You know, I don't want to stir up the pot any more than it already has been, but I do see both arguments. Technically the valve itself does not get tighter; the valve lash gets tighter due to wear in the seat and/or valve. The inportant thing to keep in mind is the result, which is loss of complete seal of the valve and eventual loss of power and valve/seat damage.

Scotty, I did just what you said and drew it out on a piece of paper and it made sense to me after that. The video that Lamont posted was great as well. So what is being accomplished by re-shimming the buckets is compensating for lost lash so that the valves can close completely and keep a good seal. This is why it is important to get them checked.

So really, it might sound like hair splitting here but the physical valve does not get tighter; it is the lash that does. However, I think that we accept the general term "valves are tight" as loss of lash due to wear in the valve seats.

Regardless of who thinks who won, I value the technical nature of this discussion. Very good stuff guys! :2thumbs:

 

[bruiser]

On most every head I've pulled for valve problems the seats and valve edges were worn. In some the valve edges were so worn they looked like a knife edge and little to no seats left. Bottom line, valves need to be checked at the proper intervals and the proper lash maintained. On IC equipment I work on, compression checks and valve adjustments are part of the pm service.