Valvetrain inspection

[bastarddsm]

What should we be looking for when inspecting valves/springs/retainers/keepers.

I'm dissembling my head to clean it and reassemble it. I'm staying with stock valves, as the seats seem to be holding up really well. The head in question is off an imported low mileage n/t. It has the stock 6T valves in it. I have run it for 2 seasons now. 1 season at 500whp with DKS272's, stock valve springs and turning it 8000, and 1 season at 600+whp with Kiggly Street Beehives, DKS272's, and turning it 9000.

The stems all look smooth and shiny with no scoring or unusual wear.

The keeper grooves are dark and do not show any signs of wear.

The keepers themselves look good with no wear, but they do move on the stem. That is if you place one on the step and push it into the grove, it has about .010" axial play on the stem. I have had new valves and keepers with more play.

The tips of the valve stems do have sort of a sharp edge, I assume this is normal wear?

The retainers are not showing any signs of keeper movement. However the spring seat is shiny like the retainer is rotating on the spring.

I'm concerned with the possibility of "dropping a valve" or some other catastrophic failure. I know those sorts of problems are usually caused by "floating the valves" or other conditions where the valve movement is out of control. I don't appear to have any signs of that.

Are there any signs of impending failure to look for?

 

[donniekak]

I won't trust 2 piece valves ever again. I'm building an engine right now because one of my stock exhaust valves had the head separate from the stem. This was with the high tension supertech duels. I came off the antilag launch, shifted out of 1st at the 8500 rpm limiter, and died going into 2nd. When I got it apart the head of an exhaust valve had destroyed my head, and one wiseco piston. I think the combination of high egts from the antilag, and the stiff springs killed it.

 

[BogusSVO]

Shiny where the spring sits is one thing, but if you see the spring digging into the retainer then you need to make a change.

What spring installed height are you using? and what is the pressure on the seat and over the nose of the cam?

 

[bastarddsm]

They are not digging in. They are installed at 1.462"@85lbs. Assuming my cams have .400" lift they are 214lbs @1.062" on the nose. These figures were measured on my rimmac spring tester (which seems so read a bit low), and jive with the numbers kiggly states of 85lbs at 1.475 installed ( I measured 81lbs @1.475 when new), and 325lbs/inch.

 

[BogusSVO]

So you should have appox .100 worth of shims under the spring, or a thick spring seat.

 

[bastarddsm]

Nope, I have a .030" shim and the stock locator at about .040" The kiggly steel retainers have the spring seat lower in relation to the keeper, than a stock retainer.

 

[danl]

If it is pulling clean to redline without the feel of "misfires" or unexplained torque dropoff then you are probably fine as long as you keep the parts fresh. Valvesprings are a wear item in my experience. If the motor is ever overheated, they are junk. If you have a bunch of time on the head, they need inspected or replaced. If the engine has seen an over rev (missed gear) toss them.

Look for signs of wear after peak lift on the cam. If the spring is unable to keep up you will see wear where the rocker contacts the came lobe. Also check for wear, dullness where the rocker contacts the valve stem. Also the valve stem should look nice, not sharp, a nice smooth end. If it is sharp it has worn, probably due to the spring unable to control valve motion.

I have had no issues with stock valves. I prefer them. Valve failures are a lot like piston failures. 99% of the time it is tuning issue or assembly issue but nobody wants to blame themselves, so they blame the part.

 

[bastarddsm]

Yeah everything looks good, the valve tips to have a sharp edge to them, but it could be from using the stock springs before.

I sort of feel like the stock valves ought to be pretty good, as they had to last thru the warranty period with god knows what being done to it.