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Discussion Starter #1
What's up guys,

Looking for a little bit of insight from those with much more knowledge than I that I found while tearing down my fiance's sedan. During winter mods, we pulled her Ported LSA Heads, stock valves, BTR Upgraded springs/retainers/etc in favor of some new GenX Ported Trickflows. All seemed well before tear down, no valve train noise, nothing seemed out of the normal, just some typical winter upgrades.

Long story short, we sold her heads to a guy out of state, who, when dropped off to his builder for assembly, noted that the exhaust valves "were toast and needed to be replaced". Further stated that "tip of the valve stem in the middle is not smooth and flat, it has a rounded concave groove in them, the rocker arm is what causes this". That being said, I split the cost with him on new exhaust valves and all is well with him.

These are the pictures he send of the exhaust valve tips on the head, along with the rockers laid out from the drivers side front to back.












I guess I have a few questions at this point.

-Should I be concerned that something could be wrong with the valve train moving forward? The valves on her old heads were OEM, ~91,000mi valves

-Is wear like this typical over time? Top end combo was BTR Stage 2, Johnson 2110's, 7.4" BTR Pushrods, OEM Rockers with Straub Trunions, BTR Springs with Titanium retainers.

-Can the rockers be reused or should we buy OEM Replacements? Is there a better aftermarket replacement?

We'll be measuring for pushrod length with the new Trickflows so I want to make sure everything else is right before we button the motor back up.

Thanks in advance!
 

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From my phone I'd say the rockers look good.

My uneducated opinion on the valves is that they look pretty normal for a 90+k mile set of heads with an aftermarket cam... that has aggressive lobes, high lift, and probably some valve float at higher RPM mixed in with less than ideal geometry.

What was the redline? It looks like the valves were floating a bit which suggests being undersprung for the RPM.

But that's my novice take!

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Discussion Starter #3
From my phone I'd say the rockers look good.

My uneducated opinion on the valves is that they look pretty normal for a 90+k mile set of heads with an aftermarket cam... that has aggressive lobes, high lift, and probably some valve float at higher RPM mixed in with less than ideal geometry.

What was the redline? It looks like the valves were floating a bit which suggests being undersprung for the RPM.

But that's my novice take!

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I'll have to look back at what shift point was set at in the tune, I don't beat on the car when I drive it so I never really pay attention at where it's winding out too. I know the dyno pull was ran out to ~6,400-6,500 so I can't imagine it was any higher than that.
 

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Discussion Starter #5
I would suspect preload.
Is it strange that it was only noticed on the exhaust side versus all over if the pushrod length was all the same? Or is that indication that the exhaust side should of had a different length pushrod?
 

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Are the lifters good? I did that to an ls1 that had bad lifters, didn't take 90k miles though, haha. The rocker arm is what is physically wearing the valve, but it is not likely the root cause. Aggressive cams and high rpms will beat the valve tops.
 

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Is it strange that it was only noticed on the exhaust side versus all over if the pushrod length was all the same? Or is that indication that the exhaust side should of had a different length pushrod?

Not really if you take into account the difference in intake and exhaust lobes used on the BTR 2 cam along with using a lifter with a different spec then a stock GM lifter.
 

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Discussion Starter #8
Are the lifters good? I did that to an ls1 that had bad lifters, didn't take 90k miles though, haha. The rocker arm is what is physically wearing the valve, but it is not likely the root cause. Aggressive cams and high rpms will beat the valve tops.
I'd hope so, they were brand new Johnson 2110's put in with the cam swap less than 3,000 miles prior to the head upgrade.

Not really if you take into account the difference in intake and exhaust lobes used on the BTR 2 cam along with using a lifter with a different spec then a stock GM lifter.
Fair enough, I'll chalk this one up to ignorance in valve train geometry for the combo.
 

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I'd hope so, they were brand new Johnson 2110's put in with the cam swap less than 3,000 miles prior to the head upgrade.



Fair enough, I'll chalk this one up to ignorance in valve train geometry for the combo.
Matt has already responded with good info, so I will attempt to add to Matt's comments:

For these engines and street use the 'Mid Lift' method by Miller, works the best
regarding valve train / rocker arm geometry.

Also, the quality of the oil, especially it's ability to work under
higher then normal temperatures has an impact, more so on
the exhaust side then on the intake side.

Slow exhaust valve opening rates / velocities also add to the heat issue.
This issue relates to 'Heat divided by Time' during the 'Blow down Event.'

However, opening the exhaust valve slower then the intake (as a general reference)
can also provide more power, if the engine is equipped with an open header,
as well as a positive overlap period.

On our engines we would be interested in the differential pressure / the drop in pressure,
as measured at the TB Inlet, versus the Tailpipe.

Cheers
 
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Having been an engine machinist in a previous life I would say that the amount of wear you are seeing on these valves is likely due to the high spring pressures of the aftermarket pieces. There may have also been some preload issues, as others have stated as well, that didn't help the situation. Unfortunately this is often just the reality of running an aggressive cam setup; great performance but it'll abuse the heck out of the valvetrain.

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