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just a ski boat with bark
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Discussion Starter #1
I was just wondering if any of you knew what might be causing the strange wear on my exhaust valve spring retainers. It is a steel retainer on a flat tappet cam that started with 145lbs seat and about 375lbs actual open pressure. They were all bought new and the last freshen up they were fine, polished looking surface only.

Things to keep in mind:

• Only the exhaust retainers look like this (intakes look normal)
• I experimented with tighter valve lash (as tight as .024” recommended was .030”)
• It was not coil bound (.180” away from exh and .170” int)


I’m getting to buy new springs and titanium or tool steel retainers so I would like to know what caused this before I buy and install new parts. Is it just wear from a long life? If so why is it only the exhaust retainers when this cam has more lift on the intakes? Anybody have thoughts or ideas for me?



Thanks,
Loren
 

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mo balls than $cents$
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stock heads with stock rotators on the ex spring bottoms?
 

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Making metal for sure > and I bet you could see it in the head where tho oil drain hole is. Do the finger swipe test.
 

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just a ski boat with bark
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Discussion Starter #5 (Edited)
stock heads with stock rotators on the ex spring bottoms?
No the 990s, no exhaust rotators.


Loren....were the locks real tight in there? My first impression is valve float for what ever reason. Have you checked that particular spring pressure since you removed it?
No they they felt fine, no unusual wear between the retainer and lock either. Yes it was probably floating the valves, it was down some rpm at the Ft Cobb race (last time it was ran). Spring pressures are down about 10-12lbs at seat and 20-25lbs open. :))eek:))

Bill I took it apart because I suspected valve float was the cause of my rpm drop. Lash was good as was cranking compression and leak down so I pulled valve springs next and found this.

No wear here that I see
 

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I am surprised they are only down 5 lbs on the seat. I would have guessed much more than that. Welcome to the effects of valve bounce, or harmonics.

Valve float is kind of a misnomer. True float implies the entire valve train became unhinged, and occurs on the start of the closing phase. Loft off the nose occurs more often than float. Float is the result of bad lobe design, of insufficient open pressure, or both, along with heavy ass valves and retainers. Be surprised if this was the case with a solid flat. Not saying it can't. Just less likely than bounce.

Bounce is the result of too fast of a closing ramp and/or weak seat pressure. The fact that you have tightened the lash could have some effect on this, but I would think that it would make the situation better, not worse. If you open the lash, it could sit the valve on the seat during a higher velocity area of the lobe. Most cams slow the velocity down in the final stages of closing the valve.

I am guessing by your posts that this a drag deal, so the Rs aren't held at some continous RPM. Harmonics have a funny way of attacking valve train is certain RPMs and not in others. I have seen valve spraings destroyed at mid range RPM levels in a matter of minutes.

My big question ould be, what do the valve seats look like. That can be very telling. Leak down may not show it, but your seats could be getting pounded as well.



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Were the locks shinny? Was the inside of the retainer shinny?
 

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mo balls than $cents$
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could it not be as simple as the springs didnt wanna rotate against the heads and did it at the retainers instead?
 

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just a ski boat with bark
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Discussion Starter #9 (Edited)
I am surprised they are only down 5 lbs on the seat. I would have guessed much more than that. Welcome to the effects of valve bounce, or harmonics. I'll double check my numbers tonight in case my memory is slipping on the seat pressures. me bad they were 10-12lbs light at seat and 20-25lbs light at open :))eek:))

Valve float is kind of a misnomer. True float implies the entire valve train became unhinged, and occurs on the start of the closing phase. Loft off the nose occurs more often than float. Float is the result of bad lobe design, of insufficient open pressure, or both, along with heavy ass valves and retainers. Be surprised if this was the case with a solid flat. Not saying it can't. Just less likely than bounce.

Bounce is the result of too fast of a closing ramp and/or weak seat pressure. The fact that you have tightened the lash could have some effect on this, but I would think that it would make the situation better, not worse. If you open the lash, it could sit the valve on the seat during a higher velocity area of the lobe. Most cams slow the velocity down in the final stages of closing the valve. This was what I was considering that with the light seat pressure and heavy valve and retainer it was bouncing when they closed.

I am guessing by your posts that this a drag deal, so the Rs aren't held at some continous RPM. Harmonics have a funny way of attacking valve train is certain RPMs and not in others. I have seen valve spraings destroyed at mid range RPM levels in a matter of minutes. This is a dual purpose deal not "race only". It has several more hours cruising and pulling tubes and skis than it does actually making passes.

My big question would be, what do the valve seats look like. That can be very telling. Leak down may not show it, but your seats could be getting pounded as well.no idea the heads are still on the engine at this point
Thanks for all your input.
 

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I was just wondering if any of you knew what might be causing the strange wear on my exhaust valve spring retainers.• Only the exhaust retainers look like this (intakes look normal)


Thanks,
Loren
in the pic this looks like corrosion pitting. Could exhaust gasses escaping up the valve stem do this, or is this just the way they typicaly look when pounded?
 

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Exhaust gases up the stem? Like what, a jet stream approching the speed of sound. Thats a long ways for a exhaust leak past a valve guiude to tear up a retainer that bad.
No, thats just plain ordinary metal fatigue and distress.

I would like to know who made the retainer. Almost looks like the steel wasn't upto the task. But its hard to say. You would think there would also still be signs in the lock area like Chris said.



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were the retainers correct for the valve springs? Same springs & retainers as the intakes?
 

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Exhaust gases up the stem? Like what, a jet stream approching the speed of sound. Thats a long ways for a exhaust leak past a valve guiude to tear up a retainer that bad.
No, thats just plain ordinary metal fatigue and distress.

I would like to know who made the retainer. Almost looks like the steel wasn't upto the task. But its hard to say. You would think there would also still be signs in the lock area like Chris said.
i wasnt thinking of a jet stream, just the presence of contaminants...looks like water corrosion...electrolisys looking maybe. It is the pitting and how the pitting dont have sharp edges that made me say that. Dont look spalled. There is a place on the inner ridge between 5 and 7 that looks funny too...more like wear i would imagine. Now if the part has been brushed, maybe that is why it looks like that.

what do the top of the springs look like?
 

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I noticed the wear your talking about on the raised area for the inner spring. Looks more like you would expect for a spinning spring.i think the outer area with the pits is just metal that fatigued and and the reason it looks smoothed over with no sharp edges is its been worn. I seriously think is corrosion.

I questioned the maker of the retainer because I wonder just how had the retainer is. Like you said, what does the top of the spring look like.

Interesting that this thing has been apart for a freshen upand no sign of this before.
I would still want to go with an unhappy spring/cam combo. Interesting that is not only just on the exhausts, but its on all the exhausts.



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just a ski boat with bark
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Discussion Starter #18
were the retainers correct for the valve springs? Same springs & retainers as the intakes?
It's a Lunati cam with their matching springs, locks and retainers and installed per their specifications.
 

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just a ski boat with bark
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Discussion Starter #19 (Edited)
There is a place on the inner ridge between 5 and 7 that looks funny too...more like wear i would imagine. Now if the part has been brushed, maybe that is why it looks like that.

what do the top of the springs look like?
That area is where the dampener was riding, the top of the springs look normal but the edge of the dampner is worn where it's been hitting the dampener.
a typical intake retainer


all the springs look like this top and bottom
 
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