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Discussion Starter #1
I have a set of losito 9 degree ford billet heads. Bought from Bennett racing. The victory titanium intake valves keep breaking an inch below the retainer. This is now the third time.

I called victory they seem quite interested in helping look at them. The machine shop thinks it was a bad batch of valves or some coinciding harmonic.

It only turns 8-8500 rpm, and happens in less than 15 runs.

I was just curious if anyone else has had valves break an inch down from the retainer?

Any comments on why ?

It has Jessel .927 key way lifters. 3/8 to 7/16 rods TD shafts. Manley next tek springs. 55mm cAm.
 

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Do the springs on the outside diameter touch the head anywhere ?

We had this happen once and it was determined that the springs were rubbing the heads
and side loading the valve.

Jake
 

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when you say / referr to the breakage occurring at an inch below the retainer...does that mean that it is the area inside the valve guide or is it just above where the guide stops. we have seen damage right where the guide stops...........distress... because the geometry was real bad with the roller wheel running off the edge of valvestem and causing great amount of side loading...at maximum lift.....
 

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Man it's like Taboo to even talk about breaking valves.

Check your geometry, check for any kind of rocker arm bind or spring bind or alignment/flatness issue to valve tip.

To say a bad batch? I don't know if that's even possible?
 

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I would look at spring bind first. This seems to be the most common mode.
 

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Discussion Starter #8
Do the springs on the outside diameter touch the head anywhere ?

We had this happen once and it was determined that the springs were rubbing the heads
and side loading the valve.

Jake
I appreciate the info jake, I am going to check. Thank you.
 

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I have a set of losito 9 degree ford billet heads. Bought from Bennett racing. The victory titanium intake valves keep breaking an inch below the retainer. This is now the third time.

I called victory they seem quite interested in helping look at them. The machine shop thinks it was a bad batch of valves or some coinciding harmonic.

It only turns 8-8500 rpm, and happens in less than 15 runs.

I was just curious if anyone else has had valves break an inch down from the retainer?

Any comments on why ?

It has Jessel .927 key way lifters. 3/8 to 7/16 rods TD shafts. Manley next tek springs. 55mm cAm.
What is the distance between the bottom of the retainer and the top of the guide with the valve on the seat?
 

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For as much as Conrad has invested in QC, a bad valve would be the last thing to consider, but if it is wrong, he'll make it right.
 

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especially knowing it has happened 3 times.
Yep, I'm guessing the break point is about at the top of the guide when the valve is seated. I've seen this before when the valve is bouncing at closing. There is enough flex or wobble so that when the next event happens the stem is not it the correct position when the rocker hits it and the side load creates a lot of stress between the stem and the top of the guide. It eventually breaks.

For some reason the seating velocity is to high for the valvetrain/spring combination. That's what I would be looking at in this case.:smt102
 

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What size valve stem is it?
 

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Discussion Starter #16
I think lobes is right. Engine builder measured cam and said it had a lot of jerk so we changed cam and went from triples to double springs. Lost 74 grams per spring and retainer. Will hopefully stay together.
 

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I broke a Ti. Victory valve in 2013 that caused a lot of damage to my motor. I had the exact same set of heads, rockers, etc. for a long time so it was not a new set up nor was anything wrong. We sent the valve to Victory along with a couple others and they said nothing was wrong. I was nervous about not finding something wrong, but the motor has been running fine every since we put it back together.
However, with 3 broken valves I would say something is wrong with the set up as already mentioned.
 

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Discussion Starter #20
I broke a Ti. Victory valve in 2013 that caused a lot of damage to my motor. I had the exact same set of heads, rockers, etc. for a long time so it was not a new set up nor was anything wrong. We sent the valve to Victory along with a couple others and they said nothing was wrong. I was nervous about not finding something wrong, but the motor has been running fine every since we put it back together.
However, with 3 broken valves I would say something is wrong with the set up as already mentioned.


Hopefully I have your luck, breakage gets frustrating.
 
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