PRW/PQ rocker failure

[68cuda408]

So I took the car to E-town Mopar show for the first time. I planned on making some time runs and if all went well park it in the show and make it a day. The first 3 passes in this car since finished netted an 11.4,11.3 and a shut down at 1000' 11.4 . I didn't want to screw up the cars racing in eliminations so I bailed. Granted this is a street car and already has over 1600 miles on it I was very happy. to be told I couldn't race anymore unless I slowed down (no bars). Happy with that great day I loaded up for the 4 hour haul to Lebanon Valley for what appeared to be at least 4 times bigger by attendance. With the same plan hit the staging lanes, did my burnout noticed it seemed a little labored (unusual with EFI)Left at 3k and instantly noticed something wrong. At 50' it started and by 800' I was looking for the turn off. The sickening sound of banging metal. Limped back to the trailer hoping to just keep oil in it.
Took it apart 5 hours later and found this. PRW/PQ rockers both #3 ,#6I and #4E. Hughes Rockers should be here today. 3 damaged valve tips. Anyone see this before? All the rockers failed in the same spot on the same side regardless of position in the engine. The one Rocker not completely broken is cracked from the top towards the roller which would eliminate a geometry/Spring pressure issue. Thoughts?

 

[moparcrazy]

Over Revving ? at what rpm are you shifting, yes its Chinese junk but I've gone 10.36 @ 129 mph in the 1/4 mile and no problems Yet, same junk rockers, ill be changing mine out too Lol.

 

[rumblefish360]

I have only read of failures. This is the first I remember seeing posted. Thank you for that. What are the spring pressures?

 

[qkcuda]

Wow! I bought a set of those years ago, and sent them back because of poor metallurgy in the rollers (pit marks). I ended up with Crane Golds and they have been fine. I am also running beehive springs and a hydraulic roller cam. Which springs are those?

 

[68cuda408]

I have my limiter set at 6500 through the FAST XFI system, It did bounce off it quickly in the water box , Shift point/light is set at 5800. I just can't figure out how the cracks start and open at the top and not at the thin roller end. That's the part the would make me think casting issues. That and they're all cracked on the same side in the same place. Since I never had an issue, I don't know when the damage started, but the evidence shows it was progressing.

 

[68cuda408]

The heads were purchased assembled as part of a "blueprinted" known performance top end. They came with the roller cam and rockers. I did have to change to beehives due to the retainers locking up on the fulcrums. Geometry wasn't the culprit, just clearance. The replacement springs were sent to match the specs of the original

 

[cannucky]

wow whatever did cause it sure seems consistant , I wore the bushings and grooved the shafts on a set without breaking a rocker , also running beehives and a hydraulic roller , I'm using the smaller retainer in mine tho and the fact you had to clearance the springs some might be a part of the problem .

 

[furrystump]

My guess both design and poor metallurgy. The arms down near the roller look thin and unlike others there's no real boss that ties them together.

 

[qkcuda]

My cam is a Comp XR286HR, a bit smaller at 236/242 and 541 lift. My valve springs and retainers are exactly the same as yours.

 

[68cuda408]

well ,if anyone wants to add 4 new ones they can have the set.......

wow whatever did cause it sure seems consistant , I wore the bushings and grooved the shafts on a set without breaking a rocker , also running beehives and a hydraulic roller , I'm using the smaller retainer in mine tho and the fact you had to clearance the springs some might be a part of the problem .

I didn't machine anything I noticed it during assembly and replace the springs before fire up

My cam is a Comp XR286HR, a bit smaller at 236/242 and 541 lift. My valve springs and retainers are exactly the same as yours.

Have you run it yet?

 

[RustyRatRod]

There have been lots of reports of failure........and lots of reports of success. Like rumblefish said, this is the first I can remember anyone posting pictures.

Having even read of the failures is enough for me to save my money. That sucks, but you'll get it back goin again. Looks like it was runnin hard before it happened.

 

[68cuda408]

There have been lots of reports of failure........and lots of reports of success. Like rumblefish said, this is the first I can remember anyone posting pictures.

Having even read of the failures is enough for me to save my money. That sucks, but you'll get it back goin again. Looks like it was runnin hard before it happened.

I felt the same way about reading of failures and not seeing. That's pretty much why I posted and to see if maybe I missed something. But after 1600+ miles and only three and a half trips down the track I would tend to believe its parts failure. The heads should be back before Friday (3 chipped valve tips).A set of Hughes rockers delivered today and another set of custom pushrods should do the trick. So my trip to Maryland Saturday is scrapped....I'll work and pay for this instead.

 

[yellow rose]

You have issues other than a rocker failure.

The fact that you didn't correct the rocker geometry is the first issue I see.
Second is that beehive spring. I drank the beehive cool aid but refuse to use them any more.

That's what valve float looks like. It is partly from geometry not being right, and springs. Before you go any further, you need to get ahold of Mike at B3 racing engines and let him help you. It will be the best money you've ever spent.

There is zero wrong with that rocker.

 

[Bigdummy]

Over Revving ? at what rpm are you shifting, yes its Chinese junk but I've gone 10.36 @ 129 mph in the 1/4 mile and no problems Yet, same junk rockers, ill be changing mine out too Lol.

I've got a friend that's has a FE engine runs 5.55 in the eighth with those rocker arms

 

[MOPAROFFICIAL]

I have 3 sets out there rolling around in northern cal, Denver, and Tenn doing just fine.
Yours look like they're hanging off the valve stem. The rocker hitting the old springs was the indicator of a geometry issue, then the sweep pattern.

 

[Inertia]

If you look at the very first pic, and put a centerline thru the one remaining roller hole and project it to opposite rocker, the center appears low,. To me the whole shaft is low. I believe the geometry is way off, and damage may have been done by roller going "over the edge" or too close to, which would stress rocker tip. Alternative is coil bind at operating temp. jmo.. Regardless, check geometry on new ones.. cheers.

PS. I also have had issues with PRW/PQ rockers on a big block, they went back, and I won't use them again..

 

[jimjimjimmy]

I agree this is more than a rocker failure .

 

[68cuda408]

Thanks for the input. The roller sweep wear is dead center with about .040" untouched top and bottom. The retainer interference wasn't just a little. The rocker shaft couldn't be bolted down. The pic is during assembly with no pushrods. To get the centerline where it needed to be would've needed to be required more spacing than I was comfortable with. With the smaller retainers the centerline was perfect with no shims. I still don't see how upward stress at the pushrod created a downward crack at the top going down towards the valve. Also no bent pushrods.

 

[RAMM]

I agree this is more than a rocker failure .

I'm more amazed that when the one rocker turned into a valve spring compressor it didn't drop a valve!

What I find difficult to explain is the fractures opening near the fulcrum and not propagating from the roller tip. This application is really not a high revving/high stress application. It could be float induced but my first thought is wrong heat treatment, wrong alloy. That being said thanks for posting pics, I've had offshore adjusters fail on me and that was enough to NEVER use any offshore rocker arms again. J.Rob

 

[qkcuda]

well ,if anyone wants to add 4 new ones they can have the set.......

I didn't machine anything I noticed it during assembly and replace the springs before fire up


Have you run it yet?

Yes I have over three years running on that combo.

 

[yellow rose]

Thanks for the input. The roller sweep wear is dead center with about .040" untouched top and bottom. The retainer interference wasn't just a little. The rocker shaft couldn't be bolted down. The pic is during assembly with no pushrods. To get the centerline where it needed to be would've needed to be required more spacing than I was comfortable with. With the smaller retainers the centerline was perfect with no shims. I still don't see how upward stress at the pushrod created a downward crack at the top going down towards the valve. Also no bent pushrods.

View attachment 1715103843

Are you saying you have a .040 wide sweep pattern? Again, you can do what you want but my money is on what I posted earlier. Between the geometry being off and those springs you have other issues.

b3racingengines.com best time and money you can do.

 

[68cuda408]

I'm more amazed that when the one rocker turned into a valve spring compressor it didn't drop a valve!

What I find difficult to explain is the fractures opening near the fulcrum and not propagating from the roller tip. This application is really not a high revving/high stress application. It could be float induced but my first thought is wrong heat treatment, wrong alloy. That being said thanks for posting pics, I've had offshore adjusters fail on me and that was enough to NEVER use any offshore rocker arms again. J.Rob

This was my main concern, I understand that if in fact the roller slid inward off the valve tip and jammed, breakage would be inevitable (and would've started at the thin part of the roller) and this post/question would've been different. The stress fractures seem contradictory to geometry failure though its easy to blame. Also the broken rocker didn't hold the valve open, just beat the hell out of the stem.

 

[AJ/FormS]

I have seen cracks open up like that on other types of failures, not rocker-arms.
My theory was that the repeated hammering and bounce-back just leaves the crack hung open.

Consider how many times those arms were activated;
Say average 5000 rpm for 7 seconds; that's 292 bashings. That's a whole lotta pounding. And that was just the last run.

 

[68cuda408]

Are you saying you have a .040 wide sweep pattern? Again, you can do what you want but my money is on what I posted earlier. Between the geometry being off and those springs you have other issues.

b3racingengines.com best time and money you can do.

No It's about .040" untouched top and bottom.it was the first thing I checked after I took it apart. The heads are already at the machine shop getting checked and 3 valves, so I can't get pics till Friday. As far as B3, let me get all my stuff in hand before I get involved in that.Thanks

 

[MOPAROFFICIAL]

Thanks for the input. The roller sweep wear is dead center with about .040" untouched top and bottom. The retainer interference wasn't just a little. The rocker shaft couldn't be bolted down. The pic is during assembly with no pushrods. To get the centerline where it needed to be would've needed to be required more spacing than I was comfortable with. With the smaller retainers the centerline was perfect with no shims. I still don't see how upward stress at the pushrod created a downward crack at the top going down towards the valve. Also no bent pushrods.

View attachment 1715103843

But what's it look like at mid and full lift?

Upward stress , must have hit your valve covers lol ;)

Notice how theu all cracked on one side, coincidence?
Crooked something going on, stands, guides, that's telling of either that or they just plain seconds with flaws.