PRW/PQ rocker failure

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The fact that they broke in the same place on the same side was suspect. Especially since it was 2 on each bank.The wear pattern I saw on the valve tips would say they were hitting flat.As far as being skewed over the valve,it doesn't look that way, but shouldn't affect the valve side of the fulcrum if landing flat on the tip.
 
This guy ran stainless in a BBC in a boat, 7k all day......."Crower Enduro S/S rockers, ran for 2.5 seasons, 1 broken rocker at about 1.5 seasons, lash 'moving around' a bit. At 2.5 seasons, 8 yes 8 cracked rockers 5 x exhaust, 3 x inlet. They were all cracked were the roller fork meets the trunnion boss, the cracks were on the top side indicating a flexindg under pressure of the rocker."...Sound the same? Only way I could imagine the tops being stressed like that would be to have the roller roll off the valve tip at full compression (float) and the valve then exerting pressure on the top during the very first part of the rebound. Maybe lash caps?
 
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Do PRW rockers have a lifetime warranty? Saw that somewhere too.
 
Kinda',though the boat ran longer and harder. The end result would seem the same
 
pishta said:
Do PRW rockers have a lifetime warranty? Saw that somewhere too.
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The builder that sold them to me with the top end components offered to take care of it for me,but I opted to switch brands. I'm sure that these probably work fine for most applications and mine isn't that special. They just failed on me, the two years I've been using them have been eventless, yet something changed or slowly developed. When this happened I recalled the complaints and chose to switch.
 
I'm with the "geometry is off" group. They broke for a reason, and metallurgy or country of origin ain't it. First giveaway to me would have been the spring contact issue. If you have .040 on each side, the sweep is too wide. Rough guess - you should have .100"+ on each side give or take.
 
moper said:
I'm with the "geometry is off" group. They broke for a reason, and metallurgy or country of origin ain't it. First giveaway to me would have been the spring contact issue. If you have .040 on each side, the sweep is too wide. Rough guess - you should have .100"+ on each side give or take.
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You, as well as others, are correct. There is a major geometry problem. The .100" per side would be be a drastic improvement over what it is now, but my calculations show it being more like .155" per side. The sweep pattern with the PRW rockers and the valve lift on the posted cam card, should only be .030" wide.

All the talk of "junk" rockers is a disservice to a part that wasn't properly set up. The Hughes rockers won't be right either, unless the effort is put into installing them correctly. In my opinion, going to that ball style adjuster is a move in the wrong direction. They PRW rocker has better pushrod side geometry, and if PRW gives you the heebee geebees, then a Comp steel rocker would be the next logical choice. Now, if someone could just get them to offer more than just a 1.5 ratio, maybe I wouldn't run so many PRW steel rockers, without failure, btw.
 
B3RE said:
You, as well as others, are correct. There is a major geometry problem. The .100" per side would be be a drastic improvement over what it is now, but my calculations show it being more like .155" per side. The sweep pattern with the PRW rockers and the valve lift on the posted cam card, should only be .030" wide.

All the talk of "junk" rockers is a disservice to a part that wasn't properly set up. The Hughes rockers won't be right either, unless the effort is put into installing them correctly. In my opinion, going to that ball style adjuster is a move in the wrong direction. They PRW rocker has better pushrod side geometry, and if PRW gives you the heebee geebees, then a Comp steel rocker would be the next logical choice. Now, if someone could just get them to offer more than just a 1.5 ratio, maybe I wouldn't run so many PRW steel rockers, without failure, btw.
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There, the EXPERT has spoken. Failure to let him help you (and that includes everyone who runs Chrysler shaft rockers with any aftermarket parts who is reading this thread) will result in piss poor performance, less than max RPM performance and broken parts that shouldn't be broken.

Ignore his expert advice at your own peril.











BTW, I use his stuff and pay for it, gladly. I don't get a thing for telling people to listen to him. He's not that kind of guy. Since I am constantly telling people to patronize him I want everyone to know its from using his stuff and it working.
 
68cuda408 said:
The builder that sold them to me with the top end components offered to take care of it for me,but I opted to switch brands. I'm sure that these probably work fine for most applications and mine isn't that special. They just failed on me, the two years I've been using them have been eventless, yet something changed or slowly developed. When this happened I recalled the complaints and chose to switch.
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There is a thread here somewhere where it was an established fact that there was a run of those rockers improperly machined and the roller did not sit square on the tip
of the valve stems. If so, all of the load would be applied to only one side of the roller axle, this would double the stress on the arm "blade" on that side & cause the arm
to twist. That is a sure fatigue perscription for a failure in a high load/cyclic rate application.
 
Killer6 said:
There is a thread here somewhere where it was an established fact that there was a run of those rockers improperly machined and the roller did not sit square on the tip
of the valve stems. If so, all of the load would be applied to only one side of the roller axle, this would double the stress on the arm "blade" on that side & cause the arm
to twist. That is a sure fatigue perscription for a failure in a high load/cyclic rate application.
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Post #26
 
B3RE said:
Post #26
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True, however if the amount is slight enough and the OP was checking with the actual springs & not checking springs, the roller may still put down a full pattern if the
rocker is twisting under load. Just sitting there w/o a load on them a feeler would easily verify/discount this by checking both sides of the roller held down by hand.
Not as likely(maybe), the guides aren't square to the shaft, and no fault of the
rockers.
 
Killer6 said:
There is a thread here somewhere where it was an established fact that there was a run of those rockers improperly machined and the roller did not sit square on the tip
of the valve stems. If so, all of the load would be applied to only one side of the roller axle, this would double the stress on the arm "blade" on that side & cause the arm
to twist. That is a sure fatigue perscription for a failure in a high load/cyclic rate application.
Click to expand...
I am not an expert, but agree w/ this post. Was also wondering if the guide and valve job could be off angle , creating the same situation . ??????????
 
I appreciate all the feedback, and expert advise. Since starting over I will again be doing the geometry process. For the record and according to the 8 page setup instructions that came with the new setup, my roller wipe pattern, (that was evident on the non damaged valve stems) was in spec with approximately .040"+ untouched top and bottom (looking at the valve stem). I will now however have to contact Hughes for an "adjustable lifter tool" to replicate their roller lifters for set up. Their 8 pages of instructions are exactly as B3RE has stated but also reassure me of my previous set up. I did not use checking springs during the first assembly (very interesting idea on non square rollers), after reading all the responses and the new instructions, this will be done too. As for the guide straightness, that's why both heads are at the machine shop being checked. Thank you all again.
 
68cuda408 said:
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?

View attachment 1715103735

View attachment 1715103736
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If I could ask please what type of hold down is that on the rocker shafts? I can see the rocker shaft exposed through the shims on the left rocker in the picture. I think all the experts that gave opinions are all correct but it appears to be a combination of mechanical problems that may be compounded by metallurgy problems. I'm not sure whose heads those are but the first thing to check while they're apart is the rocker arm shaft bosses to be sure all are the exact same height as most offshore heads aren't. Also check that the centerline of the bosses are parallel to the centerline of the valve stems. As mentioned valve float in combination with the poor geometry between the shafts, rockers and valves coupled with the lateral movement of the rocker arm on the shaft at high rpm and possible poor machining of the rocker arm bores all added to the failure.
 
Edelbrock performers with the steel PRW/PQ holdowns that came with the kit. The exposed shaft is mostly a reflection, There are 3 different shim materials and the thinnest is shiny spring steel. The roller tips have/had full coverage on the stems.


75Sport said:
If I could ask please what type of hold down is that on the rocker shafts? I can see the rocker shaft exposed through the shims on the left rocker in the picture. I think all the experts that gave opinions are all correct but it appears to be a combination of mechanical problems that may be compounded by metallurgy problems. I'm not sure whose heads those are but the first thing to check while they're apart is the rocker arm shaft bosses to be sure all are the exact same height as most offshore heads aren't. Also check that the centerline of the bosses are parallel to the centerline of the valve stems. As mentioned valve float in combination with the poor geometry between the shafts, rockers and valves coupled with the lateral movement of the rocker arm on the shaft at high rpm and possible poor machining of the rocker arm bores all added to the failure.
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68cuda408 said:
Edelbrock performers with the steel PRW/PQ holdowns that came with the kit. The exposed shaft is mostly a reflection, There are 3 different shim materials and the thinnest is shiny spring steel. The roller tips have/had full coverage on the stems.
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Thank you.
 
Killer6 said:
True, however if the amount is slight enough and the OP was checking with the actual springs & not checking springs, the roller may still put down a full pattern if the
rocker is twisting under load. Just sitting there w/o a load on them a feeler would easily verify/discount this by checking both sides of the roller held down by hand.
Not as likely(maybe), the guides aren't square to the shaft, and no fault of the
rockers.
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I agree, but the OP should then be looking for unusual bushing wear, because the twist you mentioned would also be unevenly wearing the bushing. The fact is, the geometry is off, no surprise that parts are broken, and speculation of other problems without any evidence given from the OP, isn't helping him solve the problem. I'm sorry if that sounds harsh, but I approach problems with pure, simple, factual logic to keep from getting lost in the what ifs. If the bushing wear is evident, then the failure was made at installation, because the parts involved were not checked thoroughly. Do we not all check our bearing clearances, and not just take the crankshaft, bearing, machinists etc. word for it?
 
The current ID on the failed rockers is.874" on both sides and are not out of round. Again, this engine has over 1600 miles on it, 2 seasons of driving and was apart in January when I replaced the Crane retro roller lifters for the Hughes. I had 1 lifter that came up to high in its bore and bled out. New pushrods and no problems. Most of the 1600 miles has been this summer. The "harshness" doesn't bother me at all, I asked if anyone had seen this , got a lot of informative answers, and will be starting again from scratch with a new understanding. Again....thank you
 
68cuda408 said:
The current ID on the failed rockers is.874" on both sides and are not out of round. Again, this engine has over 1600 miles on it, 2 seasons of driving and was apart in January when I replaced the Crane retro roller lifters for the Hughes. I had 1 lifter that came up to high in its bore and bled out. New pushrods and no problems. Most of the 1600 miles has been this summer. The "harshness" doesn't bother me at all, I asked if anyone had seen this , got a lot of informative answers, and will be starting again from scratch with a new understanding. Again....thank you
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If Hughes doesn't say in their directions that the sweep pattern should only be .060 wide at the most, they don't know what they are talking about. I don't care if the pattern is center or not (should be close) but the big deal is how wide the sweep is. I'd have to go look at my notes, but with a PRW 1.6 rocker, about .075 longer installed height and netting .600 lift with a solid FT cam my sweep was .045 and slightly inboard IIRC. That is using a B3 kit. Without it, I would have had to either machine the crap out of the rocker (which is wrong in 99% of builds) or use a beehive spring. I've already said my piece on beehive springs.

The correct way to do it is to correct the geometry. And you just can't raise the shaft. You also have to move the shaft away from the valve.
 
68cuda408 said:
here it is...
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I can only read the one page that shows the .040 number so I can't comment on what the rest of it says but I will say Hughes is full of ****. I'm not the sharpest tool in the shed but I can do simple math, and I'll post it here so anyone who comes along can see what's wrong.

Hughes says the sweep pattern needs to show .040 on each edge of the valve not being rolled on by the roller. Sooooooooo, if you have a 3/8th stem valve this is the math.

.372-.040-040= .292!!!

That is a sweep of .292 thousandths. That's crazy. Beyond crazy.

If you happen to run an 11/32 valve (.342) here is the math.

.342-.040-.040= .262 sweep without correcting geometry. That's insane. You still have the same sweep, but it can't be, because you didn't make the sweep change! Just by going to a smaller valve, you have the exact same sweep, but you can't get .040 from the edges. It's impossible. The sweep is the same but the valve is smaller. In reality in this scenario, you still have the exact same sweep, but instead of having .040 from each edge, you will have only .025 per side. Am I the only one who sees how crazy this is?

Again, what if you have 5/16 stems (I use a lot of them...and the magnum junk comes with 8mm [~.317-318 diameter] so it's not uncommon)? The numbers are even more bizarre.

.311-.040-.040=.231 and yet nothing was changed! That's crazy. Again, in reality the sweep is still .292 you just have even less valve at the edge. You would be .008 from each edge with 5/16 valves.

This isn't to embarrass anyone, or make fun of what is published but that method is as ignorant as it is wrong. You need to know how wide the SWEEP is, not how much valve there is not covered by the sweep pattern. Sooooooo.....

I have a sweep of .045 on a .372 valve. Simple math says I have .163 from the edge on each side, if the sweep is centered.

I'm going to say Hughes is wrong and they should update their tech or stop publishing it. They are responsible for making people ignorant.

Hope that's not too harsh. But fact is fact. You have geometry issues. A sweep that wide is death on parts.
 
yellow rose said:
I can only read the one page that shows the .040 number so I can't comment on what the rest of it says but I will say Hughes is full of ****. I'm not the sharpest tool in the shed but I can do simple math, and I'll post it here so anyone who comes along can see what's wrong.

Hughes says the sweep pattern needs to show .040 on each edge of the valve not being rolled on by the roller. Sooooooooo, if you have a 3/8th stem valve this is the math.

.372-.040-040= .292!!!

That is a sweep of .292 thousandths. That's crazy. Beyond crazy.

If you happen to run an 11/32 valve (.342) here is the math.

.342-.040-.040= .262 sweep without correcting geometry. That's insane. You still have the same sweep, but it can't be, because you didn't make the sweep change! Just by going to a smaller valve, you have the exact same sweep, but you can't get .040 from the edges. It's impossible. The sweep is the same but the valve is smaller. In reality in this scenario, you still have the exact same sweep, but instead of having .040 from each edge, you will have only .025 per side. Am I the only one who sees how crazy this is?

Again, what if you have 5/16 stems (I use a lot of them...and the magnum junk comes with 8mm [~.317-318 diameter] so it's not uncommon)? The numbers are even more bizarre.

.311-.040-.040=.231 and yet nothing was changed! That's crazy. Again, in reality the sweep is still .292 you just have even less valve at the edge. You would be .008 from each edge with 5/16 valves.

This isn't to embarrass anyone, or make fun of what is published but that method is as ignorant as it is wrong. You need to know how wide the SWEEP is, not how much valve there is not covered by the sweep pattern. Sooooooo.....

I have a sweep of .045 on a .372 valve. Simple math says I have .163 from the edge on each side, if the sweep is centered.

I'm going to say Hughes is wrong and they should update their tech or stop publishing it. They are responsible for making people ignorant.

Hope that's not too harsh. But fact is fact. You have geometry issues. A sweep that wide is death on parts.
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Couldnt agree more. I have learned over the years to take Hughes info/ flow numbers, etc, not seriously. I avoid them.
 
68cuda408 said:
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
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All,

I had the same interference with my Comp Retainers and PRW SS rockers. My guy did some grinding to get correct clearance. The PRW rockers came ground some but not nearly enough. I have only a few hundie miles on it and only spun to 5k a few time so far.

Marion
 
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