Repair or Replace?

[PaulProe]

I have a Shelby alum block w/ TrickFlow heads in a cobra replica. Valve train uses PRW Stainless Rocker system. All has been well for 650 miles till one cylinder decided not to play

This seems to be a common occurrence with the PRW system. My builder said he'd had excellent results with them so I followed his advice. He, unfortunately, passed away during the pandemic so this fix is going to be on me.

Couple questions

1) any confidence that I could just replace the broken arm and all would be well? The car is not driven that hard, the spring pressure isn't that high, nor is the lift.

2) any guys who have experienced this, did you replace or repair? Anyone have a system their not using that I could by a few rockers?

Suggestions?

Paul

[blykins]

You probably don't want to hear this, but I would just replace them all.  I think it will happen again. 

Back when I first started my business, this was one of the lines that I carried.   I got a lot of complaints from rockers breaking.  I dropped the line.

[jayb]

I got a call from another forum member who is not usually online.  He saw your post and mentioned that he'd had a PRW rocker that broke, and also an adjuster.  He said a call to PRW got him a replacement part in just a few days, all he had to do was send them a picture of the broken part.  In his experience they were really good to deal with, and he didn't mention any further problems.  Might be worth a call to them to see if they would just send you a new one...

[PaulProe]

Jay and Brent,
Thanks for your comments and ideas. I had already sent a post and pictures to PRW, explaining the issue and asking for their input and support.

I guess the two alternatives is to fix the broken one and hope (0-$100, depending on PRW), or replace the system which looks like $1000 rough. Makes for a very difficult decision. Wish the two options were a little closer, financially

Fortunately, the break was clean and it doesn't look like any loose pieces went into the engine. Just wish I had some confidence that there aren't 15 more waiting to do the same thing. I see multiple posts of similar failures and same results. Some replaced just the one and were fine, others replaced the system.

Thanks, going out to look for my crystal ball

Paul

[cjshaker]

If it's a mild cam to begin with, as you stated, what confidence do you have that it won't happen again? I would replace them with something better, even if it's stock stuff, which never break. Next time it may hang open a valve, and that could ruin your day.

[TJ]

Theoretical question for those with more experience than me… How often do rockers break this early on a tame cam without an underlying cause? 

Probably want to look for a cause and verify there’s no further damage. Check for damaged pushrods, lifters etc.  Definitely check both push rods and lifters in the affected cylinder but check rest of them as well.  Make sure the affected valve is at the right height (I.e not bent and hanging open). Look for signs the push rods are rubbing the intake tunnels,  I don’t think you have to run it hard to break stuff if things aren’t right.

[My427stang]

Seems to come up weekly across forums and Facebook.  It'll break again.  You have some money in that engine, I'd put a better set and press on.  What if something bound up and popped a keeper or pieces when through an aftermarket oil pimp pickup? It will sting only once to do it right.

Hang them on the wall, or see if you can replace rockers only with a name brand.  I haven't see a set up close to know rocker width and shaft size, but failures almost always are a split at the bottom of the rocker or an adjuster failing, so I'd likely gamble on reusing the shaft if it was a standard size
. 

[fe468stroker]

There appears to be not much "beef" in the area that broke.  Contact Doug at Precision Oil Pumps about a set of his roller rockers.  Looks like your spacers etc are fine.  With 16 new rockers and your existing hardware, it would really be a small price to pay for peace of mind.  He is a vendor here and a stand up guy.

[Rory428]

Appears to be a nicengine with some good, top quality parts. Do yourself a favor, and get those Chinese bargain basement rockers off of there, before they cause serious damage. Those rockers are notorious for breaking, your engine deserves better rockers.

[1968galaxie]

I believe the PRW aluminum ones are better than the stainless. That being said I would not use PRW rockers on a lawnmower engine.

[allrightmike]

I pulled the PRW rockers out before they gave trouble. Replaced the rockers & shafts with Harland Sharp parts and used the PRW stands and shims (they do have shaft end supports). You may need to re shim your rocker stands to acquire correct rocker geometry. This is cost effective.

[PaulProe]

Thanks for the support, guys, I really appreciate it.

Can anyone tell me more about re-using my existing hardware with new "other brand" rockers? Any experience with re-using the shaft? Harland Sharp vs T&D vs Precision Oil Pumps - is one preferred over the others? Does only one work with existing PRW stands?

Hoping to learn from everyone's experience

[Sand hauler]

Can't go wrong with any of those three, including the one ones from lykins motor sports

[PaulProe]

One last question for the experienced:

The shafts are .840" dia., the same as the HSharp bushed shafts.

So I can use the PRW stands if I choose to use new Harland Sharp rockers and shafts?

The shafts appear to be OK but there is some bushing wear indicated in just 600 miles/21 hrs run time. If I'm going this far, $300 for new shafts might be cheap insurance. I'd also feel a little more comfortable with the sizing between Sharp shafts and Sharp Rockers.

The geometry was pretty good on the last set - if I keep the stands and just change shafts and rockers, what is the probability of the geometry being off. I don't know if the profile of the two brands of rockers is significantly different or not.

Thoughts and Thanks. My local engine builder passed away last winter and I don't have anyone local to bounce these things off of.

Paul

[allrightmike]

PRW stands will fit Harland Sharp rockers and shafts. I believe that I removed a small amount of shim under the stands because the rockers have slightly different architecture. Every setup is different so you must check. If you are able, install two ten lb. springs install two rockers and roll the engine through the valve event to check geometry. Something that I forgot to mention is you may need to change to a shorter pushrod length (as I did). Also you don't want the adjusters in the rockers to extend more than a few threads. Just go step by step.