Stainless, Bushed PRW Rocker Arms

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mopowers said:
Mine aren't grooved either and my PRW rockers are going on 8-9 yrs or there abouts without an issue whatsoever. I was just asking because if it was so necessary as stated in post #52 by Rat Bastid, why are there so many folks who haven't had a problem running the stainless PRW rockers without grooved shafts (myself included)? And why does B3 sells them if grooved shafts were needed?
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Just curious, how many miles have you put on yours in that time?
 
mopowers said:
Mine aren't grooved either and my PRW rockers are going on 8-9 yrs or there abouts without an issue whatsoever. I was just asking because if it was so necessary as stated in post #52 by Rat Bastid, why are there so many folks who haven't had a problem running the stainless PRW rockers without grooved shafts (myself included)? And why does B3 sells them if grooved shafts were needed?
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I can tell you why I have not done the banana grooves on my shafts yet.

Because (for whatever reason) PRW uses two bushings of which the total width is less than the total width of the rocker body there is a gap between the two bushings and that’s where the adjusters and the oil hole at the top of the rocker get its oil.

If they used a full width bushing like RAU does then I’d groove them.

I suppose PRW does it that way because it’s cheaper. You give up some bearing area but so far I haven’t had that be an issue.

Yet.
 
Newbomb Turk said:
I can tell you why I have not done the banana grooves on my shafts yet.

Because (for whatever reason) PRW uses two bushings of which the total width is less than the total width of the rocker body there is a gap between the two bushings and that’s where the adjusters and the oil hole at the top of the rocker get its oil.

If they used a full width bushing like RAU does then I’d groove them.

I suppose PRW does it that way because it’s cheaper. You give up some bearing area but so far I haven’t had that be an issue.

Yet.
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Thanks for the insight. What's interesting is I have two sets of PRW stainless rockers. One set has the one-piece bushing and the other has two with the gap in the middle. That must've been one of the changes you referred to. I believe the newer one has the single wide bushing, but I could be wrong.
 
mopowers said:
Thanks for the insight. What's interesting is I have two sets of PRW stainless rockers. One set has the one-piece bushing and the other has two with the gap in the middle. That must've been one of the changes you referred to. I believe the newer one has the single wide bushing, but I could be wrong.
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That very well could be one of the changes they made and if they did that good on them because IMO that’s a real nice upgrade.
 
CRUZE 418 said:
The PRW rockers are more or less a complete roller rocker kit. Mike doesn't do anything to them, he just adds a small correction kit for the geometry on the trick flow heads. So the kit is rockers, spacers and shims to center the rockers and non banana groove shafts.
I did not groove my shafts. It's been 3 or 4 years, not saying not to have that done, or get them.
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He does a little work to the shafts so the retaining bolts will fit with the relocation.
 
Wasn’t it (the necessity for a banana groove in the shaft) a hydraulic vs solid cam thing? With a hydraulic the rocker is never unloaded and therefore doesn’t get oil without a banana groove whereas a solid oils during lash? Seems like I read that here a while back and it made sense to me.
 
TT5.9mag said:
Wasn’t it (the necessity for a banana groove in the shaft) a hydraulic vs solid cam thing? With a hydraulic the rocker is never unloaded and therefore doesn’t get oil without a banana groove whereas a solid oils during lash? Seems like I read that here a while back and it made sense to me.
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Makes sense to me too.
Although I have a set of factory 273 rocker arms and shafts that came with banana grooves and a solid cam.
Like you said a hydraulic cam is always loaded, that extra oil groove has got to help.
I think they are a good idea with Hyd. Or Solid.
Unless I'm missing something
I don't see a down side.
 
Mopar69gts said:
Makes sense to me too.
Although I have a set of factory 273 rocker arms and shafts that came with banana grooves and a solid cam.
Like you said a hydraulic cam is always loaded, that extra oil groove has got to help.
I think they are a good idea with Hyd. Or Solid.
Unless I'm missing something
I don't see a down side.
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The only down side would be that PRW doesn't use gooves on their shaft necessitating the expense of purchasing shafts that do have grooves.
And of course when you do this, it gives them the right to deny any potential warranty claims because you didn't use their shafts.
 
Newbomb Turk said:
That very well could be one of the changes they made and if they did that good on them because IMO that’s a real nice upgrade.
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I'm pretty sure we went through this before early on in this thread.
 
I am not sure about that hydraulic vs solid, loaded vs unloaded argument. It sounds logical, and i don't have the math skills to prove otherwise, but it would seem a random valve lash number like, .020 plus .004 for (.024) expansion would represent a very small number of degrees of rotation it would be unloaded and getting oil.
I would say on the hydraulic side being always loaded, i could see the lifter plunger acting somewhat like a shock absorber with small deflections or bounce partially unloading it also.
Again, above my paygrade
 
TT5.9mag said:
Wasn’t it (the necessity for a banana groove in the shaft) a hydraulic vs solid cam thing? With a hydraulic the rocker is never unloaded and therefore doesn’t get oil without a banana groove whereas a solid oils during lash
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I don't see this as a logical reason needing a groove for hydraulic vs solid.
There are some generic shafts out there that have the oil holes located wrong and not centered in the rocker, pretty much outside the bushing area.
 
I don't think that solid or hydraulic dictate whether grooves are needed. The rocker is always riding on a film of oil, otherwise the system fails. I don't see how either one can be substantially better at getting oil to the interface, especially when you consider the time available to move the oil. The truth of the matter is that the groove distributes oil more evenly across the rocker so that the oil film has a better chance of standing up to the load. Just about every plain bearing application I've ever run across in industry ( punch presses, lathe and mill spindles, linear slides, etc ) all have grooves machined across the inner face of the bearing to distribute the oil. It may even be more critical in a system with reciprocal motion like the valve train, than a rotary one. I am not debating whether a plain bearing without grooves can work in a given application, but I will guarantee you that the one that has proper distribution grooves in the bearing will outlast the other one ten out of ten times.
I've got a set of PRW 1.6 rockers that will be going in this summer (hopefully). I've cleaned a ton of crap out of the passages, chased all the threads, and will be grinding grooves into the shafts before they are installed. I can't remember if mine are one or two piece bushings, but in my mind the two piece is a better design because it is has a larger available volume of oil available local to the wear interface. May not make a significant difference but it can't be a bad thing.
 
olei said:
What valve spring pressure are you running?
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I don't have it at the top of my head, but that engine runs the beehive equivalent to the comp 995 springs w/ 0.560" valve lift. By my math, that should put it around 340lb open, so not a ton. The PRW rockers have been fine though with this combo.
 
gzig5 said:
I don't think that solid or hydraulic dictate whether grooves are needed. The rocker is always riding on a film of oil, otherwise the system fails. I don't see how either one can be substantially better at getting oil to the interface, especially when you consider the time available to move the oil. The truth of the matter is that the groove distributes oil more evenly across the rocker so that the oil film has a better chance of standing up to the load. Just about every plain bearing application I've ever run across in industry ( punch presses, lathe and mill spindles, linear slides, etc ) all have grooves machined across the inner face of the bearing to distribute the oil. It may even be more critical in a system with reciprocal motion like the valve train, than a rotary one. I am not debating whether a plain bearing without grooves can work in a given application, but I will guarantee you that the one that has proper distribution grooves in the bearing will outlast the other one ten out of ten times.
I've got a set of PRW 1.6 rockers that will be going in this summer (hopefully). I've cleaned a ton of crap out of the passages, chased all the threads, and will be grinding grooves into the shafts before they are installed. I can't remember if mine are one or two piece bushings, but in my mind the two piece is a better design because it is has a larger available volume of oil available local to the wear interface. May not make a significant difference but it can't be a bad thing.
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I forget who made that argument but it seemed logical to me. I tend to agree with you and I’ll also add that the oil distribution HAS to also be a function of oil pressure at the interface as well. 5 psi obviously won’t move as much oil as 40 psi through a fixed orifice.
 
TT5.9mag said:
I forget who made that argument but it seemed logical to me. I tend to agree with you and I’ll also add that the oil distribution HAS to also be a function of oil pressure at the interface as well. 5 psi obviously won’t move as much oil as 40 psi through a fixed orifice.
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If it’s hydraulic lifters I always groove the shafts.

There is never any clearance between the rocker and the shaft.

I’ve seen more trashed rockers from hydraulic lifters and no grooves in the shaft than any other thing I can think of.
 
Newbomb Turk said:
If it’s hydraulic lifters I always groove the shafts.

There is never any clearance between the rocker and the shaft.

I’ve seen more trashed rockers from hydraulic lifters and no grooves in the shaft than any other thing I can think of.
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You might be the one I originally heard it from and why I gave so much credit to it.
 
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