PRW/PQ rocker failure

[yellow rose]

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

Then I suggest you stop now and correct your geometry before going any further and save yourself some grief.

 

[AJ/FormS]

My rockers are 1.6 ratio, aluminum, anodized Blue,not bushed,roller tips only, and were purchased from my local Mopar dealer in about 1999, right out of the performance catalog; Are they any good?
IDK but they've got about 100,000 miles on now......And every time I go anywhere, they'll be worked.........for sure.
It's very sad for me to read about all these troubles.

 

[mario03srt]

Then I suggest you stop now and correct your geometry before going any further and save yourself some grief.

Yellow,

That was before the builder put together the top end. I'm a novice at this level of detail on valve train. Why should it be redone now? We talked shim if I recall but went the remove some material route. I did not go the beehive route either.


Thanks,
Marion

 

[B3RE]

here it is...

There is so much bad information in that one page, that it's no wonder Mopar valvetrains are so problematic. Centered sweep....wrong, adjust pushrod for max lift....wrong, etc., etc. There is a real misunderstanding of what rocker geometry is, and this kind of information perpetuates that misunderstanding.

 

[B3RE]

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

I've made the point many times, that I have never had to clearance a rocker for spring/retainer clearance when the geometry was correct. There is room for a 1.500"+ diameter spring on a small block with the PRW steel rockers.

 

[B3RE]

My rockers are 1.6 ratio, aluminum, anodized Blue,not bushed,roller tips only, and were purchased from my local Mopar dealer in about 1999, right out of the performance catalog; Are they any good?
IDK but they've got about 100,000 miles on now......And every time I go anywhere, they'll be worked.........for sure.
It's very sad for me to read about all these troubles.

Wrong premise AJ. Not are the rockers any good, but is the installed geometry any good. The point here is that the rocker itself is not the problem, or at least not the major problem. Some designs are a little better than others.

 

[AJ/FormS]

Wrong premise AJ. Not are the rockers any good, but is the installed geometry any good. The point here is that the rocker itself is not the problem, or at least not the major problem. Some designs are a little better than others.

Thanks man, that was the point I was kindof alluding to.
If you get it right, it will go 7000rpm many times a day for many miles and many years,lol. And I'm not saying that I did get it perfect, but the hours and miles seem to indicate that it must be pretty close.
The original assembly was in 1999, so I guess she'll want a freshening one of these days...............If that happens,lol,I guess we'll see. And if it ain't perfect, you'll be the first guy I'll call. Maybe there's a few more horsepower hiding in the old girl. You think enough to drop one camsize?,lol; I sure liked the 223@.050 that I once ran. Just kidding, last time out she went 93 in the 1/8th at 3467 pounds, and I'm not sure I could give that up.......

 

[B3RE]

Thanks man, that was the point I was kindof alluding to.
If you get it right, it will go 7000rpm many times a day for many miles and many years,lol. And I'm not saying that I did get it perfect, but the hours and miles seem to indicate that it must be pretty close.
The original assembly was in 1999, so I guess she'll want a freshening one of these days...............If that happens,lol,I guess we'll see. And if it ain't perfect, you'll be the first guy I'll call. Maybe there's a few more horsepower hiding in the old girl. You think enough to drop one camsize?,lol; I sure liked the 223@.050 that I once ran. Just kidding, last time out she went 93 in the 1/8th at 3467 pounds, and I'm not sure I could give that up.......

Well, I've seen more than a few Mopar running huge cams and laying down early because the geometry was off. The area under the curve of a smaller cam with good geometry is better than a bigger cam with poor geometry. Great power with good driveabilty. What's not to like?

 

[yellow rose]

Yellow,

That was before the builder put together the top end. I'm a novice at this level of detail on valve train. Why should it be redone now? We talked shim if I recall but went the remove some material route. I did not go the beehive route either.


Thanks,
Marion

Because even though the spring isn't hitting the rocker the geometry IS wrong. It's actually a really simple fix. You can do it in the car with a couple of measurement.

You now know it's wrong. It has to be. So fix it. And then go show the engine builder so he stops grinding on rocker arms for no reason.

 

[IQ52]

There is so much bad information in that one page, that it's no wonder Mopar valvetrains are so problematic. Centered sweep....wrong, adjust pushrod for max lift....wrong, etc., etc. There is a real misunderstanding of what rocker geometry is, and this kind of information perpetuates that misunderstanding.

I quite agree. This is one of the reason I'm quitting building engines for others. I'm tired of fighting bad information. Too many times, in fighting the good fight, I'm told how wrong I am by referring me to some BS on Hughes Engines web site.

If Hughes Engines says it, it's gotta be right! Right?

And.......How many times have you heard, that to get the geometry right you change the pushrods on a MOPAR shaft rocker system? When in reality you can remove the pushrod and throw it 150 yards out into a field and the geometry hasn't changed one bit.

I too like the cup adjusters up into the rocker body that get rid of the excessive angle between the ball adjusters and the pushrods with the cup.

I'm doing my first set of EQ Magnum heads. With the valve lift, stem lengths and rocker arms chosen, I've had to do some moving of the rocker studs away from the valve tip towards the intake manifold. Thank God for the vertical mill.

 

[B3RE]

Jim,
I love your knack for taking sarcasm and humor, and rolling it into a warm fuzzy little ball, lol. Well said!

 

[yellow rose]

I quite agree. This is one of the reason I'm quitting building engines for others. I'm tired of fighting bad information. Too many times, in fighting the good fight, I'm told how wrong I am by referring me to some BS on Hughes Engines web site.

If Hughes Engines says it, it's gotta be right! Right?

And.......How many times have you heard, that to get the geometry right you change the pushrods on a MOPAR shaft rocker system? When in reality you can remove the pushrod and throw it 150 yards out into a field and the geometry hasn't changed one bit.

I too like the cup adjusters up into the rocker body that get rid of the excessive angle between the ball adjusters and the pushrods with the cup.

I'm doing my first set of EQ Magnum heads. With the valve lift, stem lengths and rocker arms chosen, I've had to do some moving of the rocker studs away from the valve tip towards the intake manifold. Thank God for the vertical mill.

This made me chuckle, even though it's not funny. Someone pays you to build the engine, because you have the tools and the knowledge and then they want to tell you how to build it. When **** goes sideways, the builder is always the asshole in the deal. So I stopped doing what the customer wanted and did what I wanted. I had a printed sheet with 5 other local builders with addresses and phone numbers I gave them as I showed them the door.


BTW, when you build an engine with the Hughes method of geometry and the problems start, does Hughes take the blame? Nope. They'll tell you you're a dumb *** and they never have issues.

FWIW, even though Dave and I don't agree on some stuff I get along with him. He even makes some stuff I use because it's easier than making it myself. But damn...he's been doing it long enough he should know better.

 

[dibbons]

Here's a video, I guess the experts here can tell us how accurate the presenter explains the issues.

 

[IQ52]

This made me chuckle, even though it's not funny. Someone pays you to build the engine, because you have the tools and the knowledge and then they want to tell you how to build it. When **** goes sideways, the builder is always the asshole in the deal. So I stopped doing what the customer wanted and did what I wanted. I had a printed sheet with 5 other local builders with addresses and phone numbers I gave them as I showed them the door.


BTW, when you build an engine with the Hughes method of geometry and the problems start, does Hughes take the blame? Nope. They'll tell you you're a dumb *** and they never have issues.

FWIW, even though Dave and I don't agree on some stuff I get along with him. He even makes some stuff I use because it's easier than making it myself. But damn...he's been doing it long enough he should know better.

I too buy things from Hughes. Even Indy, shudder!

 

[dibbons]

This tutorial states the rocker tip contact should be changing directions during valve opening/closing (my bold print).

From dvorakmachine.com :

OBSERVATION AND CORRECTION

NUMBER ONE PRIORITY is to ensure and correct as necessary, the relative valve tip heights (fig 1). The closer you can get them to each other, the better the effectiveness of your efforts.

This can be accomplished by doing the valve job, install the valves, locate the one that sticks out the farthest, and then go about the task of matching the "short" ones to the "long" one. This can be accomplished by regrinding the seats, grinding a wider 45 degree angle on the valve, effectively reducing the margin of those valves, and in some severe cases, adding a lash cap to the tip of the valves to make them think they are "longer". You can also dress the tips down of the longest valves if that helps equalize them. CAUTION, LIMIT WHAT YOU REMOVE OFF THE TIP OF ANY VALVE to about .020".

ONCE YOU HAVE EQUALIZED THE TIPS, you are now ready to deal with the geometry and scrub angle.

It is best to install the lightweight "checking" springs for this procedure. Actually, you need only start out with a pair of valves, one intake and one exhaust, a shaft, two shaft hold-downs and of course two rocker arms. For the purposes of this discussion, we will concern us with standard ADJUSTABLE IRON ROCKERS, such as Isky, Crane or other MAX-WEDGE type rockers. These are the most common street type rockers and offer tremendous gains over the OE stamped steel models.

It should be pointed out at this point that roller- tipped rockers have the same geometric requirements. The procedure to correct the scrub angle is similar, but small amounts of imperfect geometry can be tolerated much better than their cast iron counterparts. A roller tip does not actually "scrub" as we have been defining it, but rather the tip ROLLS across the tip of the valve instead of "pushing and/or pulling" as FIXED tip rocker arms do.

We do not like roller rocker arms for street use. Especially aluminum bodied ones or needle shaft mount rockers. If you feel strongly about using ROLER ROCKER ARMS ON THE STREET, I would recommend the Comp Cams Steel bodied roller tip. Use the same procedure to identify and correct geometry problems.

WHAT YOU ARE LOOKING FOR

For the purposes of identification we will break the tip of the valve into 3 parts. The center, the shaft side of center and the exhaust manifold side of center.

The old theory of having the center of the valve contacting the center of the rocker pad (roller) at one half of valve lift isn't close enough, at least with a stationary tip rocker arm. What you are looking for is the action of the rocker arm across the valve tip that changes direction as the valve opens. The action will appear as rocker tip moving across the valve tip and then back.

The center of the valve tip should start contact (at zero lash) slightly to the shaft side of center. As the valve opens, the center of the rocker arm should move toward the center of the valve (or just past it) and then at some point, reverse direction and come back to where it started when the valve is fully open. This action spreads the load against the guide and averages it out.

Improper geometry will look like the rocker tip is scrubbing toward the exhaust manifold side of the valve tip for the entire lift cycle OR PULLING back on the tip of the valve toward the shaft side during the entire cycle.

IT IS IMPERATIVE THAT THE TIP OF THE ROCKER CHANGES DIRECTIONS AS IT "SCRUBS" ACROSS THE VALVE TIP.

A roller tip rocker is okay if the roller center is on the center of the valve tip at half lift in most cases. Raise (with shims) or lower (by machining the pedestals or the shaft stands until you can accomplish that position. But if you observe the movement across the valve tip it should do the same as described for the stationary tip rocker. And that is start contact to the shaft side of the valve while the valve is closed, move across the tip just to center or slightly past, and then return to the original position during full lift. Then back to center at one half closed and back again to the original position when the valve is closed.

It sounds complicated but it is not. Put a checking spring on the valve, adjust the lash (or pre load) and rotate through a few cycles and you will be able to identify what is happening to the scrub angle. It will become clear to you and what to do about it will come easily.

Take care of this important part of the engine build. Your valve train will love you for it!

 

[AJ/FormS]

Well, I've seen more than a few Mopar running huge cams and laying down early because the geometry was off. The area under the curve of a smaller cam with good geometry is better than a bigger cam with poor geometry. Great power with good driveabilty. What's not to like?

I understand what you're saying and I like it. I certainly don't have enough experience to have proven it nor money to try to, and so I rely on guys who do. And you
should be on everybody's short list, cuz not only have you paved the way,and are generous enough to have shared your secret(s), but you also provide the parts and tutelage for us to build successful combos. And I for one give you a great big thank-you.

 

[IQ52]

Here's a video, I guess the experts here can tell us how accurate the presenter explains the issues.

"It's the same old story.........everywhere I go.......I get slandered, libeled.........I hear words I never heard in the Bible.........." I get it! Don't give a damn on the sweep width as long as it's in the center? Gag. Oh, And don't bother to tell us how we get a narrow sweep!

I didn't have to move the studs over on the EQ heads to get a centered, fat sweep. I could have just used a shorter pushrod.

But.......I sure had to move them............to get a narrow sweep that wasn't on the very edge of the valve.

I suggest, like Rosey did, y'all go to the B3 Racing Engines site. The most complete and accurate information is there.

 

[yellow rose]

Here's a video, I guess the experts here can tell us how accurate the presenter explains the issues.

That's not a bad video. Every Chrysler guy should watch the video and pay very close attention to the stud mounted rocker part of the video. Not so much because pushrod length changes geometry with a shaft, but to look at what happens when the rocker arm is too low.

When the rocker arm is too low, it will hit the retainer, just like it looks in the video. When you raise the rocker, it misses the retainer. On a shaft system you not only move the rocker up, you have to move it away from the valve. You must do both, move the shaft up and away from the valve.

 

[yellow rose]

"It's the same old story.........everywhere I go.......I get slandered, libeled.........I hear words I never heard in the Bible.........." I get it! Don't give a damn on the sweep width as long as it's in the center? Gag. Oh, And don't bother to tell us how we get a narrow sweep!

I didn't have to move the studs over on the EQ heads to get a centered, fat sweep. I could have just used a shorter pushrod.

But.......I sure had to move them............to get a narrow sweep that wasn't on the very edge of the valve.

I suggest, like Rosey did, y'all go to the B3 Racing Engines site. The most complete and accurate information is there.

Yeah, I didn't want to get into how to narrow the sweep with a stud mounted rocker. That may add confusion to the shaft guys.


The best info I've found for shaft rocker geometry is at b3racingengines.com and it's free. You can read it as many times as you want.

 

[IQ52]

And when you go to B3RE, pay attention to the fulcrum center and the roller center as it pertains to the valve stem tip at lift.

 

[rumblefish360]

 

[B3RE]

"
I didn't have to move the studs over on the EQ heads to get a centered, fat sweep. I could have just used a shorter pushrod.

But.......I sure had to move them............to get a narrow sweep that wasn't on the very edge of the valve.

Yeah, everyone seems to think stud mounts are easier to work with, but not when the studs have to be relocated. That's a major hassle.

The video is one more instance of someone who doesn't understand geometry,and the purpose of a fulcrum, trying to teach others what they don't have a thorough grasp of themselves.

 

[moper]

Dave Hughes can kiss my furry ***. I'll find other products. Haven't used anything from him, and the cam and lifters I bought in the early 90s is still in it's box.

 

[AJ/FormS]

Wasn't he the guy who brought the fast-rate,hi-lift, made-for-the-904-lifter, cams, to the forefront in the late 90s?

 

[yellow rose]

Wasn't he the guy who brought the fast-rate, made-for-the-904-lifter, cams, to the forefront in the late 90s?

Racer Brown was doing it long before Hughes.