Roller Rocker geometry questions

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Well I got some resolve today. I had few members PM me to discuss my rocker problem and I thank them. One in particular told me his story of rocker issues and was a great help. I will try to give the cliff notes version and try to get my point across. He explained at the time Edlebrock developed it's heads Crane Cams were the only ones making the roller rockers for early LA engines. So they cast the heads for the Cranes. Shortly later others started to develop rockers for the LA engines. This is the time frame when him and a friend both had a set of eddy heads. The difference, he choose to go with one of the new brand rockers. I don't remember if it was Harland or Hudges. His friend went with Crane rockers. The friends geometry lined up perfect and he had similar alignment to mine but on the other side of center, he was on the intake side. So he went into detail on how he fought to find a solution and the fix. It took him a long time, lots of phone calls and emails. To make it short he discovered that the Cranes compared to the other brands are a tad longer on the roller tip. That explained his inside geometry compared to his friend Crane rocker geometry. Digging further and deep into Edlebrock. As far up as finally getting to Vic Edlebrock. Apparently edlebrock was getting a lot of complaints that the other current rocker companies were having alignment issues. So they made the choice to change castings and move the mounting points for the rocker shaft to fix the geometry. This happen some time around the year 2000. So after getting Edlebrock to come forward with this information they offered to give him a set of the newer casting heads to fix geometry problem. This is why today a lot of people have the issue of running the Cranes on Eddy heads.

Any way I also talked it out with machinist today about it. He looked over the my alignment and told me even thow it is not ideal it's not bad and I would be fine with it. We discuss what it would take to fix the problem. Which included line honing the shaft seats to get them to sit lower. But he wasn't stressing over the alignment so I will go with it. Maybe later after I get the motor running and setup I can start to save for a new set of roller that fit right.

On another note I got a hold ARP about my short studs. It took several emails and pictures. They didn't offer any explanation for the wrong size. He even gave me the dimensions of what should have came in the kit. They are the right ones. He said I needed to use kit 144-4002 which is stated to be for the W2 heads. They are 1/2" longer on the top studs from what I have now. After all that they didn't make any effort to fix the problem. Ron F @ ARP basically told me I had to sort it out with Summit. Really? Whatever! I told him they need to change the requirements for their products so they don't confuse anymore future customers. I mean come on, my box says right on it they are for Edlebrock heads and apparently it contains the correct studs. All your going to tell me is I just need to get this other kit. Terrible service. Now I will have to fight over shipping cost with Summit over an exchange for a product that wasn't the correct one to begin with because they can't label their product right.

Rant over:finga:
 
It's all very well and good to cut the valve tips down [although I don't think you could cut them enough to fix this] but what happens when the OP puts a better quality set of rockers on this engine? They are not going to fit either because the valve tips are now too short. This is because IT'S THE ROCKERS that are the problem. Either live with it or get some better rockers.
 
raymond said:
It's all very well and good to cut the valve tips down [although I don't think you could cut them enough to fix this] but what happens when the OP puts a better quality set of rockers on this engine? They are not going to fit either because the valve tips are now too short. This is because IT'S THE ROCKERS that are the problem. Either live with it or get some better rockers.
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Nope, its the stem height.

Did this so called machinist even tell you the current installed stem height???
That is the biggest crock I have ever heard, and the detail of the machinist talking about honing the rocker saddles without doing a sweep test by simply dropping the valve down the measly .020 or so thousanths and open closing the valve with the rocker dye tells me someone needs a new machinist.

Oh well, enjoy your mopar.
 
Skrews - I did review that diagram and there are two things I don;t like about it... It doesnt show a rocker shaft centerline, which for the purposes of my opinion is crutial; and it doesn't make note of the relationship between the two different angles of the valve centerline and the centerline of the rocker shaft stand. Because those two angles are tipped towards each other, simply shimming the rocker shaft up will not solve this issue. I'll simply say we disagree as there are many instances of builders disagreeing on setting geometry - even on relatively simple setups like Mopar where there is only two variables that contribute: stem height and rocker shaft centerline.
Stumper - This is a problem created by poor machining and it can be simply and permanently fixed at this point. It's not exotic. It's simple quality control as the engine builder.
Raymond - Ii is part of any valve job to cut the stems down. It's also very common for shops that do more GM-type stud rockers to screw things up. The shims available are made from .010-.050 thick IIRC. Trimming what is needed off those would be nothing crazy and take a shop a couple hours at most.
71Swing - I would question validity of your story. not the intention of any party - but the details and reasons. Time tends to cloud the mind and you're referring to second or third person memories of years ago. The RPMs were designed dimensionally for factory rocker hardware. All aftermarket rockers have minute differences that will affect the swipe pattern, but all are basically the same at mid lift in terms of where the contact is when the rocker and valve should be at 90° to each other. I've been an RPM user since they became available in the late 90s. No set was ever installed out of the box because the first set's valve job was so bad that when the shop showed me I refused to run them that way. Rockers used included Isky iron, Crane iron and roller, stock stamped, Comp steel roller, and some Chinese set. The only issues found have been spring clearance on occasion and that Chinese crap was horrid all around. Attached is the last set that uses Isky's iron. A roller tip will have a narrower pattern and it's less important to have the pattern centered. But - any deviation from center is three things: lost lift, more sideloading of the valve on the guide (frictional power loss and wear), and a lower rpm threshhold for loss of valve control (harmonics and "float". It will certainly work as you have it. But as you are still in the assembly phase, the fix can be done reasonably easilly.
 

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1wild&crazyguy said:
Nope, its the stem height.

Did this so called machinist even tell you the current installed stem height???
That is the biggest crock I have ever heard, and the detail of the machinist talking about honing the rocker saddles without doing a sweep test by simply dropping the valve down the measly .020 or so thousanths and open closing the valve with the rocker dye tells me someone needs a new machinist.

Oh well, enjoy your mopar.
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I agree...ran into this problem with a set of dart heads with harland sharpe rollers. Machinist corrected the stem height and the geometry was correct through the entire valve cycle. (this was on a sb chevy)
 
In the OP's pics we can clearly see from the ink mark(representing the scrub pattern) that the scrub pattern is out toward the exh side of the valve tip.

f6751311-8d0a-4cd6-b4d4-cf5be2d56310_zps60bfed3c.jpg



In The next pic is another head with a similar problem. Note the position of the rocker tip on the valve tip at the closed position.


scrubclosed_zps61e5ddd2.jpg



The next pic shows the same head with the valve open. Note the rocker tip is now even further toward the exh side of the valve tip. As can be seen the rocker tip will not travel back toward the rocker shaft side of the valve tip until it reaches about the 3:00 o'clock position. This would require the valve tips to be lowered about .500" in order to move the scrub pattern in toward the rocker shaft. Looking at the above pic one can see that moving the valve tips up will push the rocker tip back toward the rocker shaft, thus moving the scrub pattern toward the center of the valve.


ScrubFullyOpen2_zps46a5790a.jpg


pic of scrub pattern from above 2 pics


RockerScrub_zps5abfb5b7.jpg
 
I had the same problem with my 273 heads. Between a valve grind and new valves and not grinding the stems, things didn't look good. I shimmed the shafts and had to get longer pushrods to fix the problem. I could have (should have) ground the stems to fix the problem. tmm
 

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The Crane Gold rocker arms I bought have the roller tips positioned like the original poster's rocker arms.

When I put the Mopar Performance stamped rocker arms (they came on my engine to begin with) on my Edelbrock heads they line up pretty darn good.

Is there a brand (or brands) or rocker arms that provide the best (better than the Cranes) geometry?

Harland Sharp?
Hughes?
Comp Cams?
PRW?

Or is all a crap shoot?

Paul
 
Skrews - Look at the two pink lines in picture one. There is no way to raise the shaft and get the result needed. The only way is to either run the valve shorter (and the change is not "1/2 inch") or mill off the rocker shaft stands and run support blocks that can properly locate the rocker centerline. The problem with that head is the valve is either the wrong part (.100" longer?) or someone sunk the valve. If the placement of the rocker tip is checked at mid lift it's almost off the valve. There's some basic wrong stuff there.
 
1972DusterPaul said:
The Crane Gold rocker arms I bought have the roller tips positioned like the original poster's rocker arms.

When I put the Mopar Performance stamped rocker arms (they came on my engine to begin with) on my Edelbrock heads they line up pretty darn good.

Is there a brand (or brands) or rocker arms that provide the best (better than the Cranes) geometry?

Harland Sharp?
Hughes?
Comp Cams?
PRW?

Or is all a crap shoot?



Paul
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You might try some Hughes rockers, when they first brought them onto the market they said that they had actually made changes so that the geometry was correct, but nothing is perfect. I think you have a better chance of getting it right with the Hughes ones than the Cranes. The Cranes ones have a design problem, that's what this whole post has been about not sunk valves, or valve stems too long or anything else.

HULLO IT'S THE ROCKERS!!!!
 
moper said:
Skrews - Look at the two pink lines in picture one. There is no way to raise the shaft and get the result needed. The only way is to either run the valve shorter (and the change is not "1/2 inch") or mill off the rocker shaft stands and run support blocks that can properly locate the rocker centerline. The problem with that head is the valve is either the wrong part (.100" longer?) or someone sunk the valve. If the placement of the rocker tip is checked at mid lift it's almost off the valve. There's some basic wrong stuff there.
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I never said anything about raising the shafts. I've been saying the opposite, that the valve tips need to be raised via longer valves or lash caps which in effect does the same thing. Look at the picture. You can see that as the rocker tip follows the trajectory of the arc, it moves toward the rocker shaft, thus moving the scrub pattern more on to the center of the valve tip.

scrubclosed_zps61e5ddd2.jpg


These pics were grabbed from this thread http://www.forabodiesonly.com/mopar/showthread.php?t=41037 the heads are new OOTB. The real problem in both scenarios is that the rockers are to long for the shaft saddle to rocker tip distance. In both cases the best cheap fix is lash caps, which may not even be enough. Usually the ductile iron rockers don't have this issue. Score one for the old school.
 
If you have access to a bunch of different brand roller rockers, grab one shaft and slide one of each, side by side and notice the variation in roller pin location, pin to shaft centerline. It's a big variance for something that's designed to fit the same head. Some will be close others not so much! BB mopars have the same variation from manufacturer to manufacturer.

Cranes look like that on just about every SB mopar I've ever seen and good luck fixing it without significant machine work. Harlands were even worse towards the exh side. Moving the shaft is essentially the only way to fix it to get a proper in-out-in sweep.

Hughes rockers are actually pretty good from a geometry/sweep standpoint.
 
Crackedback is right. The Hughes on my engine are right on the money and the Cranes were right where yours are. You'd think that they would be closer than they are from one supplier to the next but apparently not.
 
crackedback said:
If you have access to a bunch of different brand roller rockers, grab one shaft and slide one of each, side by side and notice the variation in roller pin location, pin to shaft centerline. It's a big variance for something that's designed to fit the same head. Some will be close others not so much! BB mopars have the same variation from manufacturer to manufacturer.

Cranes look like that on just about every SB mopar I've ever seen and good luck fixing it without significant machine work. Harlands were even worse towards the exh side. Moving the shaft is essentially the only way to fix it to get a proper in-out-in sweep.

Hughes rockers are actually pretty good from a geometry/sweep standpoint.
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Agreed!
 
crackedback said:
If you have access to a bunch of different brand roller rockers, grab one shaft and slide one of each, side by side and notice the variation in roller pin location, pin to shaft centerline. It's a big variance for something that's designed to fit the same head. Some will be close others not so much! BB mopars have the same variation from manufacturer to manufacturer.

Cranes look like that on just about every SB mopar I've ever seen and good luck fixing it without significant machine work. Harlands were even worse towards the exh side. Moving the shaft is essentially the only way to fix it to get a proper in-out-in sweep.

Hughes rockers are actually pretty good from a geometry/sweep standpoint.
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Agreed ! X2
 
Great ...lol...yeah relocate the shafts...It's way easier than centering the sweep by just grinding the stem heights.

Ive setup aluminum rockers and had this problem before, I ground the stems, fixed.

Good luck with the re engineering..lol!!
 
71 - You said they "cut the seats". I assumed these were the valve spring seats. Was it spring seats or valve seats?
As far as rockers go:
Harland Sharps as I understand it were designed for longer valves. I have not run them myself, but others have commented to that on other sites.
The Iskys tend to have machining chips in them but otherwise a very good product - may need minor clearancing for the springs.
Crane - the only issues I've found with iron and rollers over the years are the bad adjusters some years ago, and they can sometimes cause some harmonics because of the location of the pushrod cup. That was done to get a faster motion in the beginning of the lift cycle, but it also means the closing ramp can be fast and cause bounce. That was a conscious design choice they made and why I'd call them more of a street rocker rather than race rocker. High rpms can be a problem with them. I have 4 sets currently in service - 3 are 1.5, one is a combination of 1.5 and 1.6. All are on RPMs, and all had competition 5 angle Serdi valve jobs done prior to use. None showed any swipe pattern issues, and all are centered on the stem at mid lift.
Indy 1.5s were fine.
Chinese were total crap.
Comp steels were good, agins on RPMs, and same prep as above. No issues.
Stock stamped - used on factory iron - same prep, no problems.

It comes down to one of those "to each their own" deals. Personally - I don't subscribe to "its the rockers" and I don't subscribe to needing lash caps. I get the valve job right - historically it's worked for me and my engines.
 
Just because the pattern looks correct, does not mean the sweep is correct.
 
The spring seats required machining because the springs my cam called for are taller than the stock eddy springs. Got my one lash cap today I ordered. Slapped it back together. Like mentioned earlier in the threads I don’t think it helps tip placement, but I would think it would help distribute the load to the valve tip more. I defiantly give more surface are for the roller.

roller on the right with lash cap roller on the left without.
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Zero lift
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half lift
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full lift
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roller patterns
dsc06109jz.jpg
 
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