roller rockers

[SIXPAK]

Jesels' part number for the 4.0 is KPS-03422 and price is..ready...$1173 buckaroos. Can be ordered anywhere between a 1.55 to 1.85 in .5 increments for that price.

[gradon]

. . .and I was griping about paying $400 for Yella Terras. . .

[Gearhead88]

Any opinions on Mopar roller rockers ?

I've broken a few of them.

I went and typed a long , detailed post with pictures , then lost it

Rather than re-type the whole thing , how's about a link to a performace discussion Istarted elswhere.

http://forum.calgaryjeep.com/index.php?topic=10789.0

Lots of pics , please read before responding .

[SilverXJ]

Yes, they required the valve cover and t-stat housing spacer.

[dwg86]

They both broke in the same place. I wonder if it has something to do with the valve adjusters in the end. I am going to try the Harland Sharp S4096 Rocker Arms. With using the stud nuts to adjust the rocker arms, I am hoping that a valve cover spacer is not needed. Also there is more material left in the rocker where the pushrod goes(compared to the mopar).

[Gearhead88]

They both broke in the same place. I wonder if it has something to do with the valve adjusters in the end. I am going to try the Harland Sharp S4096 Rocker Arms. With using the stud nuts to adjust the rocker arms, I am hoping that a valve cover spacer is not needed. Also there is more material left in the rocker where the pushrod goes(compared to the mopar).

I know a couple of guys that use Harland sharp roller rockers , so far , so good but they are both trailer queens and do not see the milage mine does.

Here's what has happened , my 4.7 went together well with no surprises , the roller rockers were added later. Initially I had used a set of new , stamped steel rocker arms , the engine performed well , awesome throttle response , VERY torquey , the valve train was a little noisy , I had attributed the noise to the fast acting ramps on the Comp cam I had used . Like I said the roller rockers came later , I was concerned about where the adjusters were , as in the thread had to be backed right off ,to the end of the available thread , so the lifters were not being preloaded when the rocker arm hold down fasteners were torqued. There was adequete adjustment available , I was able the achieve the 1/2 to 3/4's of a turn necessary to preload the lifters.It all looked good but they were a little noisier than I had expected , about the same as the steel rockers , so I ran with it. All was good , till about 5000 km , then without warning the # 5 intake rocker broke. I removed all of them and ordered another pair from my Chrysler dealer and went back to the steel rockers . A short time later , once I had recieved replacements , the roller rockers went back in . All was well again , a bit noisy , as before , another 5000 or so km later , the #3 intake broke. The steel rocker arms are back in it now and it's running great.I should mention , I'm using a set of Comp cams Magnum pushrods with this set up , #7657-16 , the length is 9.600" , a nice stiff , well made pushrod and no guide plates , the Mopar rockers do not call for the use of guide plates.

Here's some pics..................





The wierd thing that should be pointed out is , the strange side loading that is taking place on the roller tip , not visible on the first failure but quite obvious on the second failure event , on several rockers , 4 of em , two of those that did not break.






The engine , like mentioned , runs well , there was no additional damage , no bent pushrods , mashed valve seals , broken valve springs. . I'd like to find the reason for the failures , is there some kind of instability with the lack of guide plates ? , some kind of flexing ? , harmonics ? , beats me , the pushrods in these engines are quite long , is there some flexing / deflection deal going on ?


In the mean time , I have other on going projects happening , a performance 2.5 build , a second 4.6 stroker build w/ ported head and + .060" valves.

some pics...........................








This one is getting beehive springs , necessitating the machning of the valve spring seats.






The fun continues

[6TIME]

Nice looking port work! Just curious, what springs were you running when your rockers failed?

[Gearhead88]

Nice looking port work! Just curious, what springs were you running when your rockers failed?

Comp cams # 926 , they come in the "K" kit , which come with cam , lifters , springs , retainers & valve locks , timing set & lube . Strangely , Comp Cams is not up to speed with things , the retainers and locks in the "K" kit are for 4.2 w/ 3/8" valve stems so retainers and locks must be substituted to make the springs work , in this case , I measured a bunch of retainers I already had and based on the spring I.D. / O.D. and what Comp has in thier catolog , viewing the charts there , I used some steel retainers from a Harley Davidson Evolution , I had lots of those available. The next head I'm doing will get Comp beehive springs , for a number of reasons , lighter , high grade ovate wire , the ability to run a less aggressive spring with a given camshaft , less mass , smaller / lighter retainer , more clearance where the springs are in close proximity to the valve cover and more . Not new technology , just more advanced than traditional multiple springs , that often place un neccessary stress on valvetrain components if the springs are not carefully chosen

[Alex22]

The rocker arm circled in red looks like it was rubbing on the bolt causing the entire rocker arm to be forced away from that side and that put a side load on the arm causing the roller tip to dig into the lifter body. It also looks like the arm became bound up on the bolt and that put a lot of extra force on the pushrod side of the lifter and caused a failure. The reason that no pushrods were bent could be because they are stock style non hardened ones that would spring back after being jammed into the body. It would also explain why the valve train made more noise than it should have.
The rocker arm that was circled in yellow looks like it was binding up on the side the same way the other one was but it did not bind when it was opening the valve.
Does the MP rocker arm set come with shims to center the lifter over the bolt, if not some HP valve spring shims will usually work to correct misaligned rocker arms.
Are there any wear marks on the third lifter in that picture that would suggest it was not centered over the bolt?

~Alex

[Gearhead88]

The rocker arm circled in red looks like it was rubbing on the bolt causing the entire rocker arm to be forced away from that side and that put a side load on the arm causing the roller tip to dig into the lifter body. It also looks like the arm became bound up on the bolt and that put a lot of extra force on the pushrod side of the lifter and caused a failure. The reason that no pushrods were bent could be because they are stock style non hardened ones that would spring back after being jammed into the body. It would also explain why the valve train made more noise than it should have.
The rocker arm that was circled in yellow looks like it was binding up on the side the same way the other one was but it did not bind when it was opening the valve.
Does the MP rocker arm set come with shims to center the lifter over the bolt, if not some HP valve spring shims will usually work to correct misaligned rocker arms.
Are there any wear marks on the third lifter in that picture that would suggest it was not centered over the bolt?

~Alex

You've brought forward a few comments that prompted a second look at the rocker arms , I have had little time to look closely at them till now.

The rocker than you have circled in red ? , the marks are merely a reflection of light off of the needle bearings , no evidence of rubbing on that one.
The rocker circled in yellow , does indeed have a rub mark , only deep enough to have created a shiny spot through the anodizing , I can't feel a groove or any removal of material.

Each rocker , when assembled on it's shaft , is positioned between thrust washers and retained with snap rings , The rocker arm lateral / axial play is .020" , which seems a little excessive , and would allow a rocker arm to make occasional light contact with the pedistal / spacer that positions the assembly , no evidence of binding , .020" of side play would not allow any binding to take place . Shims are not provided with these rockers or any literature either.
A few of the other sets show the same shiny spots described above , no grooves or damage . The rockers were well aligned with the tips of the valves , however the axial movement and wear on the roller tips confuse me . When the valve job was done , each valve had its tip cleaned up on the valve grinder as needed , a minimal amout of material was removed to clean them up. Another item I should mention is , some of the rollers are wearing , you can catch a finger nail on the edges , this tells me that the rollers are very soft and not up to the job , not very impressive. I checked the axial play on the roller tips and found .018" on the rockers that have no wear in this area.

It would be possible , to botch the installation of these rockers , I don't feel that this is the case here , until otherwise proven , I believe it's a quality issue. The failures happened after several thousand kilometers , both times , separate events a year apart , in total two of the twelve rockers failed , others are showing strange wear patterns that could potentially lead to failure in the future.

Adjustable rocker arms should not require shimming below the hold down fasteners , If I'm wrong , an explanation would help to clear that up.

Also , the pushrods , as mentioned , are Comp cams Magnum , .080" wall / 5/16" , chrome moly & heat treated.

Whatever the cause of the noise or failure , I'm not comfortable with the quality of these parts or the sounds that they make and will not be using them until I understand what has happened and can correct it. The stock rocker arms that are in it now run with less noise , not silent , just better than with the roller rockers. I'm not at all impressed with these rockers and feel I have wasted a lot of money on them.


It would be helpfull to know if others have experienced any failures on Mopar rocker arms , or any other rocker arms for that matter. If I ever buy roller rockers for one of these engines , I'd like to spend money on something that is known to last.
I've used cams that are a whole lot more aggressive than what I'm using now , on a variety of engines , some with roller rockers , some without. There is a wide variety of rocker arms available to suit a vast number of applications of which , there are differing levels of quality on these parts.

A call to the 1 800 FU2 # at Mopar peformance turned into a conversation that went no where , the Bozo on the other end pretty much blew me off .

[Alex22]

At the bottom of this page there is a picture that explains shimming under an adjustable rocker arm
http://www.eatonbalancing.com/blog/2007 ... -geometry/
I didn't read the entire page, just looked quick and found the picture to explain what I was talking about.

Was there any wear on the bar or were the rocker arms twisting on the bar?

I'm going for steel roller rocker arms whenever I get a chance to work on my stroker again.

[Gearhead88]

At the bottom of this page there is a picture that explains shimming under an adjustable rocker arm
http://www.eatonbalancing.com/blog/2007 ... -geometry/
I didn't read the entire page, just looked quick and found the picture to explain what I was talking about.

Was there any wear on the bar or were the rocker arms twisting on the bar?

I'm going for steel roller rocker arms whenever I get a chance to work on my stroker again.

No visible wear , I've not measured them yet . I've stripped the damaged sets as salvage , for parts. There's enough good rocker arms left to outfit a 2.5 which I just happen to be rebuilding / hotrodding , not that I'm gonna use them after losing confidence in the quality and strength of these parts . The rocker arm needle bearing to shaft fit seems to be within spec , whatever that may be ?

That link leads to a good description of rocker arm action , even better than what is shown in the Comp catalog , thank's

[novacayne75]

last week while i was assembling a 4.5 for another member here i had some down time and decided to see what i had that may fit. a 1.7 bbc rocker looked like it should work,7/16 screw in studs,sbc adjustable guid plates. the stud bosses will need to be milled down but i dont see any other reason for it not to work . im gonna find an old head to play with this combo and if i can get a proven setup i will make some kits . i think i can do it for less than $200 with off the shelf parts.

[dwg86]

Cool, keep us informed. Do bbc roller rockers come in 1.6 ratio?

[yuppiexj]

last week while i was assembling a 4.5 for another member here i had some down time and decided to see what i had that may fit. a 1.7 bbc rocker looked like it should work,7/16 screw in studs,sbc adjustable guid plates. the stud bosses will need to be milled down but i dont see any other reason for it not to work . im gonna find an old head to play with this combo and if i can get a proven setup i will make some kits . i think i can do it for less than $200 with off the shelf parts.

Here's a page where it's been done and he was nice enough to put the machinist drawings out for all to see.

Page 1
http://members.tripod.com/~Mojo_Page/Rokr1.htm

PAge 2 with drawings
http://members.tripod.com/~Mojo_Page/Rokr2.htm