FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: Monzy on August 02, 2013, 08:37:59 PM
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So I've got about 1000 Miles on this build and have broke 2 rocker arms within those miles, 1 being just last week and can only lead back to spring pressure. These are standard 1" wide Dove rollers on 496lbs open springs. Too much pressure for these I take it? They seemed great for 1/4 mile runs at 6300rpm but broke while driving in town normal. The last one was on the exhaust side causing the intake pushrod to bend also. I've yet to get a new rocker or pushrod because I'm afraid another is going to break and give me more pain then a $30 rocker or pushrod. Has anyone experienced extensive damage due to a rocker arm breaking? I'd upgrade to the T&D or something better but those are big dollars! Do the T&D even bolt onto an edelbrock head without changes?
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Yep, too much pressure for those rockers. The aluminum fatigues after a while and will break. I think T&D makes a less expensive set now that would hold up in your application, and is a bolt-on deal.
I assume with that spring pressure you have roller lifters? You can definitely damage those by running them after the rocker breaks. If the roller isn't in contact with the lobe the lobe is smashing up against it at some point, which can damage the roller wheel and needle bearings. Hate to say it, but I would really recommend replacing the two lifters where you had the failed rockers, to be safe.
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Seems to be a "luck of the draw" deal on Dove rocker breakage. I've had some last forever with higher pressures than yours - and have had some break for no apparent reason with flat tappet pressures. I have a mix/match collection of rockers here if you need one or two...
And T&D does sell a bolt on set that works well in applications like your's or milder and requires no head machining. Harland Sharp also sells a very decent bolt on kit.
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You are about a 100lbs over the recommened pressure for those rockers.
no wonder they gave up.
Not Dove's fault this time.
I believe they list the standards for up to 400lbs open.
anything more than that and you need the wide ones.
garyv
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I fished the comp roller lifter out from under the intake to check them out and don't see any obvious signs of damage but cant get over the fact I can feel a little something on the one roller but also noticed those needle bearings are not caged and free to roll up on each other and maybe thats all i'm feeling. Either way i'm on the paranoid side and will replace the damn thing. Putting it back in with the intake off will be more fun i'm sure! I almost feel like pulling the intake to check them all but want to replace the PI intake for an RPM at a later date so not ready to take a perfectly sealed intake off unless someone wants to trade! ;D
I actually didn't know the standard Dove rockers were only rated for 350+lbs untill recently. Time to bite the bullet and get those T&D's like I was going to originally when the first one broke. Hopefully I can get a few dollars for the set of Doves to offset the damage to my pocket.
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Here is an idea that will work just fine.
Keep the Dove setup and just replace the rockers with some Harland Sharps or some Pumpbuilders.
they are around $400.
This will save you a bunch of money instead of replacing everything.
Good Luck no matter what you decide to do.
garyv
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Would the pushrods be different lengths or cups with T&D or Harland Sharps from what I already have?
I have to replace one of the smith bros pushrods and looking at their chart for tube ends seems a little hard to determine what I actually have. What cup and ball do you guys use for Comp solid rollers and Dove rockers? Might be irrelevant if I have to replace all 16 pushrods when I switch rockers or setups but as far as I know they're all 1.76 ratios so wouldn't that mean they're the same length pushrods unless the mounting is changed.
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I haven't tried the Harlan Sharps or the bolt-on T&Ds, but they should use the same length pushrods as the Dove rockers if the adjusters are the same.
Without checking I'm pretty sure that the balls on the adjusters are 3/8" diameter, so you should buy pushrods with that cup size. On roller lifters, the ball end on the pushrod is usually 5/16", which tends to confuse things...
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T&D bolt on rocker gear is 5/16 cups on rockers. I am pretty sure..
or i have the wrong pushrods in my engine :o
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Ok so it looks like if I get the T&D setup I'll have to get all new pushrods because they use the 5/16th cup style instead of the 3/8 ball style adjusters. That's a $200+ dollar expense.
The Harland sharp does use the 3/8 ball style adjuster so I could use my current pushrods but just like dove they're not a true roller rocker unless you upgrade to the 7/8" shaft. If I kept the stock size shafts I would end up with bronze bushing rockers, not rollers like the 7/8" shaft size offer or T&D have.
I still haven't found out what the Harland Sharps (with bronze bushing) are rated for when it comes to spring pressure.
What bullet do I decide to bite? T&D and get new pushrods or bronze bushing Harland Sharps with my current end stand/spacers and shafts. The Harland sharps are a 1" wide body like the Doves, correct? If not then even my spacers are no good.
Either way I'll be eating Kraft Dinner but for how long all depends on what I get. :-\ I want to know I can start the Mach up and go for a drive without wondering if a rocker is going to break. Poor thing just sits there broken most of the time.
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I have Harland Sharps myself, and now that they are mentioned at what point are they good for?
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Checking out to see whats new on the FordFE forum I see more rocker arm failures and some very valid points about why we're even using these aluminum rockers? Can I just use a set of adjustable stocks with my 496lb springs? I don't think I've ever read someone breaking a stock rocker. Look at all the neat things I get to replace by going roller.
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I'll cross post what I wrote in the other forum regarding rockers. At least some of it applies to this discussion:
First is that the rocker broke exactly where they do - at the intersection of highest load and thinnest cross section. Whether the failure was from an assembly, machining or a material defect I cannot say.
That is the weakest area on a rocker and you cannot add much more material there with factory shaft diameters - one of the reasons that a T&D or Erson runs a high quality, but smaller diameter shaft. It is also the reason that I do not particularly care for thick walled bushings in most rebuilt stock or aftermarket rocker arms. The only broken stock arms I ever saw had bushings in them and the failure looked exactly like this one.
The roller tip does bring a benefit over the rounded to stock rocker. It uncouples the rotating rocker from the vertical motion of the valve - improving guide life and reducing drag & heat at that interface. One need only watch Bill Conley's SOHC high speed valve action videos to see the amount of heat generated by a sliding contact - he literally had smoke coming off the tip of the valve. The benefits here are likely to be pretty small though in the context of a mild street build.
A bearing at the fulcrum seems to be a good idea. At least it seems that the evil GM LS stuff has been running bearing fulcrum rockers in OE performance applications for several years now. I kind of like the honed ID/bushing at the fulcrum myself - seems to have fewer parts and works OK on wrist pins with few failures. Could be a toss up. Likely a great place for a thinwall bushing on a slightly reduced shaft diameter - or some sort of DLC coating on the rocker's parent material.
Steel is a better material for rocker arms - no question about that. Its a matter of mass versus physical size versus load capacity versus fatigue strength. But given good design, and good quality readily available aluminum alloys, fatigue failure is something to be concerned with in a .800 lift solid roller application running 8000+ RPM in a 500 mile race and never should be a concern in any normal street application. There are eighty gazillion street cars running down the road on aluminum rockers virtually forever, and at least a few OEM aluminum performance rocker applications that doubtless passed durability testing - so aluminum as a material is certainly good enough for this application.
The pushed out adjuster might provide the best clue here. As once explained to me by a Federal-Mogul piston engineer, aluminum alloy heat treating is more complex than initially meets the eye. Some processes will deliver a part that is initially "better", but which will degrade over time with heat. Alternate processes will not look as good initially, but will be more stable over time and can actually be a better choice for a given purpose. This is a long way of saying that the material may have looked and tested perfectly good at the point and time of rocker manufacture, but have not really been correctly treated at the extrusion supplier end. If it were possible to check it to the root cause might have been something as simple as a clogged gas jet in an oven somewhere that hurt a single stick of material...
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Thanks Barry, I learn new things here all the time.
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It's too bad that Comp (or another beyond Shelby or PRW) doesn't make a modern SS rocker for the FE as they do with stud mounted engines. One of the selling points, aside from sheer strength, is the relative lightness of the compact design, something one can't do with aluminum that requires some pretty bulky rockers to withstand high spring pressures.
http://www.compcams.com/information/Products/RockerArms/HiTechStainless.asp
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Several thoughts come to mind.
First, the NASCAR engines that come out of Roush's shop use rockers made of aluminum. They are made 'in-house'.
Second, as Barry mentions, you have, in an FE rocker arm made of aluminum, the same sort of assembly as you have with a wrist-pin in a piston. I can't remember ever seeing a piston with bushed wrist-pin holes, to say nothing of having to go to needle bearings there.
Third, you might call Dove regarding upgrading to the wider rockers. You DO seem to be running enough spring pressure that it might be worthwhile. I'd try pointing out to the Dove folks that you have had two failures in a thousand miles.
Fourth, again as Barry points out, there are simply design parameters inherent in aluminum rockers that are completely divorced from the manufacturing source. There's simply just so much room available between the shaft and the adjuster and there must be clearance for the cup on the push-rod, etc.
KS
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It's too bad that Comp (or another) doesn't make a modern SS rocker for the FE as they do with stud mounted engines. One of the selling points, aside from sheer strength, is the relative lightness of the compact design, something one can't do with aluminum that requires some pretty bulky rockers to withstand high spring pressures.
http://www.compcams.com/information/Products/RockerArms/HiTechStainless.asp
But they do.
I have a set of those PRW. I've never used them. I just don't have enough cars for all my FE junk I collect. ::)
I've checked them out pretty good and they seem good. With micrometers and fitment.
I've not had a set of the Shelby's in the paws.
I've noticed the price of them PRW's has gone up a lot. :o
http://www.prwonlinestore.com/fordfestainlesssteelshaftrockerarms352-428175r-3239022.aspx
http://www.shelbyengines.com/collections/misc-parts/products/shelby-fe-rocker-arms
(http://i135.photobucket.com/albums/q128/ScotiaFE/PICT0055-1.jpg) (http://s135.photobucket.com/user/ScotiaFE/media/PICT0055-1.jpg.html)
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I actually didn't know the standard Dove rockers were only rated for 350+lbs untill recently.
Can someone post a link showing where Dove states the rates for both the narrow and wide version of this rocker? I'm spooked seeing this since I have the narrow version of these rockers and run a hyd roller cam with 385lb open pressure. I'm also getting my car prepped to go race at Bonneville next month and sure as hell don't want this happening in BFE Nowhere between here and there. :o
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Anyone with real time experience using the PRW stainless steel rockers? The Shebly rockers being stainless steel are also on my list but above what I'd like to pay. At the same time I don't want to put a price on reliability and safety though.
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Anyone with real time experience using the PRW stainless steel rockers?
I have a set of the PRW stainless steel rockers in the 390 in my Galaxie. I'm using the Comp 270S cam and only 350lbs open spring pressure. Have done about 1000 miles on them, no problems so far. Although, when installing them, I couldn't get the ends stands the kit came with to fit, so I swapped a set of POP end stands I had. They then went together fine.
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Thanks ToddK for the update. That doesn't really say much for a rocker set built specifically for our engine to have a part of it not fit. I've looked everywhere and can't find much feedback on the PRW stainless steel rockers. I think its where they're made for the most part. They certainly look like a good strong setup.
I'm starting to feel a little stress on this rocker issue. To many people with a rocker arm/shaft/adjuster issues that I don't know which way to go!
I've got a little .581 lift solid cam with 496lb springs spinning to 6500rpm at times. Do I just get the T&D streets with new pushrods and pay the price to play or what? I've come so close to just getting some Harland Sharps as not many have a problem with them but again they're aluminum with the same size rocker shaft just like the Doves so why wouldn't they break eventually...
I Should probably note that these springs have a rating of 496lbs at 1.250" They have an installed height of 1.900" and with my cam they only compress to 1.317" Not exactly sure what the rocker is seeing for spring weight but its less then the 496lbs they're rated at.
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Can someone post a link showing where Dove states the rates for both the narrow and wide version of this rocker?
Sorry all, not to hijack this too far...
I have the Comp Cams 1046 units, non-HD wide version, which I understand are made by Dove for Comp (or perhaps it's the other way around?). On Comp's catalog here on pg 318 it states they are only rated for 350lbs open pressure.
http://www.compcams.com/catalog/COMP2012/pdf/COMP_Catalog_2012_312-327.pdf
The hydraulic roller cam I'm running is .633 lift 242/242@.050 with 385lbs open spring pressure in my 428. I've already replaced the adjusters with Smith Bros units as the oem adjusters are absolute crap. Never had a problem yet, but I doubt I've got 1000 miles on this new motor. Given it is a hyd cam, should I be concerned?
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Yes, Dove manufactures those rockers for Comp Cams. Including the adjusters that you had problems with. As Barry said they are hit and miss in terms of whether they will survive high spring loads, but 385 pounds isn't that bad. I'd continue to run them but be aware that they could break. If you start hearing valvetrain noise shut 'er down right away...
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I once asked the tech at HS about how well they would hold up to 600 lbs open pressure. He said no problem at that pressure. They are beefy rockers and they did hold up just fine with those springs.
If I recall correctly, the Comp/Dove rockers used shorter pushrods than the HS rockers so you would need new pushrods if you switch to HS.
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I once had an extended discussion with Ray Paquet regarding Dove wide rockers. As you can well imagine, he has a pretty aggressive cam and concomitant components in his FE race motors. All boiled down, his position about the Dove items is, "Put 'em in and forget 'em!" Good enough for me!
KS
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I see so many posts on both forums about fe rockers .Very seldom does anyone mention cranes rocker setup #34790-16 I believe is the number .Around 2005 I purchased this setup from crane (actually barnett performance in Atl.)The only thing was I had to have the rocker shaft stands milled down to get my valve train geometry correct .Mine set was one of the first and from my understanding this has been corrected by crane .These rockers dont have bushings like the above mentioned doves Mine have withstood 145 closed and 385 open spring pressure on the sollid flat tappet cam in my 452 and several 6000-6200 rpms .A roller cams spring pressure might show some strain but I dont think so.I just wonder why it seems I am the only person with the crane roller rocker assemblys .Whenever I bought them they were about $500 .At the time that was inexpensive and they come with arp studs for the shafts .The rockers are alum.with a std. size shaft and iron stands .The end stands are similar to what everyone else does .When I checked my rocker to valve tip it was really on the outer edge of the valve tip .I had my stands milled by my machinist at my job until it was more centered.Crane supposedly milled the rest of the ones they sold .But again I am just curious why there isnt much mention of this rocker setup it is another option fe guys should be aware of .Doug 8)
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I think one reason you don't hear a lot about the Crane setup is that Crane went bankrupt and quit selling parts for a while a few years ago. So they probably never sold a lot of these sets, and in fact I don't know if they are back selling them now. Other than that, I don't know why you wouldn't hear more about them.
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Crane does list them in their catalog http://www.cranecams.com/320-322.pdf (http://www.cranecams.com/320-322.pdf) and you can find them online. The rockers themselves look very beefy for aluminum units, looks from the photo like they don't use a bushing on the main shaft.
http://www.cranecams.com/product/secure/images/products/8690.jpg (http://www.cranecams.com/product/secure/images/products/8690.jpg)
Spendy kit at $900 though. However, if they are rated for big spring pressures, this could be a good value. I'd be interested to know what spring pressures they rate these to and what the physical dimensions of the rockers themselves are width wise.
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FWIW, I've been running HS rockers for three full seasons of bracket racing w/ a solid roller cam and 600LB+ open pressure and had no problems at all. In fact these rockers are probably 20 years old and were in my street engine with a large solid cam for years also. Also using Precision Oil Pumps shafts and strands; all work and fit perfectly.