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thoughts on broken roller rockers

8K views 45 replies 21 participants last post by  Kingfish999 
#1 ·
so i apparently bought a set of knockoff Miller Mid-Lift rockers and 6 of them have the trunnions broken in half where the stud goes through. there only about a eyar only with only a few thousand miles on them. i went ahead and ordered a new set since its a daily driver but was wondering if i used these on a build that may get used only a a few times a year with a very mild cam if it would be alright.

 
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#2 ·
I'm certainly not an expert like several members here are, but here is my take on the situation:
-you mentioned knockoffs. You get what you pay for.
-you need to do some hard looking and make certain you don't have clearance issues that will continue to break rocker arms.
 
#3 ·
How much did you pay for them? Now take that X2. Now how much have you paid for them? Amazes me that people can not (will not?) afford to do it right, but they can afford to do it over and over and over again....lol
 
#5 ·
i didnt know they were knockoffs till i emailed Miller last night and he pointed out that they are knockoffs that use cheap trunnions.

The trunnions in your rocker arms are NOT our trunnions. They've been replaced for a cheap offshore version by an "X" distributor of PVS rockers, and unfortunately, we have had to sell numerous buyers of these with the same product who thought they were getting a "deal" buying them for $225 or $275, or whatever. The trunnions in your rockers are SOLID (not gun-drilled); made from an inferior steel compared to the 8620 Bizmuth Aerospace steel we use; and lastly, don't have the double-flat on each side of the stud mounting hole which eliminates the sharp edge on the bottom of conventional trunnions. Even the few rocker manufacturers who "edge-break" that sharp bottom side of their stud hole, are not accomplishing the increased benefit of a full flat that has a "bevel" on the ID of the hole to be sure there's no chance of a stress-riser developing. The gun-drilled hole is NOT for lightening, it is for strength, just as with gun drilled axles. Having two surfaces to a diameter for case hardening heat treat is much stronger than one, where a solid trunnion will have a soft core that provides no strength, only weight.
 
#7 ·
So I bought a set from some guy named paul (I've seen him post around), he was selling them on ebay and said they were actual mid lift rockers miller lifters. when I got mine, one was missing a clip on the trunion. He sent me a new set. I never ended up using them and they are sitting on the shelf.

What does double flat mean on the trunion, flat on the nut side and flat on the head side?

I guess mine are fakes too? How do I find out?
 
#8 ·
thats how i got mine. i got them from someone on here who sent me an ebay link. i dont remeber who it was because i cant find anypost or PM in my profile relating to it. the ebay seller was called high_flow_dynamics which is no longer on ebay. they were normally 300$ but were on sale for 200$ when i bought them, they also had others for chevy and big blocks so i thought it was legit. unforunatly not

from what Miller told me, one of the ways to tell is the trunnion will have a flat side on the top and bottom. mine and probably yours will only have one flat side. heres a pic of the double sided trunnion
 
#16 ·
Hmmm...sometimes, as in my case, I purchased them before the quality and suitability were able to be determined. Paul was a stand up guy and offered a refund before I even uttered the words. This is sometimes referred to as customer service and includes return policy, answering emails, having a phone, etc. thanks for your addition to this thread, I've learned a new phrase.
 
#18 ·
ask•hole [âšk-hølę] NOUN, proper

Commonly referred to as Ed Curtis

Anyhow Paul did refund my money, took phone calls, and returned messages.

Had a thread like this existed or another was easily accessible I may have known ahead of time.

Ed am I living rent free in your midget, dwarf brain? Please don't bother trying to attack me any longer. It isn't worth the calories you burn being an internet bully.
 
#22 ·
I have two sets of Miller Rocker arms and his shaft rocker set up. I have never had a problem with them and one set came from Paul Kane several years ago. They have the Miller trunnions. As I recall Paul was affiliated with High Flow Dynamics. But I could be wrong. If you click on the link for HFD and go to specials you will see Miller SBF Rocker Arms for sale If you look at the description they clearly note that the trunnions are not Miller.
Apparently Something Changed and Jim Miller is not able to stop it. They don't indicate that they are Xdistributors quite the contrary.

www.highflowdynamics.com/

We are a distributor of Miller Rocker Arms and are pleased to offer the 7075-T7 Aircraft Aluminum Small Block Ford rocker arms at absolute bargain pricing.

Miller SBF Roller Rockers (same manufacturer as the $3400 Miller Boss 429 hemi rocker arms)
Designed exclusively for small block Windsor motors (289, 302, 351W, etc.)
Rocker body made of 7075-T7 aircraft aluminum
8620 billet steel trunnion axle. This is a beautiful solid trunnion with a single flat, not the Miller rifle-drilled trunnion.
Beefy oversize pin on roller tip
Tiny pushrod cup oiling hole so as to help control top end oiling
Chromoly hammer-forged polylocks (ie work hardened, not broached)
Establishing proper pushrod length is a snap with the top measuring face on the rocker (instructions included).
Available in 1.6 ratio or 1.7 ratio, 7/16" or 3/8" rocker stud
Complete brand new rocker arm package with 16 rocker arms and chromoly polylocks and instructions.
Original manufacturer price was $384 Retail/$342 Racer Net
302-351W standard valve layout rockers, $298/set
N351 & Z304 0.150" offset valve rockers, $328/set
Yes, we ship international.


Questions?
You can e-mail us at:
highflowdynamics@earthlink.net
 
#24 ·
8620 billet steel trunnion axle. This is a beautiful solid trunnion with a single flat, not the Miller rifle-drilled trunnion.
so they're 'Miller' rockers without 'Miller' trunnions. my head says that makes them no longer Miller. there modified and not for the better AKA cheap knockoff

well now that i know they still sell them maybe i can get some kinda warranty for them and at least have a set of non-broken rockers i can use in my offroad truck. with mild cam and very little use, they should at least last awhile. till the engine blows up at least, its been though 4 so far. im hard on my toys lol
 
#37 ·
so they're 'Miller' rockers without 'Miller' trunnions. my head says that makes them no longer Miller. there modified and not for the better AKA cheap knockoff
Its more of a standard line vs an economical line. I would blame poor advertising. Most people don't have a problem with cheaper poor quality and more expensive better quality as long as they are aware of it.

I would't get to excited over the solid Trunnion. Crane and many other manufactures use them. Maybe you have a problem that is causing them to split? A shame to see a really nice product get trashed.
Hard to compare unless you know the material, diameter(s), and design.

You only say that because you've never manufactured roller rockers. Making crappy ones is about the same cost as making good ones. Incidentally, there's no money in it. 99% of the buyers think they should cost 149.99.

I'd start by lookin for anything that resembles valve float. Think about the loads on the trunnion. There pretty much aren't any, other than the spring load.
I've been a manufacturer and buyer of parts and know both the supplier wants to make as much as possible and the buyer wants to spend as least as possible, so both could be to blame.

Valve float can break all kinds of stuff, so can poor manufacturing and engineering practices. Agree, parts fail just as much because of the assembler, the end user, or the manufacturer. If you have more parts failing than comparable parts made by the competition there is a problem.
 
#29 ·
well i dont know much about quality of specific parts. High Flow Dynamics and Miller are both trying to make money on thier products and they seem to use the same arm itself. Miller is selling theres for like 480$ a set and High Flow has them on special for 298$ and mention theres not using the Miller trunnions, makes me think that Miller is probably the more quality product or he is making a heck of a profit per set. for Miller to say that hes seen several of these and knew right away that they were not his from as little info as i given mean it might actually be a somewhat common on an issue.

im not sure exactly what conditions would break a trunnion in half unless there was jsut that much resistance or binding. the pushrods and guides show practuicly no wear. the valve stems and roller tips didnt have any wear. my cam is making 0.544/0.555 lift on AFR heads that should should handle plenty more lift. its on a hydrualic lifters and not seeing rpms higher than 5k. i measured the pushrods the the mid-lift procedure with IIRC turnes out to be about 0.200" longer and required longer 7/16 studs also. anything else i should check?
 
#30 ·
well i dont know much about quality of specific parts. High Flow Dynamics and Miller are both trying to make money on thier products and they seem to use the same arm itself. Miller is selling theres for like 480$ a set and High Flow has them on special for 298$ and mention theres not using the Miller trunnions, makes me think that Miller is probably the more quality product or he is making a heck of a profit per set. for Miller to say that hes seen several of these and knew right away that they were not his from as little info as i given mean it might actually be a somewhat common on an issue.
You only say that because you've never manufactured roller rockers. Making crappy ones is about the same cost as making good ones. Incidentally, there's no money in it. 99% of the buyers think they should cost 149.99.

im not sure exactly what conditions would break a trunnion in half unless there was jsut that much resistance or binding. the pushrods and guides show practuicly no wear. the valve stems and roller tips didnt have any wear. my cam is making 0.544/0.555 lift on AFR heads that should should handle plenty more lift. its on a hydrualic lifters and not seeing rpms higher than 5k. i measured the pushrods the the mid-lift procedure with IIRC turnes out to be about 0.200" longer and required longer 7/16 studs also. anything else i should check?
I'd start by lookin for anything that resembles valve float. Think about the loads on the trunnion. There pretty much aren't any, other than the spring load.
 
#31 ·
Kingfish999,

Are your JM Rockers designed for 3/8" or 7/16" rocker studs?

I remember when I installed mine (JM 1.7 3/8") during lash rechecking, I noticed some of the polylocks didn't seat fully on the trunnions. They seemed to wide and were hung up against the body of the rocker. The bottom edge of the polylock actually started to shear as I unthreaded them. Paul sent me a few replacement polylocks and stated someone missed the final cage bearing alignment during the last step of manufacturing. In the end, I reused the thinner polylocks from my old FMS rockers.

I'm wondering if perhaps you might have ran into the same issue. Also, have you looked into replacement trunnions yet? They don't look to hard to change with a tool that Comp sells that use can use in a bench vise.
 
#36 ·
Guess I was lucky when I ordered mine like, oh gosh, 15 years ago? Still going strong...about 10,000 passes down the strip later and on a slew of different engines, all solid rollers.

But this has been an interesting thread. Thanks Mark O'Neal and of course Ed for his wit.
 
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