You talk about rocker arm life, but then I wonder how many dyno sessions or laps my Jessel rocker arms made in their life prior to me only using them 9 sec at a time. I actually had my Jessel rocker arms rebuilt during my engines downtime following our wheel stand episode.
Broken rocker arms two weekends in a row
- Thread starter Les Gibson
- Start date
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The first rocker that broke (#4 exhaust) broke on launch, as soon as the transbrake released. I have launch RPM set at 3800. The engine had been warmed up prior to making this run. The second rocker (#5 exhaust) broke shortly after initial launch. However, on this run the car made a hard right turn (something it has never done before) so I got out of the gas until I got the car straightened out and then I got back on the gas while still in 1st gear (powerglide). The rocker broke soon after getting back on the gas and may be due to my pedaling of the throttle. Again the engine had been warmed prior to the run. I shut off the engine immediately, thru it in neutral and coasted down the track and got towed back to my trailer.
I've checked all the clearances, nothing is binding or hitting, no evidence of any valve to piston contact.
These days, who makes steel rockers for Mopar Performance aluminum W5 heads? I would love to have Norris rockers on this engine, but even if you can find a set I don't want to have to mortgage my house to get them. Valve springs were installed new this spring.
Who makes steel roller rockers for Mopar Performance aluminum W5 heads these days?
Do you have a picture of the sweep pattern on top of the valve , that can uaually tell a story .
no, I didn't thing to take a picture of that.
T&D, But I bet they are 3200.00 depending on the roller options.
Inertia
Well-Known Member
If you can't get rockers, can you get bushes made like leaf spring rubber bushes with a shoulder, to insert where the bearings are.
That'd spread stress, - or some variation thereof ?
Spitballing .
That'd spread stress, - or some variation thereof ?
Spitballing .
If it was me I would double check your geometry and simple stuff so you know it isn’t on you. Getting off and on the throttle did not cause this because that’s what racers do. If you would hear my son at the finish line and every other good racer you know that. Our season is almost over now so I would talk to the Mopar guy at Harland Sharp (I forget his name) and I would box them up and send them to them for testing. Both being exhaust rockers makes me go hmmmm.
67mprfan
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I believe they offer a rebuild service, or an inspection service from what there website says
Hi John,
Yeah, I didn’t think that would have caused it to break. I put a call into Randy at HS and am waiting for him to call me back. I gave the broken rocker arms to the gentleman I bought the Arrow from as he is a machinist by trade and wanted to do some testing on them. His findings are no fretting or stress cracks in the aluminum. His opinion is they’ve just reached the end of their service life and should be replaced, at least the exhaust rockers.
It’s NA, no power adders. Holley tunnel Ram with dual 850ish carbs
Retainer to guide? I'm sorry. I'm not like the others. I refuse to believe they are breaking "just because" they're aluminum. Harland Sharp makes some of the best rockers in the world. I believe you have something wrong somewhere. Well not "you" but you understand what I'm saying.
And this is on a crazy fast engine with probably .900 lift or so.
As many millions of engine been built with aluminum rockers, we'd see a much higher failure rate I do believe if it was the aluminum.
pink340swinger
Well-Known Member
I had something similar happen to me last weekend. .982 lift and 9800rpm. Only the second time I've broken a rocker arm.
Notice two things about the broken alum rockers in this thread?
Both brands broke in the same place, right where the load is greatest.
In the break area, both rockers are much thicker than comparable steel rockers...but not thick enough.
Both brands broke in the same place, right where the load is greatest.
In the break area, both rockers are much thicker than comparable steel rockers...but not thick enough.
We're your rockers cryo treated? Im thinking about having some parts cryo treated and am just curious.
Jeremiah (jd)
Well-Known Member
My error. Racing Thurs-Sat has destroyed my brain. Any chance you can find a used Jesel paired shaft setup for a W5? Being a b motor guy I don't follow the parts availability of the LA world.
Calling T&D or Jesel always comes with sticker shock which is why I suggested a used setup. I'd imagine that might be hard to come by.
LMAO @Jeremiah “Brain destroyed racing.” I hope the day was good for you at least.
@Les Gibson
Have you called TD or Jesel?
The valve springs are fresh?
How much clearance is available at the valve and piston?
Following along!!!!
I hope you get this figured out Les.
I've been on their websites looking at what each offers for small block mopar W2/W5 heads. T&D has a nice set up but it requires machining the heads and modifying the oiling system to feed through the push rods and I really don't want to go through all of that expense coupled with the cost of the rocker set up. Jesel's also require machining of the heads. The gentleman who I bought the Arrow from this past spring, and also the engine builder, is a machinist by trade and he tested the broken rockers and found no fretting or stress fractures in the aluminum. So that information, coupled with speaking with Randy, Jr. at Harland Sharp, indicates that these rockers are probably at the end of their service life. There's been a lot of questions about spring pressure, 655, and cam lift, .685. Both of those specs are well within the tolerance of these HS rockers. So long story short, got a set of new exhaust rockers to replace the ones currently on the engine to finish out the last 3 or 4 weeks of the season up here in Maine, then during the winter come up with a new plan.
no clearance issue with retainer to guide either.
nope, John, just a modest .685 lift cam with spring pressure at 655.
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