Dang Rocker Shafts Too Soft

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nm9stheham

nm9stheham

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Sometimes you take a chance and it does not pan out. We were replacing an erratic lifter last night and pulled the rockers to inspect and found this wear on the rockers shafts after approximately 1000 street miles. The needles are digging into the shafts big time; this pix is one of the worst areas, but they all show some wear and edges on the areas where the needles ride on the shaft.

The 'chance' here was some PRW AL rockers on eBay for $224. I saw them, and said "what the hey; let's see if we get away with it" LOL. These were leftovers from PRW (and shipped from the PRW address), and when received, looked to be broken sets put together into complete sets. Who knows what shafts got thrown in, but obviously they are nearly not up the required hardness. I have read that is a key factor in the success or failure of needle bearing rockers.

We got some Crane Gold 1.6 rockers on the way. They look to be discontinued but Jegs has some SBM 1.6 sets left. With the way that stock rockers run and last, you would think that custom rockers would be easy to make work well.....

DSCN1443.JPG
 
I am dealing with EXACTLY the same thing with PQ rockrs on a 440, a rocker jamnut/adjuster broke, baked off and the pushrod and damaged the rocker, now after waiting 2 months for the rocker, the shaft was so worn I had to literally tap the rockers off/over the ridges in the shafts.. I didn't have a camera, but previous post above pix very similar.

This motor doesn't have 20 hrs, and uses the questionable allen adjusters as well.

Thankyou @crackedback, for recommending Hughes
bushed shaft rockers, to be on order..





Will post pix later..
 
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Are you sure that's not from lack of oil?
 
A needle bearing has no place riding on a rocker shaft IMHO. You would be WORLDS ahead with a bushed rocker, or even a plain aluminum rocker. If you think about it, almost ALL the load is on 1 or maybe 2 little tiny rollers, with a limited amount of movement, and NO rotational movement.
 
dano said:
Is that a needle bearing or Bushing on the rocker?
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Have to be needles with that kind of wear. Needle bearings require very round, hard shafts. That is why they cost so much. OEM malleable iron rockers last forever. I have a set we are going for 500K with 273 solid lifters.
 
replicaracer43 said:
A needle bearing has no place riding on a rocker shaft IMHO. You would be WORLDS ahead with a bushed rocker, or even a plain aluminum rocker. If you think about it, almost ALL the load is on 1 or maybe 2 little tiny rollers, with a limited amount of movement, and NO rotational movement.
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But you get 8 to 12 horsepower on a Pro stock or NASCAR engine. ;-)
 
inertia said:
Good oil/p by a known good guage, and lotsa oil in the V/Cs. It does have solids, so valve noise is a given (16/18).
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What I meant is, even with good oil pressure, that area is not immune to oil starvation.
 
As mentioned above, load distribution way superior with bushings and if you have stout springs I wouldn't go any other way. Very little energy loss in rocker arm friction anyway.
 
I agree about the needle bearings. I hate them in this application, but even still, it seems if they were getting oil properly, this wouldn't have happened.
 
Now roller tips is another story and serves an important purpose in extending the life of valves, seats and guides.
 
Damn..going cheap will always eventually bite you in the ***...
 
replicaracer43 said:
A needle bearing has no place riding on a rocker shaft IMHO. You would be WORLDS ahead with a bushed rocker, or even a plain aluminum rocker. If you think about it, almost ALL the load is on 1 or maybe 2 little tiny rollers, with a limited amount of movement, and NO rotational movement.
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Looks like about 6 or 8 needles.
 
Hey RRR, these are the rockers that we modded to add oiling holes to the valve tops and we checked the oil flow carefully, at least while static and priming. It was oozing out between each rocker side so the bearings are getting oil , and the sides of the bearing assemblies are tight to the shafts to help retain oil in place. And the p-rod cups look perfect and they get as high or higher loading psi-wise than the needles. Valve tips are untouched as are the main rollers, and again, that is a high pis loading. Oil used was Brad Penn 10W30 throughout this 1000 miles.

For added oiling, the one thing that might help is to open up the hole in the rocker shaft where it meets the pedestal; on these shafts, that hole is much smaller than stock and it the main restriction for oil coming into the interiro of the shaft. I called PRW about this before installation, and they said it was the way it should be, so I assumed they restricted oil flow there just to keep it from going all over the place in excess amounts.

But buckets of oil won't overcome too soft a shaft material. I had read up on needle roller bearing issues before installing these, and the possible issues with insufficient hardness or depth of hardness, on the shafts, was the one common theme for problems in shaft rocker apps. And if you look into needle bearing engineering in general, that is a constant theme in all needle bearing usage. The load concentration is very high so the matching surface has to hold up to it.

Obviously, if Harland-Sharps are lasting OK, then they know how to get the shaft surface hardness to the right level. And just as obviously, bargain basement eBay specials are a matter of luck!

Well, if anything, it was a not too expensive experiment and it may help others see one potential issue of needle bearing rockers.
 
OBTW, spring loading is nothing out of the ordinary here: around 120 closed and just under 300 open.

And I am not knocking PRW. These were seconds in some fashion or another (the eBay seller said he got them in a closeout as a big batch), so again, who knows if some wrong shafts got put into the box that we received.
 
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Nothing wrong with quality needle bearing rocker arms. T&D uses needle bearings. Jesel uses needle bearings. We've run several sets of Harland Sharp full roller rockers on quite a few engines & never had any problems. Yes you have to use hardened shafts, but they worked well. If there are oiling issues you will ruin any rocker arm, bushed or bearing.
 
nm9stheham said:
Sometimes you take a chance and it does not pan out. We were replacing an erratic lifter last night and pulled the rockers to inspect and found this wear on the rockers shafts after approximately 1000 street miles. The needles are digging into the shafts big time; this pix is one of the worst areas, but they all show some wear and edges on the areas where the needles ride on the shaft.

The 'chance' here was some PRW AL rockers on eBay for $224. I saw them, and said "what the hey; let's see if we get away with it" LOL. These were leftovers from PRW (and shipped from the PRW address), and when received, looked to be broken sets put together into complete sets. Who knows what shafts got thrown in, but obviously they are nearly not up the required hardness. I have read that is a key factor in the success or failure of needle bearing rockers.

We got some Crane Gold 1.6 rockers on the way. They look to be discontinued but Jegs has some SBM 1.6 sets left. With the way that stock rockers run and last, you would think that custom rockers would be easy to make work well.....
Click to expand...

Would buying a set of good shafts, like Harland Sharpe, salvage the rockers? Definitely would have to go through everything and clean everything up. People run needle bearings on shafts all the time. You just have to do it right. Cheap never works for me.
 
66fs said:
Would buying a set of good shafts, like Harland Sharpe, salvage the rockers? Definitely would have to go through everything and clean everything up. People run needle bearings on shafts all the time. You just have to do it right. Cheap never works for me.
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That is one thing I have thought of.... but with the Nationals coming up in <2 months, my son and I are just gonna try some known better units. Long term, I might try something with the rockers themselves with better shafts, if the needles still look OK, or see if the seller will send some better shafts.

I looked into buying or finding a Brinnell tester here locally when I got these rockers and shafts just to check the shaft hardness. If there is ever time, I might still do that. It would be one of those 'good to know' things...
 
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