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Deburring the rockers - metallurgy question


TimZ

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Okay, so this is what happens when I have to wait around for the machinist...

 

My head is off to the machinist getting its new valvetrain, and I've been going over the rest of the pieces here. As it turns out, there was some amount of interference between the rockers and the valve spring retainers - the "lip" around the lash pads was a bit too high for the pad and left witness marks on the underside of the rockers. Nothing horrible, but the marks were there nontheless.

 

I started out by just polishing out the marks, but I just can't stand to do anything halfway, so I went ahead and deburred and polished the entire rocker (yes, I stayed away from the contact surfaces). I have heard of this being done before, so it seemed like a good idea at the time.

 

Of course, now I'm second-guessing myself. Specifically, I'm concerned that I may have polished away any surface hardening that might have been done on the rockers. Originally, I didn't think that these parts were hardened, and it certainly didn't put up much of a fight to my dremel, but now I'm not sure. Anybody know whether these things were surface hardened?

 

I checked with a local outfit about nitriding the rockers, and that wouldn't be terribly expensive, but they were concerned that this would make the rockers too hard.

 

Soooo - two questions...

 

1) Were the rockers originally surface hardened (aside form the contact pads)?

 

2) Regardless of 1), is it a good idea to have these rockers hardened via nitriding?

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I did mine several years ago and I have been beating them mercilessly ever since. Here are some pictures of mine (polished, lightened and radiused vs stock)

 

Cool - I was hoping maybe somebody else had done this successfully. So it also sounds like the nitriding idea is not necessary, and possibly not even desirable - that's ~$100 that I don't have to spend...thanks! :mrgreen:

 

Dragonfly - those look pretty similar to what I did (I'm going to do one more "fine" cleanup pass):

rocker2.jpg

rocker3.jpg

rocker4.jpg

 

You went quite a bit more aggressive on the tip radius than I did - it's nice to know that that worked -I'll try the same - thanks for the pics.

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You could put that amount of work in another area of the engine, and get much more responsive results IMHO.

 

No debate here - as I said, I had to touch them up anyway and one thing led to another. I have no illusions that I'm going to see any measurable results from this. Getting rid of possible stress riser starts seemed "directionally correct", that's all.

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TimZ- I've done the same to my rockers as well. I never took pictures, but you're on the right track. I've seen fairly high power and constant trips to 8000rpm without any issues.

 

1fastZ- You're correct in that the time spent elsewhere may be more benificial, but as a Z owner, I've always felt that the attention to detail in a build is what makes one car stand out from another. I know you understand what I'm saying because you are/have built a monster yourself. These little things to a guy like me, just can't be over looked, regardless of how much time is invested.

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Tim, I have done rockers like you did, the bodies were forgings from what I was told, and you just wanted to clean up the stress risers, and lighten the reciprocating end of the unit.

 

These are very similar to Honda Rockers used in the 70's, and by lightening them the valvetrain stability with the stock springs was increased quite dramatically. Matter of fact, a set of rockers I lightened and polished in a 3Y 250CC Single OHC Honda went through three engines...owner kept swapping the cam and rockers from engine to engine!

 

You just want your polishing marks to run longitudinally, and not across the beam.

 

I recently had an opportunity to look at some cut apart pieces, and Nissan Surface Hardening goes deeper than most would think... But these rocers are Forged, so you're O.K.

 

Looks Good. You can take a look at Mile's Setup, and take some more off the reciprocating end, his look a lot like what I reprofiled on the Hondas, and a few L's back in Japan.

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TimZ- I've done the same to my rockers as well. I never took pictures, but you're on the right track. I've seen fairly high power and constant trips to 8000rpm without any issues.

 

Thanks - that's good to know.

 

...I've always felt that the attention to detail in a build is what makes one car stand out from another. ...These little things to a guy like me, just can't be over looked, regardless of how much time is invested.

I can't imagine what you're talking about... :mrgreen:

Really there isn't much else for me to be doing right now - the head is at the shop, and the rockers were here - wanted to feel like I was doing something.

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Tim, I have done rockers like you did, the bodies were forgings from what I was told, and you just wanted to clean up the stress risers, and lighten the reciprocating end of the unit.

 

These are very similar to Honda Rockers used in the 70's, and by lightening them the valvetrain stability with the stock springs was increased quite dramatically. Matter of fact, a set of rockers I lightened and polished in a 3Y 250CC Single OHC Honda went through three engines...owner kept swapping the cam and rockers from engine to engine!

 

You just want your polishing marks to run longitudinally, and not across the beam.

 

I recently had an opportunity to look at some cut apart pieces, and Nissan Surface Hardening goes deeper than most would think... But these rocers are Forged, so you're O.K.

 

Looks Good. You can take a look at Mile's Setup, and take some more off the reciprocating end, his look a lot like what I reprofiled on the Hondas, and a few L's back in Japan.

 

Also really helpful - thanks guys!

It's really nice to hear this stuff, and not have to have that nagging feeling like maybe I shouldn't have done that...

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  • 1 month later...

Okay... I've got the rockers in what I believe are pretty good shape, and the levered weights are dialed in as close as I can get them (appears to be within 0.1g at 31.8g each). Here's a pic:

rockers.jpg

 

Since this thread started, I noticed that Kameari sells their own lightweight chromoly rockers. I tried to mimic the shape of these rockers to some extent, but didn't go to quite as far as they did.

 

Interestingly, they mention a"lightweight rocker arm" in their comparison table, implying that it is a lightened version of the stock piece, and give the overall weight at 60g. I took quite a bit a material off of mine and they still weigh in at ~72g total, which is only ~4g lighter than stock. I can't even imagine taking another 12g out of them :shock: (although they do mention that the "lightened" rockers failed at 3 metric ton load). Anybody have any idea of what these are and/or how the weight reduction was achieved?

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I don't think those are modified stock pieces. There are three cast letters on the side of the rocker (looks like "KEW" = Kameari Engine Works?) that are not found on stock pieces. Those letters are above the surface reather than under the surface so the letters are not carved. I would bet they are new pieces. There is only one way to know for sure how they did it...you order some...and then let us know :)

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I don't think those are modified stock pieces. There are three cast letters on the side of the rocker (looks like "KEW" = Kameari Engine Works?) that are not found on stock pieces. Those letters are above the surface reather than under the surface so the letters are not carved. I would bet they are new pieces. There is only one way to know for sure how they did it...you order some...and then let us know :)

 

Come to think of it, I think you are correct. I can tell once I enlarge the pic, its got a shape of its own. Its quite different in shape.....

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I don't think those are modified stock pieces. There are three cast letters on the side of the rocker (looks like "KEW" = Kameari Engine Works?) that are not found on stock pieces. Those letters are above the surface reather than under the surface so the letters are not carved. I would bet they are new pieces. There is only one way to know for sure how they did it...you order some...and then let us know :)

 

That's correct - the one in the picture is made by Kameari. However, if you look in the comparison table on the side, there are three different rockers being compared - stock, "lightened", and the Kameari piece. I'm wondering what that middle one is...

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They will round off the lever end quite a bit when reducing weight on the reciprocating end. Nowhere near as square as yours are.

 

But the Kameari Rockers are their own forging. They make High Strength S30 Axles as well... They make all kinds of cool stuff.

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That's correct - the one in the picture is made by Kameari. However, if you look in the comparison table on the side, there are three different rockers being compared - stock, "lightened", and the Kameari piece. I'm wondering what that middle one is...

 

really? you sure you didn't just miss the three casting letters and think the KEW ones are modified pieces? :)...I kid, I kid.

 

Anyway, you can take off material here or there but what Kameari shows is how modifying stock piece to 60g results in breakage in the strength test. In contrast, the 57g KEW pieces are lighter and passed the strength test. That's how they boast superiority, but it's their ad...

 

*cough*titanium valves*cough*

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