Pushrods scored by guides

[anwat]

You are looking at brand new pushrods with about 30 minutes of idle time on them. Was this wear caused by the rockers being too loose? It's clearly rubbing on the guides, but I'm not understanding what I did wrong. The only issue I had was the rockers had loosened up on the passenger's side by the time I finished adjusting the driver's side. I noticed some of the nuts on the rockers were kind of loose when I put them on. I used new rockers, nuts and rods on everything. In the second photo, I've replaced all the intake rods (they were the only ones with the scoring) did the cold lash and made sure the rods are in the center of the guide with a feeler gauge. Once it was all tight, I went along an put a crimp nut on top, but I noticed that on some of the studs, I could install the crimp nut with my fingers all the way down to the rocker nut. That doesn't seem right, and it doesn't seem like it's going to prevent that nut from backing out again.
So here's my questions: Can the threads on those rocker studs wear to the point the nuts won't be tight enough to hold? They aren't backing out, the nuts just aren't tight, even the prevailing torque nuts are only finger tight on many of them. And second, is that wear on the rods typical of a loose rocker? By the time I got back over to the passenger's side, there were several rockers that were already loose and I could hear the valves.
Replace the studs? Get Polylocks for the rockers? Or is it something I'm not doing right? Unless I'm way off, the old rocker nuts are actually tighter than the new ones that came with the rockers.

 

[Cucv_M1008]

@folkenheath

 

[folkenheath]

Guideplates require hardened pushrods made for use with guideplates, if you used a low end pushrod it likely isn't hardened and that's what can happen.

Hardened pushrods should fix that assuming the guideplates aren't too small or something but you would know that when you install them if they don't slide freely.

As far as the nuts loosening usually the nut wears out not the stud. If the new nuts are loose I would use better quality nuts or use poly locks.

 

[anwat]

Makes sense...The guideplates were there, as were the studs. I just changed the rockers and rods, and I don't think the rods were hardened. I did order the intake and exhaust from different vendors, so maybe the exhaust rods were hardened and the intakes weren't, but only the intakes were scored. I was thinking if the rocker got loose enough, the rod would be able to move to the side and scrape the guideplate. Would the machine shop remove the guideplates and studs when they did the valve job? Maybe they put them back in a slightly different place? Point taken about the quality of parts, it's a frequent topic here. I just found it odd that probably 10 of the 16 prevailing torque nuts can be screwed on to the studs with my fingers...but I guess the only option is to get polylocks at this point.

 

[Blue85]

It seems like those pushrods are going to wander side-to-side at least a little bit, based on idle-redline, temperature, etc. Some engines don't have them, so why are they required? It's not intuitive that they should be grazing the rods all the time, especially while idling, it seems like they should be more of a backup. Is there more than one thickness of pushrod or more than one thickness of guides? Otherwise, the rockers must be free to move more than they should.

 

[sweetk30]

And dont forget pushrod guide plates need to be set up correctly.

 

[folkenheath]

Makes sense...The guideplates were there, as were the studs. I just changed the rockers and rods, and I don't think the rods were hardened. I did order the intake and exhaust from different vendors, so maybe the exhaust rods were hardened and the intakes weren't, but only the intakes were scored. I was thinking if the rocker got loose enough, the rod would be able to move to the side and scrape the guideplate. Would the machine shop remove the guideplates and studs when they did the valve job? Maybe they put them back in a slightly different place? Point taken about the quality of parts, it's a frequent topic here. I just found it odd that probably 10 of the 16 prevailing torque nuts can be screwed on to the studs with my fingers...but I guess the only option is to get polylocks at this point.

Yes they should remove them for machining to make sure everything is clean after, but its not required to fit in some machines. Also, they can be moved around before the stud is tightened to center the rocker tip on the valve stem. I like to leave them barely loose, mockup the rockers, and move them around with one hand to center them, then use the other hand to remove the rockers so I can hold them guideplate from moving and snug it down. In fact I like to use the Dart 2 piece guideplates on the BBC because its often not possible to get them centered perfectly on both valves in the pair with 1 piece guideplates, although I am rather picky about it because it's usually for an aftermarket cam with higher lift.

I usually recommend 1 piece chrome moly pushrods that don't have the separate ball ends that could potentially come off and cause problems, they are also hardened. But for a more stock application the aftermarket does sell 3 piece hardened pushrods that can work fine.

It seems like those pushrods are going to wander side-to-side at least a little bit, based on idle-redline, temperature, etc. Some engines don't have them, so why are they required? It's not intuitive that they should be grazing the rods all the time, especially while idling, it seems like they should be more of a backup. Is there more than one thickness of pushrod or more than one thickness of guides? Otherwise, the rockers must be free to move more than they should.

The engines that don't have guideplates use some other form of alignment, such as self aligning rockers, or shaft rockers that can't move side to side, etc. The BBC has angled pushrods due to the canted valves, so it could cause wear faster without hardened pushrods. But an alignment feature is certainly necessary so the rocker tip doesn't come off the valve stem and hit the retainer, which can be catastrophic if you drop a valve or just cause premature wear from riding toward one side.

 

[anwat]

That's almost exactly what the engine builder that I trust told me. I finally broke down and swallowed my pride and went over and talked to him about all this. He said definitely need hardened pushrods, he also recommended one piece, which are ordered. He said when reassembling, use a feeler gauge to center the rod in the guide plate, then snug everythig down, check one more time, then tighten the studs down. He added that the stock guideplates like I have are made of a soft metal, whereas many of the aftermarket pates are harder and can really do damage in a short amount of time, so he always uses the stock plates if possible. He said the loose rockers contributed to the problem by allowing the rods to move side to side and not stay in the pocket in rocker. Given enough time, one would have shot right through the valve cover if I would not have heard the loose valvetrain.
He agreed that the parts out there are crappy. I told him I had used brand new nuts that came with the rockers, and he wasn't at all surprised they were loose. I asked about changing the studs out, he said even if they were worn, still better to use polylocks than the nuts that came with the rockers. So, polylocks ordered. Amazing to me that in a market as big as L.A., no one stocks any of these parts...everything is coming from some other state. Tells you something about our communist state government. But I digress. Being an engine builder, he of course recommended gettting rid of the guide plates and going with a full roller cam and valvetrain, but that's not in the financial plan for this year.

The one question I didn't ask is what's more important, getting the rocker centered on the valve stem, or getting the pushrod centered in the guide plate. Seems one will probably have to take a backseat to the other since I don't have the DART guideplates you mentioned. I'm guessing the valve stem is crucial, and the guide plate will be OK as long as nothing's touching, correct?

 

[sweetk30]

we need @4X4HIGH back on the page just for info .

 

[folkenheath]

That's almost exactly what the engine builder that I trust told me. I finally broke down and swallowed my pride and went over and talked to him about all this. He said definitely need hardened pushrods, he also recommended one piece, which are ordered.

I agree

He said when reassembling, use a feeler gauge to center the rod in the guide plate, then snug everythig down, check one more time, then tighten the studs down.

Using a feeler gauge to center the rod in the guideplate would be a waste of time because as soon as the engine is running the pushrod is going to rub on one side more than the other under load, plus there should not be much room at all, you would need two .002" feeler gauges or something. You want to move the guideplate to center the rockers on the valve stem before you tighten down the stud. With the rockers sitting there as you move the guideplate you can watch the tips move. You can also wiggle the rockers a little with your other hand to see how much they can move either way, this helps you better center them on the valve stem to make sure they can't get too close to one side.

He added that the stock guideplates like I have are made of a soft metal, whereas many of the aftermarket pates are harder and can really do damage in a short amount of time, so he always uses the stock plates if possible.

I prefer the Dart plates because of the adjustability, the hardened pushrods will work fine with either and non hardened pushrods will get ruined by either.

He said the loose rockers contributed to the problem by allowing the rods to move side to side and not stay in the pocket in rocker. Given enough time, one would have shot right through the valve cover if I would not have heard the loose valvetrain.
He agreed that the parts out there are crappy. I told him I had used brand new nuts that came with the rockers, and he wasn't at all surprised they were loose. I asked about changing the studs out, he said even if they were worn, still better to use polylocks than the nuts that came with the rockers. So, polylocks ordered. Amazing to me that in a market as big as L.A., no one stocks any of these parts...everything is coming from some other state. Tells you something about our communist state government. But I digress. Being an engine builder, he of course recommended gettting rid of the guide plates and going with a full roller cam and valvetrain, but that's not in the financial plan for this year.

A full roller cam and full roller rockers will still not get rid of the guideplates. To do that you would need a set of shaft rockers, or some of the later model self aligning rockers that have little guides on the rocker tip that trap/glide the side of the valve stem, and I do not recommend those as they could side load the valve stem. Shaft rockers are the best, but not necessary for even most street performance builds, the guideplates with hardened one piece pushrods are the recommended option for that.

The one question I didn't ask is what's more important, getting the rocker centered on the valve stem, or getting the pushrod centered in the guide plate. Seems one will probably have to take a backseat to the other since I don't have the DART guideplates you mentioned. I'm guessing the valve stem is crucial, and the guide plate will be OK as long as nothing's touching, correct?

You can't really get the pushrod centered on the guideplate, there is a very small gap and the pushrod is angled, so it will rub on the guideplate as soon as you start it, that's what the guideplate is for. Just make sure the pushrods slide through the guideplate without binding before you put the rocker on, or you need to replace the guideplates if they are bent or something and pinching the pushrod. They should slide free with very minimal slop and of course match the diameter, you need to use a 3/8" guideplate with a 3/8" pushrod to achieve that. Then you should focus on getting the rockers centered on the valve stems.