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, and 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.