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"¾ sphere" is just an artifact of how far down into the "tube" part of the rod the ball goes before it reaches the weld. If they welded it all the way up to the "equator" of the ball, it would look like a "hemisphere". Wouldn't "be" any different really, would just "look" different.
Doesn't matter in any case. The only part of the end of the PR that does any work, is the top half or so (hemisphere) of the ball. Usually less than a third of it, actually. The rest never touches anything.
Many stock push rods are 1-piece. Unlike that 3-piece pile of crap thing you have there. Most "better than stock replacement" ones (aka 1-piece) have the end swedged over. "Custom" ones could be anything, but they have to have some way of adjusting their length in between the hemispheres; so many might well be 3-piece, like the "custom" one in your pic. While still 3-piece, it's clearly better than the cheeeeeeep 3-piece type that looks like 2 ball bearings welded into a tube. The reason those are crap is because they fail easily by way of the ball getting driven down into the tube by high loads, and splitting the end of the tube open.
I think you're overthinking that specific insignificant appearance attribute somehow.
well, its difficult to see the rocker arm/push rod angle. the rocker moves by 20°. at 10° the edge of the semi-sphere just toutches the edge of the cup. as the rocker is not square to the push rod at mid-lift the half-sphere probably comes out of the cup. now we could discuss if this is beneficial (oil entrainment) or detrimental (scraping off the oil), but i think the original 3/4 spheres might be there for a reason. i know smith does the 3/4 spheres for the ls1 because i have a sample here.
also, what do you think about the smaller holes and the "texture" on the *****? is it a special coating? i have only seen polished ***** so far.
btw, the set was $550 so i strongly hope its not a "pile of crap", i just want to make sure they didn mix up the application. (of course they will say they didnt.)
well, its difficult to see the rocker arm/push rod angle. the rocker moves by 20°. at 10° the edge of the semi-sphere just toutches the edge of the cup. as the rocker is not square to the push rod at mid-lift the half-sphere probably comes out of the cup. now we could discuss if this is beneficial (oil entrainment) or detrimental (scraping off the oil), but i think the original 3/4 spheres might be there for a reason. i know smith does the 3/4 spheres for the ls1 because i have a sample here.
also, what do you think about the smaller holes and the "texture" on the *****? is it a special coating? i have only seen polished ***** so far.
btw, the set was $550 so i strongly hope its not a "pile of crap", i just want to make sure they didn mix up the application. (of course they will say they didnt.)
I barely have $550 in my short block, What kind of RPM are you turning that you need $550 pushrods!? I'm not hating I just want to know what you're building
"¾ sphere" is just an artifact of how far down into the "tube" part of the rod the ball goes before it reaches the weld. If they welded it all the way up to the "equator" of the ball, it would look like a "hemisphere". Wouldn't "be" any different really, would just "look" different.
Doesn't matter in any case. The only part of the end of the PR that does any work, is the top half or so (hemisphere) of the ball. Usually less than a third of it, actually. The rest never touches anything.
Many stock push rods are 1-piece. Unlike that 3-piece pile of crap thing you have there. Most "better than stock replacement" ones (aka 1-piece) have the end swedged over. "Custom" ones could be anything, but they have to have some way of adjusting their length in between the hemispheres; so many might well be 3-piece, like the "custom" one in your pic. While still 3-piece, it's clearly better than the cheeeeeeep 3-piece type that looks like 2 ball bearings welded into a tube. The reason those are crap is because they fail easily by way of the ball getting driven down into the tube by high loads, and splitting the end of the tube open.
I think you're overthinking that specific insignificant appearance attribute somehow.
There are quality, 3pc aftermarket pushrods out there. I believe the Smith Brothers pushrods I have are 3pc, and they certainly are NOT crap. If designed correctly, there's absolutely no way the "ball" will be pressed up into the tube......
I have sets of custom built polished 1/2” and 9/16” pushrods in the shop that didn’t cost anywhere near that. Custom made for Cup engines.
Dian, the texture on the tips of that pushrod concerns me. The female ball side of the rocker is polished, and as should be the pushrod tip. There’s a lot of wear there, even though the union is well lubricated. I feel like the textured surface would accelerate wear much faster than a typical polished pushrod tip. My humble opinion, of course…
a set of duall-taper rods will set you back up to $560 w/o shipping. at least that what im being quoted. and probably more some some longer/thick wall stuff.
yes, the texture makes me wonder. what kind of coating it is and if its proven to work. (today they texture all kinds of stuff, from piston rings to bearing surfaces, im just trying to get pertinent info on it.)
i checked out some internet offerings and indeed some of the reputable products for the ls1 seem to have swaged (just rounded off) ends. based on my impression i dont know how that works (stem hitting edge of cup?) but apparently it does.
so does it make sence to have the restricted holes in an engine that doesnt see much over 6500 rpm max?
this is a smith dual-taper on the left. it has a 1.9mm hole, stem is polished (the ones in question are a bit rough), i like it a lot, but was not able to get these.
6500 rpm and your this worried about the pushrods? Any LS engine even a bottom feeder truck engine (they all have the same valvetrain) will turn that rpm stock without breaking anything.
Getting the preload right for whatever camshaft you are running will keep you from breaking pushrods.
Both of the cars in my signature I built myself and they are turning well over 7k rpm regularly, competitively, and with $85 oem factory ls6 valve springs and $100 dollar 0.080 wall chromemoly pushrods from btr or trick flow, whatever was on sale I don't even remember.
We are just trying to understand what you are doing here
please dont worry about what im doing, it has nothing to do with the issue.
so i have definitely come to the conclusion the half-spheres are no problem (neither are the rounded off ends). the pushrod is almost square to the cup (black line in the picture) on the base circle, so it moves by about 18°. on closer inspection its no problem, my rockers have "cups in the cup" and only the inner cup toutches. the standard rockers have flared cups where the rod end is riding on an inner circle, so no problem either. i will contact trend about the coating.
so any opinions on the restricted oil holes? i have comp cams rods (3/4 spheres also) that at least have 2mm holes (original 2.3mm, trend in picture 1.5mm, smith 1.9mm). its 2.3x less area than original.
Well just going to keep trying to guess what you're doing here, at least tell us what kind of vehicle you're putting this in and what you're planning to do with it? People are more willing to help and weigh in if you're honest about your goals. Displacement? Camshaft timing? Cylinder heads? Power adder? This thread could get pretty interesting or you could make another one about what you're doing. You are clearly meticulous and you want to get everything right nothing wrong with that at all. When you come here for help you can help others too.
I was thinking about the push rod orifice diameter though and my best guess would be that a smaller diameter hole (More restrictive) would increase the oil pressure inside and around the lifter from what it would be with a larger diameter orifice. I suppose that This could improve the stability of the valve train, The trade-off being less oil volume to the rockers
Dian- Nobody is being nosey. The better mental picture of what you are doing goes a long way to understanding any perceived issue here, along with how anyone would charge $500 for a set of pushrods. Somebody saw you coming
As was said above, a MUCH cheaper set of stock pushrods will handle 6500RPM without any issue.
please dont worry about what im doing, it has nothing to do with the issue.
so i have definitely come to the conclusion the half-spheres are no problem (neither are the rounded off ends). the pushrod is almost square to the cup (black line in the picture) on the base circle, so it moves by about 18°. on closer inspection its no problem, my rockers have "cups in the cup" and only the inner cup toutches. the standard rockers have flared cups where the rod end is riding on an inner circle, so no problem either. i will contact trend about the coating.
so any opinions on the restricted oil holes? i have comp cams rods (3/4 spheres also) that at least have 2mm holes (original 2.3mm, trend in picture 1.5mm, smith 1.9mm). its 2.3x less area than original.
Restricted oiling via pushrods in an LS/LT platform is unnecessary. The idea behind restricted oil pushrods, is to limit oil to the top end in an effort to keep more oil available on the pan. The reason I feel this is unnecessary is because the oil drainback area in the LS/LT heads is massive. Gen1/2 SBC’s had a small drainback hole on either end that had to be opened up immensely in competition setups with high volume oiling, such as a dry sump pump. This scenario worked well with restricted pushrods, because oil would puddle terribly under the valve covers. This would lead to oil consumption issues and windage problems under the valve covers, much like windage issues in the crankcase. The puddling didn’t help with cooling the valvesprings, because only the bottom third of the springs saw puddling. The center 70% of the valvespring sees the most movement (heat) therefore squirters become mandatory to cool them. Hence why restricted pushrods work well in competition Gen1/2 engines. Puddling in an LS/LT platform is impossible due to the massive drainback windows around the headbolt locations. It won’t happen. The restriction holes will affect oil pressure very little in a hydraulic setup, because the metering is controlled at the rocker arm orifice. Solid roller setups however will bleed oil pressure (slightly) at the pushrod ends every time the lifter finds the base circle of the camshaft, because of lash.
its not like the whole lenght has the restriction, its only the tips. what are the sizes of the lifter orifices? if they are not substantially larger than 1.5mm (0.06") either its not worth further investigation.
btw, the holes in the rockers are 1.8mm stock and 1.1mm on the yellas.
Yep sacrifice oil to the top to save the bottom, when the top goes at any kind of rpm usually the bottom goes with it anyways.
I believe oil restriction to the top still provides an adequate oil supply to ensure reliability, but the main reason to restrict oil to the top end is it helps with windage control, and more high rpm power. If you're getting 40+ psi without restrictors, I'm sure youll get the same 40+psi with them. AFAIK, they're not for, and don't increase, low end oil supply, at least in an LS engine. The guy who owns Dart (can't think of his name) was quoted as saying the LS platform has over 15 gallons of oil/minute being pumped thru the engine at 6,500-7,000 rpm. He said that's WAY too much oil, and one reason (I'm sure it's not the only one) his LS blocks have priority main oiling. As for running them, go for it. I doubt the engine will know the difference. As I said, I ran them for years without any issue. But I also wonder if they were worth any power either.......
09-21-2022, 10:06 AM
