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Pump/Pushrod Ponderings...

beanhead

Straining The Limits Of Machine And Man
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I saw another thread going about our fuel pump pushrods, and naturally there's folks responding with their own bad experiences and even some pictures of worn-down ends, but it got me thinking....

It just doesn't take a ton of force to move that fuel pump arm. You can hold a pump in one hand, and operate the lever with the other. In addition there's oil (presumably) getting to the ends. So while it very well could be just inferior metals, for something that *shouldn't* be seeing a lot of pressure even at it's max stroke, they sure seem to be causing all kinds of hell...
Are there other possibilities worth considering? Is there anything else that could wear them down like that?

Pump arm manufactured at a funky angle, or other pump defect that that puts excess pressure on the pushrod, like the arm bottoming out?
Eccentric lobe finished too rough? Or not ground correctly, putting excess pressure on the pushrod?
Installing them without assembly grease causing a bad wear situation from start-up, like we've seen with lifters and other parts?
 
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Think if you did Melonite treatment to then they'd last, Cost to much for one part but a dozen or so?
melonite.JPG
 
Wasn't nothing wrong with the factory pushrods. Some are lasting well over 100k. Has to be the aftermarket Chinese, recycled junk!
 
Think if you did Melonite treatment to then they'd last, Cost to much for one part but a dozen or so?
View attachment 1171505
That or a surface nitride would have to help, you'd think?...But that assumes the pushrod manufacturing IS the problem (which it probably is...) I was just trying to look at it from a little different angle, to make sure we're treating the root cause and not just the symptom..
 
Wasn't nothing wrong with the factory pushrods. Some are lasting well over 100k. Has to be the afternarket Chinese, recycled junk!
Oh I'm sure....but are we still seeing that kind of longevity when used with aftermarket pumps and cams? You'd think all they'd have to do is make them out of the same stuff they make lifters out of, since they see considerably more punishment...(of course we know nothing's guaranteed with lifters anymore either!)
 
Oh I'm sure....but are we still seeing that kind of longevity when used with aftermarket pumps and cams? You'd think all they'd have to do is make them out of the same stuff they make lifters out of, since they see considerably more punishment...(of course we know nothing's guaranteed with lifters anymore either!)

Looking at the ones that wore prematurely, and they were mostly all aftermarket ones, you can see the outer "shell". Like they were heat treated on the outside but were made of a soft, regular/mild steel. I have one that did it. I didn't know it was in the condition it was in until I decided to pull the fuel pump for a over pressure problem. Now the fuel pump was found to have a very stiff spring and that was why it was putting out too much pressure. The spring being that strong was definitely a contributor to the push rod wearing but there has been some stock fuel pumps that had the push rod worn badly.

https://www.forbbodiesonly.com/moparforum/threads/mechanical-fuel-pump-101.194336/
 
Looking at the ones that wore prematurely, and they were mostly all aftermarket ones, you can see the outer "shell". Like they were heat treated on the outside but were made of a soft, regular/mild steel. I have one that did it. I didn't know it was in the condition it was in until I decided to pull the fuel pump for a over pressure problem. Now the fuel pump was found to have a very stiff spring and that was why it was putting out too much pressure. The spring being that strong was definitely a contributor to the push rod wearing but there has been some stock fuel pumps that had the push rod worn badly.
That's interesting about your pump issue..and yes I agree that little steel rod should still be able to do it's job and live to a ripe old age. Maybe they're making them to meet the "bare minimum" strength requirement and any increase in load does them in? Who knows....thanks for sharing.
 
Heat treating and surface hardening is a mainstay of several industries from firearms to aerospace. That said, if it was manufactured and treated in the USA, I am thinking the makers might have used the wrong alloy or just a surface treatment vs, heat treatment. With either, the core is softer so the part is not brittle. I did a quick search and the Chevy guys have the same issue.
 
Here is my last experience. Bought 3 "suposedly" nos rods. Bought from a guy who only sells old stuff, so I really have no reason to doubt him. This is with about 1200 miles of use.

20210724_082826.jpg 20210724_122158.jpg 20210724_122040.jpg
 
Heat treating and surface hardening is a mainstay of several industries from firearms to aerospace. That said, if it was manufactured and treated in the USA, I am thinking the makers might have used the wrong alloy or just a surface treatment vs, heat treatment. With either, the core is softer so the part is not brittle. I did a quick search and the Chevy guys have the same issue.
Thanks. That's another thing to think about...they might be designed and treated for "strength" but not necessarily for the grinding-type of wear they get subjected to.
 
I have never had a failure with one of these.
I'll also add that the arm on the Holley and Carter pumps I've used are NOT easy to press and move. I've had to press the lever against a table or wall and push the pump against it to get the arm to move.
 
The one installed in the 383 is an original oil pump rod and never had an issue with it. But my friends GTX 2 Comp Cams rods gone in a few months time. They were supposedly bronze tipped.
 
I read kryslerkid's other thread, yikes. I have an excellent lathe (Monarch 10ee) so making a pump rod is simple. It's the alloy and heat treat that's the issue. The bronze tip for a billet cam makes sense. Or could it be a combination of too much spring pressure and the wrong material(s). I see a return line and electric pump retro fit in my future
 
I think the obvious material is a 4140 alloy. ARP makes rods for Chevys. For Mopar it's import crap, Comp or Howards which looking at reviews at Summit, both brands have some failures.
 
I think the obvious material is a 4140 alloy. ARP makes rods for Chevys. For Mopar it's import crap, Comp or Howards which looking at reviews at Summit, both brands have some failures.
I can witness to the Comp ones not being worth the money or time to install....

Does this get down to what the cams are made of these days if even NOS rods are being eaten?
 
I have never had a failure with one of these.
I'll also add that the arm on the Holley and Carter pumps I've used are NOT easy to press and move. I've had to press the lever against a table or wall and push the pump against it to get the arm to move.
That's interesting too, I have a Carter "Street" pump I bought (probably from Mancini) back in the early 2000s, I remember working it by hand last year when I was swapping it on to my then-newly built engine. I could work it by hand without too much fuss but it was stiffer than the factory pump, so maybe they aren't making them like they used to?
 
I can witness to the Comp ones not being worth the money or time to install....

Does this get down to what the cams are made of these days if even NOS rods are being eaten?
Possibly...if not from the material then just the the not-so-good QC we've seen, maybe they're not paying as much attention and grinding the eccentric lobe put-of-spec.
 
Possibly...if not from the material then just the the not-so-good QC we've seen, maybe they're not paying as much attention and grinding the eccentric lobe put-of-spec.
It's quite disturbing to me (on this subject at least) that even NOS isn't a "safe haven"...
because there's plenty of anecdotal evidence that the originals lasted a very long time.
That tells me the cams aren't what they used to be and apparently are quite a bit more abrasive, for whatever
reason.
 
It's quite disturbing to me (on this subject at least) that even NOS isn't a "safe haven"...
because there's plenty of anecdotal evidence that the originals lasted a very long time.
That tells me the cams aren't what they used to be and apparently are quite a bit more abrasive, for whatever
reason.
Yes...since that pushrod end is riding on a lobe, like a lifter does, it could be ground into oblivion if that eccentric lobe wasn't finished properly....I'd say the odds aren't terrible that that's the cause of at least some of the failures.
 
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