[SeventyNova]

Here is a picture of some pushrods I just pulled out of my 383, what are the potential causes of the damage to them? There are three damaged in the photo, two on the right one on the left.

It is a 383 with vortec heads, stock pushrods, comp pro magnum rockers, comp xs282 cam with matching springs. The heads have been machined for more lift at the spring and cleaned up a bit but thats it.

Unfortunatly there is some metal in the motor so I have to take it apart and see if anything is wrecked.

Any ideas of what I should change to avoid this next time?

thanks

Jon

 

[LTL EVIL]

Stock?

just ideas...but not trying to point out that there stock.
too tight
too loose
what did the lifters and rockers look like?
Mann sorry to hear. Good look on your next rebuild.
I'm sure someone with more expertesss...will chime in!

 

[batman09]

Valves not adjusted correctly?Did you use hardened pushrods?

 

[bowtie0069]

I had the same problem on my first engine--Comp roller tip rockers/stock pushrods. Had to get hardened pushrods to stop eating up the ends of them.

 

[SeventyNova]

Guess I'll get some hardened pushrods, pretty sure they were adjusted properly, the feeler gauge was tight at .016".

Would you guys take it all apart and replace bearings or just take the intake off and run a magnet through the lifter valley and insides of the heads and cross your fingers?

 

[racer77]

Hardend pushrods are the ticket, a must with solid cams. I've taken the chance with the magnet and changing the oil a couple quick times in a old race motor and it worked.Very minimal debris in the bearings when we tore it down 5 races later, but I think we were lucky. Your call........

 

[SeventyNova]

I cleaned out the lifter valley and heads and got quite a bit of junk out of it but not enough so I think its best to pull it apart and check and replace bearings. Better that than a bunch of machine work and new parts. I guess I know what I am doing for the next week or two in my spare time.

 

[stock z/28]

If it were me I would look at the depth and radius of the push rod seat in the rocker.

I have seen where it requires a push rod with a ball end to allow clearance and avoid binding.

Personally I prefer the style of push rod that you have put sometimes I have to use the ball end style.


this is just a guess guys but it may be worth looking at?



Good luck

Jeff

 

[bowtie0069]

On Steve Magnante's Wilshire Shaker, it has a complete Crane valvetrain that came in one big box--the pushrod seat in several of the rockers gets galled and some metal is transferred from the pushrods. He just cleans it up with a Dremel tool until it happens again. My Comps did the same sort of thing; when the pushrods got boogered up, it also left metal in the rockers. I did the Dremel tool thing a couple times, then threw out the cheesy roller tipped rockers and never had another problem.

 

[D-Man]

Those pushrods are too soft!! I've seen it at least a hundred times. You need to get some GOOD sticks in there.:yes:
http://www.pushrods.net/onepiece.html
Take a good hard look at the 5116 series. They come standard with the 210° clearance radius ends on one end for added rocker cup clearance:yes: and aren't that much different (price wise) than most everyone else's standard .080" wall stuff.:no:

 

[Paul Wright]

You never want to reuse stock pushrods in performance applications for two reasons.
1. They are very weak and flex under the higher loads of performance valvetrains.
2. The tips wear into the stock rockers and when you add a new rocker the minute differences lead to stress fractures.

Toss those stock wet noodles in the metal recycling bin and get a good set.

As far as cleaning the engine, that's a tough call. You may want to consider magnets to catch any stray pieces you may miss, but if one gets buy and into the pump you could have a seized pump and ensuing major problems.

 

[stock z/28]

How hard do think that push rod is, the one in the pic.?

How hard are the push rods you guys are suggesting?

 

[D-Man]

How hard do think that push rod is, the one in the pic.?

How hard are the push rods you guys are suggesting?

Ok.....I'll bite.

I'm not sure what GM used for material but I know the first step up would be a 1010 material that boasts 25% more column strength than OE. I'm not sure about the amount of heat treat they go through to get that though. Then of course is the 4140 and 4130 chrome moly materials that far surpass the 1010 and OE materials. The 4130 material has a tensile strength that ranges from 140,000 to 240,000 psi depending on the heat treatment it receives. Pushrods made of 4140 chrome moly can provide up to 275,000 psi of tensile strength with the right heat treatment.

But the more important question (in the original posters case) is in the hardness of the ends of the pushrod.....Especially the end riding against the rocker. They need to at least match the hardness of the pushrod cups of the Pro Magnum rockers or they will become a sacrificial piece....as seen in the photos.

What I recommended is a substantial upgrade not only because of the better ends of the pushrods but because he's running a solid lifter application as well.:yes:
As with fuel and ignition systems on nitrous cars, I'd rather suggest a little too much than just barely enough, or a "This will do" type part.
Pushrods are one of those parts you'd LIKE to install and forget about......Certainly not be the cause of another tear-down.

 

[stock z/28]

It wasnt a "trick" question.

I really dont know how hard a stock push rod is? Or an any other push rod.

I guess I could check a few.

My interest was basically that I never really associated a "hardness factor" to a push rod. I would be concerned that possibly a stock push rod may be too hard, and possibly brittle? I dont know.

I do know that I have used a lot of stock push rods over the years in engines that had lower spring rates (say 125lbs seat and 350 open) to around 7500 and had very little issues. In fact most of the time I would prefer a "selected" used stock push rod to a "budget" performance push rod.

If the rules allow it (and most do now) I always use a quality performance push rod.

I guess my concern is that when you see a damaged part (several in this case) I would like to have a good idea what the root cause of the failure was?

It may very be too soft of push rods? I certainly dont know, but if its in the design of the rocker arm, it may be another story.

I will hve to check the hardness on a few push rods. Im kinda curious what they are, and how much is case?

On kind of a side note, I have that almost all of the "stock" push rods from about the middle 70s are hard enough on the surface to work with a typical guide plate, in a typical application. I have seen some aftermarket "performance" push rods that would wear in the same application.
Sadly, I have encountered some "imported" guide plates that apparenty just mild steel and fail very quickly. In my opinion junk.

Thanks

Jeff

 

[D-Man]

Were the 70's pushrods work hardened?

I've seen a LOT of imported pushrods and guide plates in the last few years.:yes: PURE JUNK!!!uke:

There's been some rumors going around about some of the Comp rockers causing galling on the pushrods because of the hardness of their cups. Don't know for sure.

I've had a couple cheaper and not so cheap pushrods have the same problem as the original poster and replacing them with GOOD pieces fixed it every time. I caught mine when they were just starting to fracture so there wasn't any metal in the engine. I could literally use a pick and flake away the metal on the end because they were wore so thin.

Oil starvation or poor oil quality (low ZDDP content) could be to blame as well.:yes: I'd be interested to see if the pushrod tube or rocker orifice was clogged as well.:yes:

 

[Paul Wright]

I would say the issue is more about stiffness and tensile strength than hardness. Stock pushrods are too flexible and weak. They wind up being flexible pole vault poles... essentially springs.

The total spring rate and natural frequency of every component if the valvetrain system has an effect on stability and has to be considered. It has shown in Spintron testing that the pushrod can contribute to and have a significant effect on valve bounce.

Comp Cams recommends to replace the stock pushrods when using the Magnum rockers potential for failure:
Here's their troubleshooting page:
http://www.compcams.com/technical/Catalogs/106-07/381.pdf

When installing our Magnum Rocker Arms, be sure to
install new pushrods.
The old pushrods will show radius wear, making the old set incompatible
with the precision pushrod seat of the new rocker arms.

Just like lifters match camshaft lobes, pushrod tips wear to match the
pushrod seat in the rocker arm. Failure to change pushrods will result in
improper contact between the old pushrod and the new rocker arm, causing
damage to each

Q: Do I really need to replace my factory pushrods?

Pushrods play a critical role in transferring camshaft profiles to your intake and exhaust valves. Often overlooked during cam swaps and other engine upgrades, pushrods transfer lifter movement to the rocker while enduring pressures in excess of 1000 lbs per square inch.

In a high-rpm, high horsepower application, the demand on the pushrods is greatly increased. Factory pushrods are relatively weak compared to aftermarket pushrods, and physically can’t handle these added demands. The result is deflection or “bending” of the factory pushrods causing a loss in lift, duration, and ultimately -horsepower.

So whether you’re replacing your camshaft, upgrading rocker arms, or completely rebuilding your engine, it’s always a good idea to replace your OE pushrods with high quality, aftermarket units. COMP Cams® offers a variety of pushrod designs to suit nearly any application.

Note: Pushrods and rockers wear together much like a cam and lifters. Even though the pushrods may not show any wear, installing new rockers on old pushrods can result in premature failure because of microscopic stress fractures sustained by the pushrod from contact with an “unfamiliar” rocker surface.

Engine Builder mag tech article on pushrods and lifters

Tommorrows Technician article on Valvetrain technology

Circle Track article on Valve control Science

Interesting to note that flexible valve train ie; pushrods cause you to lose as much as 7 degrees of effective cam duration.

 

[stock z/28]

Please dont think that Im against replacing push rods as a good practice.

I guess what Im not conveying very well is the "style" of push rod had been an issue.

On some of the rockers (I wont mention brand) even if you used a new push rod that wasnt a "ball" type push rod, you would have the possibility of having the same issue.

 

[Paul Wright]

That's a good point Jeff. The ends need to mate with the sockets but how many people (other than us) actually check that?
for example: I imagine you could have a 5/16" ball end in a 3/8" socket or vice versa and that would be a bad thing.

 

[stock z/28]

Paul, in my opinion its not simply the size of the seat/push rod relationship its the depth and the degree of relife in the rocker socket itself.

Some of the rockers that I run accross require (in my opinion) a ball type push rod, or a push rod that is relieved around the tip, providing room for the rocker to pivot, with out binding on the side of the push rod.


I have several rockers here now that have this problem. If you used a staight push rod in them and had any sizable lift or geometry issue the pivot will bind.



The ball is just a "cheap fix" in my opinion.

I may be way wrong about this, but I much prefer a sraight push rod over the ball style and I simply wont use the with this type of rocker.


Jeff

 

[SeventyNova]

So what pushrod would you guys reccomend for my application?

I am thinking about something like this,

http://www.summitracing.com/parts/CCA-7970-16/

not sure on length or diameter which I will have to verify but is this a quality part or should I go with something else?