Hardened Pushrods - what are the advantages?
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Teching In
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From: Canada
Hardened Pushrods - what are the advantages? I'm about to order a cam for my car. I'm leaning towards the TR 224/224 114 LSA. This car is a daily driver and must pass emissions. Now I am planning on buying the cam and the springs.
But for another $200 I can get titanium retainers as well as hardened pushrods. I see the value of the retainers but don't see why I would want the pushrods.
From what I understand if I mis-shifted my car (which I have done in the past and bent my pushrods) and I have hardened pushrods, wouldn't they break something else in the car by not bending??
Can you tell me why I would want to spend the extra money on the pushrods?
Thanks in advance.
But for another $200 I can get titanium retainers as well as hardened pushrods. I see the value of the retainers but don't see why I would want the pushrods.
From what I understand if I mis-shifted my car (which I have done in the past and bent my pushrods) and I have hardened pushrods, wouldn't they break something else in the car by not bending??
Can you tell me why I would want to spend the extra money on the pushrods?
Thanks in advance.
For the bee hive style spring such as a comp 918, there is only 2 grams difference in weight between a Ti retainer and stock because the retainer is so small. 9 grams vs 11 grams. I'm not suggesting not to get them. Just throwing out some info. I found no difference in weight between stock push rods and Thunder Racing Ch/Mol push rods. Their advantage would be in less deflection at higher rpms with stiffer springs. All parts were weighed on a tripple beam scale.
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Thread Starter
Teching In
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From: Canada
Well, I'm hoping not to miss any more shifts since I cut some length off my B&M but you never know what may happen!
So what WOULD happen if I had hardened pushrods and misshifted down a gear at redline??
So what WOULD happen if I had hardened pushrods and misshifted down a gear at redline??
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Originally Posted by BillSS
Well, I'm hoping not to miss any more shifts since I cut some length off my B&M but you never know what may happen!
So what WOULD happen if I had hardened pushrods and misshifted down a gear at redline??
So what WOULD happen if I had hardened pushrods and misshifted down a gear at redline??
Oh no, not this debate again 
. The pushrod was never designed to be a fusible link in the valvetrain. Several years ago we even had a member (might have been in the old LS1.com days) that was an engineer from Jesel (don't recall his ID) and he was adamantly opposed to the notion that the LS1 pushrods were designed to break in the event of a mechanical over-rev. The job of the pushrod is to accurately transmit the motion of the cam lobe (via the rocker arm) to the valve. If its flexing under load, then its simply not doing its job.
Look at it this way, you CAN mechanically over-rev any engine - pushrod, OHC, rotary, or otherwise - and cause damage. There is nothing unique or special about the LS1 pushrods making them fusible.
This is like saying that you broke your ring gear on a missed shift so therefore everybody should continue using the weak 10-bolt rearends. Just a silly, backwards argument IMO - especially when you're considered an aggressive cam with heavier valvesprings...
. The pushrod was never designed to be a fusible link in the valvetrain. Several years ago we even had a member (might have been in the old LS1.com days) that was an engineer from Jesel (don't recall his ID) and he was adamantly opposed to the notion that the LS1 pushrods were designed to break in the event of a mechanical over-rev. The job of the pushrod is to accurately transmit the motion of the cam lobe (via the rocker arm) to the valve. If its flexing under load, then its simply not doing its job. Look at it this way, you CAN mechanically over-rev any engine - pushrod, OHC, rotary, or otherwise - and cause damage. There is nothing unique or special about the LS1 pushrods making them fusible.
This is like saying that you broke your ring gear on a missed shift so therefore everybody should continue using the weak 10-bolt rearends. Just a silly, backwards argument IMO - especially when you're considered an aggressive cam with heavier valvesprings...
Thread Starter
Teching In
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From: Canada
Good point but I guess my predicament is that is my 224 cam really that aggressive?
Enough to justify hardened pushrods and retainers??
Assuming that money plays a bit of a factor here is it worth the extra dollars considering this specific cam?
Enough to justify hardened pushrods and retainers??
Assuming that money plays a bit of a factor here is it worth the extra dollars considering this specific cam?
With stock cam and valvetrain, I would say yes stick with stock pushrods...but going with a bigger cam go with the hardened ones. You dont want to have a planned weak link in your car. IMO it would defeat the whole point of getting a stronger valvetrain. The extra strength of the valvetrain would never be used if your pushrods cant even handle it.
Originally Posted by Fulton 1
Oh no, not this debate again . The pushrod was never designed to be a fusible link in the valvetrain. Several years ago we even had a member (might have been in the old LS1.com days) that was an engineer from Jesel (don't recall his ID) and he was adamantly opposed to the notion that the LS1 pushrods were designed to break in the event of a mechanical over-rev. The job of the pushrod is to accurately transmit the motion of the cam lobe (via the rocker arm) to the valve. If its flexing under load, then its simply not doing its job.
Look at it this way, you CAN mechanically over-rev any engine - pushrod, OHC, rotary, or otherwise - and cause damage. There is nothing unique or special about the LS1 pushrods making them fusible.
This is like saying that you broke your ring gear on a missed shift so therefore everybody should continue using the weak 10-bolt rearends. Just a silly, backwards argument IMO - especially when you're considered an aggressive cam with heavier valvesprings...
. The pushrod was never designed to be a fusible link in the valvetrain. Several years ago we even had a member (might have been in the old LS1.com days) that was an engineer from Jesel (don't recall his ID) and he was adamantly opposed to the notion that the LS1 pushrods were designed to break in the event of a mechanical over-rev. The job of the pushrod is to accurately transmit the motion of the cam lobe (via the rocker arm) to the valve. If its flexing under load, then its simply not doing its job. Look at it this way, you CAN mechanically over-rev any engine - pushrod, OHC, rotary, or otherwise - and cause damage. There is nothing unique or special about the LS1 pushrods making them fusible.
This is like saying that you broke your ring gear on a missed shift so therefore everybody should continue using the weak 10-bolt rearends. Just a silly, backwards argument IMO - especially when you're considered an aggressive cam with heavier valvesprings...
Valve train stability is what everyone should be after. Lighter parts and parts that flex less provide more stability.
BTW, the term "hardened pushrod" used to mean nothing more than a pushrod that was surface hardened to allow it to rub and not wear against pushrod guide plates. I now see the term being thrown around as something stiffer or stronger. Misconception?? or am I missing something??
I run stock pushrods in my motor. Sees 7k all the time and has seen 7500 a few times. I've checked them. They are fine 
If it ain't broke, I'm not gonna fix it. They seem to be strong enough for there to be no need for the hardened ones.
If it ain't broke, I'm not gonna fix it. They seem to be strong enough for there to be no need for the hardened ones.
Originally Posted by 4mulaJoe
I run stock pushrods in my motor. Sees 7k all the time and has seen 7500 a few times. I've checked them. They are fine If it ain't broke, I'm not gonna fix it. They seem to be strong enough for there to be no need for the hardened ones.
If it ain't broke, I'm not gonna fix it. They seem to be strong enough for there to be no need for the hardened ones.
TECH Apprentice
Joined: Oct 2003
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From: miami, florida
look, i just put the same cam you want except mine is on a 112 lsa. i got the hardened pushrods and comp cam springs with titatnium retainers and let me tell you that the insurance you have with all these items is awesome. i had two bent pushrods without me even knowing and since you are already there why put the same stock items on again? i suggest you get everything in one shot and get it done right. i did the cam myself and it is very easy if you have tools. the car will be noisier, but thats just how it is. you will love the cam you are gonna get and i am on stock tuning on my 99 camaro ss. do the job right one time so you have to go back again and replace springs and pushrods later on. get the whole package and be confident that your internals will be ok.
We need some Mechanical Engineers to jump in on this pushrod flex issue. Here's my .02.
What is being discussed is a material property called "Modulus of Elasticity". Most steels all have nearly the same value. (Brass and Aluminum are different materials and have radically different Modulus'). Heat treating the steel makes it stronger, but it can't change the "Modulus". Stronger doesn't me the ability to resist deflection, it means the ability to absorb stress and not "Yield" or break. If the two different style pushrods have the same circular dimensions, that is, the same OD and same ID then the flex under the same load will be identical between the stock and the hardened pushrod. The difference is that the hardened pushrod has a higher "Yield" strength which allows it to take more stress than the stock pushrod and still return to it's original unloaded state. It will still flex, it just won't stay that way as easily. The only way to reduce the flex is to increase the pushrod's material cross-section. This is most easily done by increasing the rod's outside diameter; like from 5/16 to 3/8.
The same thing happens on stud mounted rockers. Going from a heat-treated 3/8 stud to a heat-treated 7/16 stud reduces rocker deflection because the stud's cross sectional area has increased by 36%. The heat-treatment just keeps them from staying bent or breaking so easily.
Now that was a mouthful!
How about some of you ME student/graduates jumping in here and tell me I'm full of it?
John
What is being discussed is a material property called "Modulus of Elasticity". Most steels all have nearly the same value. (Brass and Aluminum are different materials and have radically different Modulus'). Heat treating the steel makes it stronger, but it can't change the "Modulus". Stronger doesn't me the ability to resist deflection, it means the ability to absorb stress and not "Yield" or break. If the two different style pushrods have the same circular dimensions, that is, the same OD and same ID then the flex under the same load will be identical between the stock and the hardened pushrod. The difference is that the hardened pushrod has a higher "Yield" strength which allows it to take more stress than the stock pushrod and still return to it's original unloaded state. It will still flex, it just won't stay that way as easily. The only way to reduce the flex is to increase the pushrod's material cross-section. This is most easily done by increasing the rod's outside diameter; like from 5/16 to 3/8.
The same thing happens on stud mounted rockers. Going from a heat-treated 3/8 stud to a heat-treated 7/16 stud reduces rocker deflection because the stud's cross sectional area has increased by 36%. The heat-treatment just keeps them from staying bent or breaking so easily.
Now that was a mouthful!
How about some of you ME student/graduates jumping in here and tell me I'm full of it?
John