Debate: Hardened pushrods vs. stock pushrods
09-03-2002, 05:58 PM
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Debate: Hardened pushrods vs. stock pushrods I've heard arguments for and against both.
The stock pushrods are weak, bend easy, and you can conceivably lose a few ponies by using a non-hardened pushrods. However, better to bend a pushrod then break a valve.
The hardened pushrods are much stronger, better transfer of energy/power, don't bend, but, turn the valves or other parts of your heads into the weak link, which is more costly to fix.
I have your typical Ferrea valves, and Comp 987 double springs. My question is which pushrods are best for me??
I do rev the car to 6800 at times....
The stock pushrods are weak, bend easy, and you can conceivably lose a few ponies by using a non-hardened pushrods. However, better to bend a pushrod then break a valve.
The hardened pushrods are much stronger, better transfer of energy/power, don't bend, but, turn the valves or other parts of your heads into the weak link, which is more costly to fix.
I have your typical Ferrea valves, and Comp 987 double springs. My question is which pushrods are best for me??
I do rev the car to 6800 at times....
09-03-2002, 06:09 PM
#2
Re: Debate: Hardened pushrods vs. stock pushrods IMHO, if your car is just for 'spirited' driving, and the occasional trip down to the strip, I wouldn't bother with hardened pushrods. Pulling the heads and revalving is a real PITA. Misshifts happen more often than people tend to think.
If you are road racing or a weekly warrior to the track then go for the hardened pushords. Odds are that you are breaking **** often enough anyways. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
If you are road racing or a weekly warrior to the track then go for the hardened pushords. Odds are that you are breaking **** often enough anyways. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
09-05-2002, 01:06 PM
#4
Re: Debate: Hardened pushrods vs. stock pushrods I would think that with the combination of the aggressive cam lobes, the increased spring pressure, and revving the car another 600rpm over the stock limiter, it would be in the best interest to put hardened pushrods. You're not going to bend the valves from just revving to 6800rpm... but there is a pretty good chance of bending a stock pushrod at 6800rpm with those cam ramps and springs.
Stock valvetrain, stay with stock pushrods.
Aftermarket valvetrain, go with the good stuff.
Besides, I'm pretty sure there's a reason cam packages come with hardened pushrods... other than to just sell a 120 dollar item.
Stock valvetrain, stay with stock pushrods.
Aftermarket valvetrain, go with the good stuff.
Besides, I'm pretty sure there's a reason cam packages come with hardened pushrods... other than to just sell a 120 dollar item.
09-05-2002, 03:05 PM
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Re: Debate: Hardened pushrods vs. stock pushrods </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by xaon:
<strong>I would think that with the combination of the aggressive cam lobes, the increased spring pressure, and revving the car another 600rpm over the stock limiter, it would be in the best interest to put hardened pushrods. You're not going to bend the valves from just revving to 6800rpm... but there is a pretty good chance of bending a stock pushrod at 6800rpm with those cam ramps and springs.
Stock valvetrain, stay with stock pushrods.
Aftermarket valvetrain, go with the good stuff.
Besides, I'm pretty sure there's a reason cam packages come with hardened pushrods... other than to just sell a 120 dollar item.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Thats kind of what I was thinking...I have an agressive cam that revs to 6800rpm frequently...
I'm just afraid to damage something other than a pushrod in the event of a missed shift.
<strong>I would think that with the combination of the aggressive cam lobes, the increased spring pressure, and revving the car another 600rpm over the stock limiter, it would be in the best interest to put hardened pushrods. You're not going to bend the valves from just revving to 6800rpm... but there is a pretty good chance of bending a stock pushrod at 6800rpm with those cam ramps and springs.
Stock valvetrain, stay with stock pushrods.
Aftermarket valvetrain, go with the good stuff.
Besides, I'm pretty sure there's a reason cam packages come with hardened pushrods... other than to just sell a 120 dollar item.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Thats kind of what I was thinking...I have an agressive cam that revs to 6800rpm frequently...
I'm just afraid to damage something other than a pushrod in the event of a missed shift.
09-05-2002, 03:52 PM
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Re: Debate: Hardened pushrods vs. stock pushrods Heavy springs, good lifters, and a good timing chain are the answer if you want to be 100% confident that a missed shift won't tear anything up.
It is my opinion that the reason that missed shifts/mis-shifts notoriously tweak factory push rods is because the stock valve springs are not Scottish (and, as we all know, if it's not Scottish, IT'S CRAP!!). As such, a mechanical over-rev (such as the case with the infamous 3-to-2 shift) results in valve float, which in turn shocks the hell out of the valve train. The pushrods are simply the weakest link.
According to my theory, it goes like this:
- engine mechanically over-revved, resulting in the cam spinning faster than it would under even severe driving (like a drag race)
- stock valve springs do not have enough pressure to keep the roller lifter in contact with the cam lobe, and the result is that the lifter "jumps" (or is "thrown" over) the back side of the lobe
- the valve spring now only has to push the weight of the valve train (rocker, pushrod, and lifter), and the lifter eventually "lands" on the cam; a SEVERE shock to the valve train is the result
- since the lifter is hydraulic and can only bleed off oil so fast, it can not absorb all of the shock; however, the valve train still has inertia going for it.
- the weakest link (pushrods) simply gives way
By looking at this, we can see why replacing stock pushrods with hardened pushrods while staying with stock springs is a bad idea- because instead of the pushrod giving way and allowing the valve to close, the pushrod holds and the valve stays open. All sorts of ugliness can ensue. We can also see why lightening the valve train is a good idea- because the lighter it is, the quicker it can change directions.
Most serious engine builders will tell you that it's better to run too much valve spring pressure than not enough. The issue that we have to face (unless we're talking a solid roller setup) is that high valve spring pressures on stock lifters cause the lifter to collapse. The result is slack in the valvetrain; along with that comes loss of performace (the lifter is absorbing some of the duration and lift that the cam is providing), and yet more shock loads to the valvetrain.
Myself, I'm not touching the cam until:
a) the valve spring situation is sorted out
b) I can afford some prepped hydraulic roller liftes (perhaps Schubeck-modified Cranes, or similar)
c) I can afford a high quality timing chain
d) I can afford a good set of rockers where I won't have to worry about the needle bearings letting loose
I know that plenty of folks out there get by without doing all of that stuff, and it works just fine for them. It's just that I hate to end up with a mess of busted parts 'cause I was a cheap *** and didn't do it "right" the first time.
Just my $.02...
It is my opinion that the reason that missed shifts/mis-shifts notoriously tweak factory push rods is because the stock valve springs are not Scottish (and, as we all know, if it's not Scottish, IT'S CRAP!!). As such, a mechanical over-rev (such as the case with the infamous 3-to-2 shift) results in valve float, which in turn shocks the hell out of the valve train. The pushrods are simply the weakest link.
According to my theory, it goes like this:
- engine mechanically over-revved, resulting in the cam spinning faster than it would under even severe driving (like a drag race)
- stock valve springs do not have enough pressure to keep the roller lifter in contact with the cam lobe, and the result is that the lifter "jumps" (or is "thrown" over) the back side of the lobe
- the valve spring now only has to push the weight of the valve train (rocker, pushrod, and lifter), and the lifter eventually "lands" on the cam; a SEVERE shock to the valve train is the result
- since the lifter is hydraulic and can only bleed off oil so fast, it can not absorb all of the shock; however, the valve train still has inertia going for it.
- the weakest link (pushrods) simply gives way
By looking at this, we can see why replacing stock pushrods with hardened pushrods while staying with stock springs is a bad idea- because instead of the pushrod giving way and allowing the valve to close, the pushrod holds and the valve stays open. All sorts of ugliness can ensue. We can also see why lightening the valve train is a good idea- because the lighter it is, the quicker it can change directions.
Most serious engine builders will tell you that it's better to run too much valve spring pressure than not enough. The issue that we have to face (unless we're talking a solid roller setup) is that high valve spring pressures on stock lifters cause the lifter to collapse. The result is slack in the valvetrain; along with that comes loss of performace (the lifter is absorbing some of the duration and lift that the cam is providing), and yet more shock loads to the valvetrain.
Myself, I'm not touching the cam until:
a) the valve spring situation is sorted out
b) I can afford some prepped hydraulic roller liftes (perhaps Schubeck-modified Cranes, or similar)
c) I can afford a high quality timing chain
d) I can afford a good set of rockers where I won't have to worry about the needle bearings letting loose
I know that plenty of folks out there get by without doing all of that stuff, and it works just fine for them. It's just that I hate to end up with a mess of busted parts 'cause I was a cheap *** and didn't do it "right" the first time.
Just my $.02...
09-05-2002, 03:52 PM
#7
Re: Debate: Hardened pushrods vs. stock pushrods I would really be afraid to rev the car to 6500-6600RPM ,like I do now, without the hardened pushrods in there. With good springs good pushrods there is very little chance of the valves kissing the pistons.
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09-05-2002, 04:40 PM
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Re: Debate: Hardened pushrods vs. stock pushrods </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by BurnOut:
<strong>Heavy springs, good lifters, and a good timing chain are the answer if you want to be 100% confident that a missed shift won't tear anything up.
</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Part of what you are saying is why I went with Comp 987 double springs, titanium retainers, and a JWIS timing chain, hoping to reduce damage done from things like missed shifts.
I have a feeling I'll be going through stock pushrods like water, but that may be a risk I'll take if it means that I won't be damaging valves.
<strong>Heavy springs, good lifters, and a good timing chain are the answer if you want to be 100% confident that a missed shift won't tear anything up.
</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Part of what you are saying is why I went with Comp 987 double springs, titanium retainers, and a JWIS timing chain, hoping to reduce damage done from things like missed shifts.
I have a feeling I'll be going through stock pushrods like water, but that may be a risk I'll take if it means that I won't be damaging valves.
09-06-2002, 05:18 AM
#10
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Re: Debate: Hardened pushrods vs. stock pushrods with a M6 im from the
stock push rods are like fuses they will bend
for $12 bucks each where otherwise you can
bend up something way more expensive. I dont
belive your loosing horsepower there.
stock push rods are like fuses they will bend
for $12 bucks each where otherwise you can
bend up something way more expensive. I dont
belive your loosing horsepower there.
09-06-2002, 10:01 AM
#11
Re: Debate: Hardened pushrods vs. stock pushrods </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by verbs:
<strong> </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by BurnOut:
<strong>Heavy springs, good lifters, and a good timing chain are the answer if you want to be 100% confident that a missed shift won't tear anything up.
</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Part of what you are saying is why I went with Comp 987 double springs, titanium retainers, and a JWIS timing chain, hoping to reduce damage done from things like missed shifts.
I have a feeling I'll be going through stock pushrods like water, but that may be a risk I'll take if it means that I won't be damaging valves.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">The stock pushrods DON'T SUCK, and WILL be able to take any kind of abuse your setup intends to give them. As long as you are not floating the springs in the upper RPM, you don't have anything to worry about.
A lot of high HP cars are still using the stock PR.
<strong> </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by BurnOut:
<strong>Heavy springs, good lifters, and a good timing chain are the answer if you want to be 100% confident that a missed shift won't tear anything up.
</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Part of what you are saying is why I went with Comp 987 double springs, titanium retainers, and a JWIS timing chain, hoping to reduce damage done from things like missed shifts.
I have a feeling I'll be going through stock pushrods like water, but that may be a risk I'll take if it means that I won't be damaging valves.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">The stock pushrods DON'T SUCK, and WILL be able to take any kind of abuse your setup intends to give them. As long as you are not floating the springs in the upper RPM, you don't have anything to worry about.
A lot of high HP cars are still using the stock PR.
09-06-2002, 10:21 AM
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Re: Debate: Hardened pushrods vs. stock pushrods The only question that I have regarding the factory pushrods in a modified motor is if they can take the additional pressure from the stronger valve springs.
SStolen- what the timing chain does is synchronize the position of the cam with the position of the crank. In other words, it ensures that the timing of the valve events in relation to piston location is consistent.
As far as what makes one timing chain better than another, the battle that has to be fought with timing chains is stretch. Stretch cane be reduced by going to a thicker chain (double row), using superior materials, adding rollers to the chain (so that it "rolls" on to and off of the timing gears instead of being slid off); or any combination thereof.
SStolen- what the timing chain does is synchronize the position of the cam with the position of the crank. In other words, it ensures that the timing of the valve events in relation to piston location is consistent.
As far as what makes one timing chain better than another, the battle that has to be fought with timing chains is stretch. Stretch cane be reduced by going to a thicker chain (double row), using superior materials, adding rollers to the chain (so that it "rolls" on to and off of the timing gears instead of being slid off); or any combination thereof.
09-06-2002, 10:41 AM
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Re: Debate: Hardened pushrods vs. stock pushrods 40k miles on stock pushrods with hotcam/springs.
no valve float, no bent pushrods.
12.5@114 w/ 2.0 60ft @ 3500lb's
stock gears & ls1 intake @ 1800ft DA.
no valve float, no bent pushrods.
12.5@114 w/ 2.0 60ft @ 3500lb's
stock gears & ls1 intake @ 1800ft DA.
09-06-2002, 10:51 AM
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Re: Debate: Hardened pushrods vs. stock pushrods I don't think there is a debate at all over this topic; agressive cams put alot more stress on the valvetrain, and hardened pushrods are just one more measure to keep everything in order.
Besides, it seems like you are concerned about eeking every last bit of power from your setup so hardened pushrods would be an easy mod to do.
Besides, it seems like you are concerned about eeking every last bit of power from your setup so hardened pushrods would be an easy mod to do.
09-06-2002, 04:00 PM
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Re: Debate: Hardened pushrods vs. stock pushrods It has been said that stock pushrods are only good up to 7000 RPMs so if you spin it to that then you should probably get new push rods. Its a simple mod and will be the best in the long run. Sure you can hit high RPMs a few times with the stock ones but after awhile they will bend and you will have to replace them anyways. Why not replace them now and only once instead of later and probably a few times.
09-07-2002, 12:45 AM
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Re: Debate: Hardened pushrods vs. stock pushrods </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Fenris Ulf:
<strong>I don't think there is a debate at all over this topic; agressive cams put alot more stress on the valvetrain, and hardened pushrods are just one more measure to keep everything in order.
Besides, it seems like you are concerned about eeking every last bit of power from your setup so hardened pushrods would be an easy mod to do.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">You pretty much have it right Fenris....I want to get the hardened pushrods...for their durability possible minor power gains and whatnot, but don't want them at the expense of my valves or any other part of my engine.
I'm hoping I don't get valve float with my upgraded valvetrain, but I do have stronger springs and I do spin my car to 7000rpms at times, and am wondering if the stock pushrods are up to the task.
If not it's hardened pushrod time for me.
<strong>I don't think there is a debate at all over this topic; agressive cams put alot more stress on the valvetrain, and hardened pushrods are just one more measure to keep everything in order.
Besides, it seems like you are concerned about eeking every last bit of power from your setup so hardened pushrods would be an easy mod to do.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">You pretty much have it right Fenris....I want to get the hardened pushrods...for their durability possible minor power gains and whatnot, but don't want them at the expense of my valves or any other part of my engine.
I'm hoping I don't get valve float with my upgraded valvetrain, but I do have stronger springs and I do spin my car to 7000rpms at times, and am wondering if the stock pushrods are up to the task.
If not it's hardened pushrod time for me.
