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I replaced the stock valve springs at 63,688 miles because I race the car and it spends some time at the redline. The new springs are GM Performance springs 19420455, which are the current equivalent to the original springs.
The new springs had an uninstalled height of 2.120 inches. The springs I took out were (4) at 2.110", (7) at 2.100", (1) at 2.095", (1) at 2.090", (2) at 2.085", (1) at 2.075". Rounded to the nearest .005"
None of the old springs were as tall as the new springs so all the springs had suffered some fatigue. I do not have a way to measure the spring pressure. The engine is stock.
Great findings. Just curious if you saw any valve float on a dyno, or just doing some good preventative maintenance on a 20 yr old car?
PM. I have had valve spring failure on 454 engines before and it was not pleasant.
Originally Posted by captain vette
Are these new springs expensive, I’ve a 03 with around 55k all stock engine
The springs are not expensive, but you also need the valve spring compressor, the adapter to attach to your air compressor to keep the valves in place. About $200 all totaled. But you have to remove the coils, spark plugs and valve covers. So I replaced the plugs, wires and gaskets. I also found unbolting and moving aside the alternator made things much easier so I replace the serpentine belt. I changed most wear items that I had to touch. Later I will total my receipts and post the amount spent.
I replaced the stock valve springs at 63,688 miles because I race the car and it spends some time at the redline. The new springs are GM Performance springs 19420455, which are the current equivalent to the original springs.
The new springs had an uninstalled height of 2.120 inches. The springs I took out were (4) at 2.110", (7) at 2.100", (1) at 2.095", (1) at 2.090", (2) at 2.085", (1) at 2.075". Rounded to the nearest .005"
None of the old springs were as tall as the new springs so all the springs had suffered some fatigue. I do not have a way to measure the spring pressure. The engine is stock.
Pretty sure the springs have always been those heights.
A fatigue failure is due to a large number of cycles at a specific load. Springs to not sag unless they are deflected beyond their yield point.
I replaced the stock valve springs at 63,688 miles because I race the car and it spends some time at the redline. The new springs are GM Performance springs 19420455, which are the current equivalent to the original springs.
The new springs had an uninstalled height of 2.120 inches. The springs I took out were (4) at 2.110", (7) at 2.100", (1) at 2.095", (1) at 2.090", (2) at 2.085", (1) at 2.075". Rounded to the nearest .005"
None of the old springs were as tall as the new springs so all the springs had suffered some fatigue. I do not have a way to measure the spring pressure. The engine is stock.
All springs, be they suspension springs, valve springs, or the spring in your ball point pen are going to loose a bit of uninstalled height after being in service for any meaningful amount of time. Yes, they will "take a set" but, they will more, or less stay there, unless forced to function beyond their design limits, or exposed to excessive heat. I wouldn't necessarily consider this to be "fatigue," unless they are unable to produce the necessary seat pressure at, or near the specified installed height. Your measurements are quite interesting, but they really do not reveal the true capabilities of the old springs. You really need access to a spring tester to make an informed judgement about the serviceability of those springs.
All springs, be they suspension springs, valve springs, or the spring in your ball point pen are going to loose a bit of uninstalled height after being in service for any meaningful amount of time. Yes, they will "take a set" but, they will more, or less stay there, unless forced to function beyond their design limits, or exposed to excessive heat. I wouldn't necessarily consider this to be "fatigue," unless they are unable to produce the necessary seat pressure at, or near the specified installed height. Your measurements are quite interesting, but they really do not reveal the true capabilities of the old springs. You really need access to a spring tester to make an informed judgement about the serviceability of those springs.
Spring testers are too expensive to buy just for fun. I will ask around to see if someone nearby has access to one.
This is something I always suggest when folks mod the cars. Particularly when adding a supercharger or boost application which applies even more force to the valves. So to prevent the chance of premature loss of the curve or fluctuating lines at peak rpm due to valve float, always replace or upgrade the valve springs. Especially now that these cars are in some cases up to 27 years old.
This is something I always suggest when folks mod the cars. Particularly when adding a supercharger or boost application which applies even more force to the valves. So to prevent the chance of premature loss of the curve or fluctuating lines at peak rpm due to valve float, always replace or upgrade the valve springs. Especially now that these cars are in some cases up to 27 years old.
I wholeheartedly agree that the springs should be replaced, particularly in light of the history on the Gen III. This is doubly important if you are going to increase power output and/or you intend to beat on the car. But, I would suggest that caution be exercised if upgrading springs, as the OE lifters and pushrods were neither intended, nor designed to deal with excessive over the nose valve spring pressures. Your upgrade could very easily cause more problems than it solves!
Choose wisely, or consider upgrading the balance of the valvetrain components at the same time. If going this route, it is essential that the lifter trays be replaced with genuine GM parts for best engine reliability.
Pretty sure the springs have always been those heights.
A fatigue failure is due to a large number of cycles at a specific load. Springs to not sag unless they are deflected beyond their yield point.
I agree. When installed at the standard 1.8" they just have some minor differences in seat pressure.
This is something I always suggest when folks mod the cars. Particularly when adding a supercharger or boost application which applies even more force to the valves. So to prevent the chance of premature loss of the curve or fluctuating lines at peak rpm due to valve float, always replace or upgrade the valve springs. Especially now that these cars are in some cases up to 27 years old.
Something like these fluctuating lines at or above 5800 rpm or so?
HP line goes wonky above 5800. Torque has the big missing funky spot as well at about the same rpm.
I can't help but wonder if this was due to the valves bouncing due to lack of spring pressure on my TSP .550 "low lift" cam.
Good conversation about springs. I'm edumicating myself. I may have some lightly used LS6 springs for sale...
Something like these fluctuating lines at or above 5800 rpm or so?
HP line goes wonky above 5800. Torque has the big missing funky spot as well at about the same rpm.
I can't help but wonder if this was due to the valves bouncing due to lack of spring pressure on my TSP .550 "low lift" cam.
Good conversation about springs. I'm edumicating myself. I may have some lightly used LS6 springs for sale...
Springs that are too strong can also cause the valves to bounce. How is this possible? When opening the valve, an excessively stiff spring can cause the pushrod to flex like a spring, storing energy. As the valve closes, the pushrod straightens out, releasing the stored energy. This sudden release can make the valve bounce off of the seat. Obviously, weak springs can allow the same problem, particularly if the ramps on the cam lobes are on the aggressive side.
Installing random parts can lead to problems, therefore, all of the valvetrain components need to be well coordinated, so that they work well together. You should always use the cam grinder's valvetrain recommendations, unless you truly have the knowledge to deviate from same. When in doubt, always consult with your cam grinder, or an experienced engine builder for guidance.
Springs that are too strong can also cause the valves to bounce. How is this possible? When opening the valve, an excessively stiff spring can cause the pushrod to flex like a spring, storing energy. As the valve closes, the pushrod straightens out, releasing the stored energy. This sudden release can make the valve bounce off of the seat. Obviously, weak springs can allow the same problem, particularly if the ramps on the cam lobes are on the aggressive side.
Installing random parts can lead to problems, therefore, all of the valvetrain components need to be well coordinated, so that they work well together. You should always use the cam grinder's valvetrain recommendations, unless you truly have the knowledge to deviate from same. When in doubt, always consult with your cam grinder, or an experienced engine builder for guidance.
These are the springs that came with the cam kit, supplied by the cam grinder, TSP. I'll call TSP at some point and ask what they think about the depicted graph. I did send it to the salesman post dyno run, however I did not ask about the blips on the upper rpm range. I think for what the cam is it is on the upper end of power, just wondering if there is possibly a better spring. I was thinking PAC1218X for longevity as well as a touch more spring pressure. I'll check the work of TSP as far as installed height while I'm there. Depending on what the tech people at TSP tell me about the LS6 springs. They may supply the LS6 spring as a way to reduce cost? My plan is to ask TSP tech folks at this point.
Here is the cam (as a kit with springs) I bought btw https://www.texas-speed.com/p-9501-t...-camshaft.aspx
Something like these fluctuating lines at or above 5800 rpm or so?
HP line goes wonky above 5800. Torque has the big missing funky spot as well at about the same rpm.
I can't help but wonder if this was due to the valves bouncing due to lack of spring pressure on my TSP .550 "low lift" cam.
Good conversation about springs. I'm edumicating myself. I may have some lightly used LS6 springs for sale...
Thats just dyno noise. I wouldnt worry about it. My stock engine does the same thing.
That graph looks nice and smooth, I wouldn't suspect any valve float. I'd also doubt highly a stiffer spring will do much of anything for you, given that your are already running the recommended springs. TSP is not shy about recommending their brand of dual springs, so that should tell you something. LS6 springs are typically only recommended when the cam uses softer lobes, and it looks like this cam is easy on the valvetrain.
These are the springs that came with the cam kit, supplied by the cam grinder, TSP. I'll call TSP at some point and ask what they think about the depicted graph. I did send it to the salesman post dyno run, however I did not ask about the blips on the upper rpm range. I think for what the cam is it is on the upper end of power, just wondering if there is possibly a better spring. I was thinking PAC1218X for longevity as well as a touch more spring pressure. I'll check the work of TSP as far as installed height while I'm there. Depending on what the tech people at TSP tell me about the LS6 springs. They may supply the LS6 spring as a way to reduce cost? My plan is to ask TSP tech folks at this point.
Here is the cam (as a kit with springs) I bought btw https://www.texas-speed.com/p-9501-t...-camshaft.aspx
In a competitive market, TSP would certainly want to target a specific price point. Their description of this cam kit makes that clear. I suppose their design allows for comparatively gentle ramps on the lobes, due to the low lift, eh? That said, they may be more concerned about including higher pressure springs in a kit which is intended to use OE Gen III lifters. It doesn't take much spring seat pressure to collapse the LS1 / LS6 lifters plus these lifters are mechanically fragile, which is why everyone and their brother recommends an upgrade to LS7 lifters at the very least.
It seems to me that the OE LS6 valve springs are just adequate enough for the OE LS6 camshaft and any other "performance" cam that they could safely be paired with wouldn't be much of an upgrade over the OE LS6 cam. Again, that's why it was necessary for TSP to limit the lift on this cam. Note, however, that with the OE springs, there is virtually no chance that the OE pushrod is going to flex, so this is another money saving strategy. I'm not saying that saving money is bad, quite the contrary, but that it's not particularly easy to squeeze more power out of Chevy's design, which offers limited headroom for modifications, when using the OE parts. So, to your point, adding better quality springs as well as upgraded LS7 lifters and quality pushrods to the TSP cam kit would dramatically increase its price. IMHO, however, this is the only sensible approach, as the valvetrain is the worse possible place to cut corners.
There is a part time drag racer and full time head porter that I follow. When he ports a set of LS heads, 90% of the time he installs PAC springs and he likes anywhere from 135# to 155# of seat pressure for street hydraulic roller cams. He notes that not all hydraulic roller lifters can tolerate 155# of seat pressure and also that lifter functionality is highly dependent on the oil viscosity used in the engine. Meanwhile, OE LS6 springs offer only 90# of seat pressure!
The PAC 1218 / 1218x springs offer 130# to 140# of seat pressure so these would seem to fall right into the sweet spot of adequate spring pressure, without overwhelming the lifter.
Note that all of these comments assume that the installed heights of the springs are properly adjusted and verified.
There is a part time drag racer and full time head porter that I follow. When he ports a set of LS heads, 90% of the time he installs PAC springs and he likes anywhere from 135# to 155# of seat pressure for street hydraulic roller cams. He notes that not all hydraulic roller lifters can tolerate 155# of seat pressure and also that lifter functionality is highly dependent on the oil viscosity used in the engine. Meanwhile, OE LS6 springs offer only 90# of seat pressure!
The PAC 1218 / 1218x springs offer 130# to 140# of seat pressure so these would seem to fall right into the sweet spot of adequate spring pressure, without overwhelming the lifter.
Note that all of these comments assume that the installed heights of the springs are properly adjusted and verified.
This is one of the reasons I use the PAC 1218 in my car. Its actually a softer spring rate, but a taller spring. This makes more seat pressure, but about the same pressure open as the LS6 spring (like 296 vs 308 or something). Still gentle on lifters and handles high RPM well.
Good info. I am on an information gathering venture for when I tear into mine, going to start at the back first however. I have learned from my younger daze doing the engine first it is pretty guaranteed the trans will last about a month before it pukes. The bad part of having a slushbox vs a stick.
02-09-2024, 05:17 PM
Replaced my stock 04 LS6 valve springs.
