Give me a break - bad valve guides 3 times < 49000 miles
10-16-2021, 11:00 AM
#81
Racer
So I have an '08 with about 25k miles on it which I bought new. All stock except for ZR1 mufflers. I was planning on keeping it stock and enjoying it for what it is for a very long time. 505hp is fine with me. I have an extended warranty that runs out next august. The plan was to take it to shop #2 and have them rework the heads after the warranty runs out. After reading this thread, it appears that replacing the heads with aftermarket is the best bet. What is the best bet for aftermarket heads. Remember, looking for longevity, not HP.
Also, aftermarket heads mean a tune. They flow considerably more which you ECU can’t adapt properly for. That won’t keep your car « stock ». Heads properly machines will address your concern.
Last edited by herwawan; 10-16-2021 at 11:02 AM.
10-16-2021, 11:23 AM
#82
Drifting
One negative feedback is enough to make you change your entire strategy despite a majority of satisfied customers? Doesn’t discount OP story at all, but that’s a bit extreme. I even feel like I should stop reading the forum because of the amount of fear that exist over here.
Also, aftermarket heads mean a tune. They flow considerably more which you ECU can’t adapt properly for. That won’t keep your car « stock ». Heads properly machines will address your concern.
Also, aftermarket heads mean a tune. They flow considerably more which you ECU can’t adapt properly for. That won’t keep your car « stock ». Heads properly machines will address your concern.
Last edited by loflite; 10-16-2021 at 11:27 AM.
10-16-2021, 11:49 AM
#83
Drifting
Member Since: Dec 2017
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2023 Corvette of the Year Finalist - Unmodified
2022 C6 of the Year Winner - Unmodified
I have shop #2 heads in my otherwise stock LS7 (except a tune, +40hp)
My local LS expert/tuner shop confirms that if you stay stock cam it should be fine, otherwise it will become a maintenance item.
treat it nice, warm up gently, no lugging and use an oil with at least 1000ppm zinc.
I run mine at track days staying between 4-7k much of the time. It’s fine
My local LS expert/tuner shop confirms that if you stay stock cam it should be fine, otherwise it will become a maintenance item.
treat it nice, warm up gently, no lugging and use an oil with at least 1000ppm zinc.
I run mine at track days staying between 4-7k much of the time. It’s fine
Last edited by tommyc6z06; 10-21-2021 at 10:47 AM.
10-16-2021, 11:58 AM
#84
Instructor
At the risk of jinxing myself (about 150mi on a fresh set of what we're now calling shop #2 heads), you gotta remember that the people whose cars *aren't* broken don't post "HAY GUYS GUESS WHAT MY CAR'S NOT BROKEN".
FWIW, the set I took off (warranteed stockers) were "wow we're amazed they're still in one piece" after less than 20K miles. Admittedly, the last 2K or so of those were spent mostly on track.
FWIW, the set I took off (warranteed stockers) were "wow we're amazed they're still in one piece" after less than 20K miles. Admittedly, the last 2K or so of those were spent mostly on track.
Last edited by kyle242gt; 10-16-2021 at 11:58 AM.
10-16-2021, 09:33 PM
#86
GM will never disclose their data. Even the Camaros that got the LS7 engines had the problem. Hib Haberson measured warranty replacement heads for his Z brand new in 2013 and they were out of spec. I do not know if LS7 heads are still being made, but I am sure Linimar is doing them the same way if they are still in production.
As an aside, Linimar got the GM contract for Z06 e-difs delivered to Bowling Green "ready for installation". Unfortunately they short filled the difs with fluid and a good number of them failed early (a quality supplier??). One CA buyer took BG delivery and only got as far at TX before the dif failed, stranding him on his trip home.
As an aside, Linimar got the GM contract for Z06 e-difs delivered to Bowling Green "ready for installation". Unfortunately they short filled the difs with fluid and a good number of them failed early (a quality supplier??). One CA buyer took BG delivery and only got as far at TX before the dif failed, stranding him on his trip home.
10-16-2021, 10:04 PM
#87
I expect THAT rocker shaft system (with the roller bearing rocker arm tips) - will resolve the side loading issue !!!
As the rocker pushes down on the valve - the tip of the rocker "slides" along the valve tip. The side loading is proportionate to the amount of force being applied to lift the valve, and the coefficient of friction between the rocker arm tip and the tip of the valve stem. The side load typically gets worse as the valve gets to max lift - when the spring is most compressed. This is why guide wear is typically "worst" when the wear is checked at max lift - vs at just barely open... As I said in post 34 - If the pushrod is not the correct length (and the "correct length" will vary due to things like milled heads, different cam "base circles" etc. etc.) the geometry gets worse (read that as there is more rocker arm sliding across the valve tip), and the guide wear increases. There is a good discussion about this on the Comp Cams website.
As the rocker pushes down on the valve - the tip of the rocker "slides" along the valve tip. The side loading is proportionate to the amount of force being applied to lift the valve, and the coefficient of friction between the rocker arm tip and the tip of the valve stem. The side load typically gets worse as the valve gets to max lift - when the spring is most compressed. This is why guide wear is typically "worst" when the wear is checked at max lift - vs at just barely open... As I said in post 34 - If the pushrod is not the correct length (and the "correct length" will vary due to things like milled heads, different cam "base circles" etc. etc.) the geometry gets worse (read that as there is more rocker arm sliding across the valve tip), and the guide wear increases. There is a good discussion about this on the Comp Cams website.
10-16-2021, 10:29 PM
#89
Race Director
The e-Dif problem was for the C7 Zs, so contract awarded years after Linamar continued to deliver out of spec heads that GM accepted and let customers deal with it.
10-17-2021, 11:43 AM
#90
Team Owner
Member Since: Oct 2004
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St. Jude Donor '05
If I were to have any heads reworked they would get sent to Richard over at WCCH and nowhere else.
Known him for decades, he and Dave run a pretty good biz there. Couple of honest guys who know their chit.
background goes a lot further than just a nice machine shop
Known him for decades, he and Dave run a pretty good biz there. Couple of honest guys who know their chit.
background goes a lot further than just a nice machine shop
10-17-2021, 12:34 PM
#91
Race Director
My K501 cammed Z06 (.658/.660 lift, 593/513 rwhp/tq) done by WCCH at 46K miles with CHE bronze guides went back to them 11K miles later while the bottom end got forged and the guides measured .0011-.0016", not far off when they were done 2 years before, OEM rockers, PSI 1511 springs, lightweight valves, easy street use and 4-7K RPM for track events when oil is 160*F+ before full throttle.
10-17-2021, 12:39 PM
#92
Instructor
My K501 cammed Z06 (.658/.660 lift, 593/513 rwhp/tq) done by WCCH at 46K miles with CHE bronze guides went back to them 11K miles later while the bottom end got forged and the guides measured .0011-.0016", not far off when they were done 2 years before, OEM rockers, PSI 1511 springs, lightweight valves, easy street use and 4-7K RPM for track events when oil is 160*F+ before full throttle.
Last edited by Blackship; 10-17-2021 at 12:39 PM.
10-18-2021, 09:34 AM
#95
Pro
The wear on your titanium valves on the seat was most likely due to valve float with those springs - not valve lapping.
Switching to an aftermarket lifter will make no difference in the amount of oil the valve stem sees - so stock or Johnson here makes 0 difference.
Waiting for engine to warm up to 150+ to pass 3000rpm is pointless and potentially even more harmful to the engine. Low rpm and cold oil is way worse for hydrodynamic bearings than higher rpm and cold oil. So for those of you lugging your engine at 1000rpm going down the road when cold this is a warning for you that you are doing wayyyyy more damage than being at 2k+.
Switching to an aftermarket lifter will make no difference in the amount of oil the valve stem sees - so stock or Johnson here makes 0 difference.
Waiting for engine to warm up to 150+ to pass 3000rpm is pointless and potentially even more harmful to the engine. Low rpm and cold oil is way worse for hydrodynamic bearings than higher rpm and cold oil. So for those of you lugging your engine at 1000rpm going down the road when cold this is a warning for you that you are doing wayyyyy more damage than being at 2k+.
That literally makes zero sense. Explain how "lugging your engine at 1000 rpm going down the road when cold this is a warning for you that you are doing wayyyyy more damage than being at 2k+"
People that do this day in and day out don't say stuff like this because it has no technical merit.
If you are going to rev the engine up, you should probably wait till oil temps come up a bit. There is a reason that M cars slowly bring the redline up to the maximum as the fluids come up to temp. Since oil takes quite a bit longer to come up than coolant, it would make sense to bade it off oil temp.
10-18-2021, 09:38 AM
#96
Pro
The BIGGEST contributors IMO to valve and guide wear is the combo of a longer valve, short (compared) guides and a non-roller tip rocker that tends to scrub and "pull) the top of the lash cap at lifts higher than stock. I would never reinstall a stock scrub-tip rocker on a decent build. A roller tip lets the rocker compress the spring and open the valve WITHOUT pulling at it and side loading it--the wheel rotates and friction is reduced.
10-18-2021, 10:36 AM
#97
That literally makes zero sense. Explain how "lugging your engine at 1000 rpm going down the road when cold this is a warning for you that you are doing wayyyyy more damage than being at 2k+"
People that do this day in and day out don't say stuff like this because it has no technical merit.
If you are going to rev the engine up, you should probably wait till oil temps come up a bit. There is a reason that M cars slowly bring the redline up to the maximum as the fluids come up to temp. Since oil takes quite a bit longer to come up than coolant, it would make sense to bade it off oil temp.
People that do this day in and day out don't say stuff like this because it has no technical merit.
If you are going to rev the engine up, you should probably wait till oil temps come up a bit. There is a reason that M cars slowly bring the redline up to the maximum as the fluids come up to temp. Since oil takes quite a bit longer to come up than coolant, it would make sense to bade it off oil temp.
Last I checked 2k is pretty far away from redline and a BMW is also not a good marker for reliability.
GM also does the increased redline as temps go up - we aren’t talking about max rpm here…we are talking about barely off idle loads.
10-18-2021, 04:13 PM
#98
Race Director
[QUOTE=Apocolipse;1604180439]
Last I checked 2k is pretty far away from redline and a BMW is also not a good marker for reliability.[/QUOTE]
I sold my E36 M3 at 169K miles to a guy that was going to transplant the engine into a 318TI. The engine used M1 5W-30, had a leakdown test at 133K miles that was impressive for an engine with 10K lines on it, had 40 hard track days, was chipped at 155K miles which really enhanced the mid-range torques and was running very well when sold. I would say that is quite reliable.
Last I checked 2k is pretty far away from redline and a BMW is also not a good marker for reliability.[/QUOTE]
I sold my E36 M3 at 169K miles to a guy that was going to transplant the engine into a 318TI. The engine used M1 5W-30, had a leakdown test at 133K miles that was impressive for an engine with 10K lines on it, had 40 hard track days, was chipped at 155K miles which really enhanced the mid-range torques and was running very well when sold. I would say that is quite reliable.
10-18-2021, 05:39 PM
#99
Melting Slicks
Pro Mechanic
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OK, it's off topic, but after 35 years as a BMW tech, I'll weigh in on the BMW vs. reliability issue.
4&6 cyls up to ~2006 were pretty much bulletproof. Except for the E46 M3 motor... excessive rod bearing loading + overly ambitious redline = grenade.
V8s till around 1998 were mostly solid, later ones not so great...
Later 6s have Rube Goldberg's variable cam lift mechanism. Mostly reliable, but...
BMW was proud to remind everyone that their middle name was MOTOR. Usuallyit was the most durable part of the car.
But then there's the rest of the car... don't own one out of warranty!
E36 3 series was a definite high point. I'd see heavily tracked 200K+ mile examples regularly through the shop.
A good customer had an E46 330i with 330K miles... ran great, still solid as hell. Needed new cats to pass smog, but it was hard to justify putting $2K+ into it...
My wife and I both have similar 330s. 220k on hers, 130k on mine. They've both been dead *** reliable.
4&6 cyls up to ~2006 were pretty much bulletproof. Except for the E46 M3 motor... excessive rod bearing loading + overly ambitious redline = grenade.
V8s till around 1998 were mostly solid, later ones not so great...
Later 6s have Rube Goldberg's variable cam lift mechanism. Mostly reliable, but...
BMW was proud to remind everyone that their middle name was MOTOR. Usuallyit was the most durable part of the car.
But then there's the rest of the car... don't own one out of warranty!
E36 3 series was a definite high point. I'd see heavily tracked 200K+ mile examples regularly through the shop.
A good customer had an E46 330i with 330K miles... ran great, still solid as hell. Needed new cats to pass smog, but it was hard to justify putting $2K+ into it...
My wife and I both have similar 330s. 220k on hers, 130k on mine. They've both been dead *** reliable.