[Z06] LS7 valve guide news.
02-11-2016, 02:17 PM
#1601
Team Owner
don't understand why so frequent oil analysis is being done on street cars?
Heck if it is the valves people want to monitor--it takes about as long to change the oil as it does to pull the valve covers. Just pull the valve covers look and be done with it?
If certain people like to analyze ,try to trend and correlate then that is great. This is the big data generation...I am more tactile. To each his own..makes for an interesting world
Heck if it is the valves people want to monitor--it takes about as long to change the oil as it does to pull the valve covers. Just pull the valve covers look and be done with it?
If certain people like to analyze ,try to trend and correlate then that is great. This is the big data generation...I am more tactile. To each his own..makes for an interesting world
Paralysis by analysis comes to mind...
02-11-2016, 03:48 PM
#1602
Race Director
02-11-2016, 04:30 PM
#1603
Burning Brakes
I was thinking it was rod/bearing related, considering the Pb numbers were up as well...although the newer bearings are lead free. I've yet to see any proof that wearing guides puts any Ti in the oil. In order for Ti to get in the oil from the intake valves, the CrN coating would have to first wear off. Most of the intake valves I've seen, the coating is totally intact.
02-11-2016, 05:13 PM
#1604
Pro
But I will clarify what I meant. Yes, the coating has been noted as "rough", and has been blamed for excessive intake guide wear. You'd have to wear through the CrN coating on the Ti intakes, for it to even be possible for Ti to get in the oil, from the intake guides/valves wearing against each other. I've never seen the CrN coating worn through, on any of the valves I've personally looked at. I still think it would be unlikely for much if any to make it into the oil regardless.
Blackstone was making it sound like if you get your oil checked by them, and find Ti in it, they "saved" your motor from a valve drop. If I ever found excesive Ti in my oil, my immediate thought would be the rods galling each other. Ti valve spring retainers can release a bit as well, which would go right into the oil...but a stock motor wouldn't have them.
02-11-2016, 11:39 PM
#1605
Melting Slicks
Both sets of replacement heads were/are OEM (see post 1324 in this thread). Blackstone made an assumption that the new heads had replacement guides. I wrote them back to correct their error. Anyhow, I just thought it seemed interesting that for the period where the original exhaust guides wore, there was no Ti reading and a slightly above avg iron reading, but for the period where the first set of OEM replacement heads were installed and those intake guides wore (but the exhaust didn't), there was a Ti reading and a much larger iron reading in the oil analysis.
02-12-2016, 12:44 AM
#1606
Le Mans Master
I'm not exactly following...
But I will clarify what I meant. Yes, the coating has been noted as "rough", and has been blamed for excessive intake guide wear. You'd have to wear through the CrN coating on the Ti intakes, for it to even be possible for Ti to get in the oil, from the intake guides/valves wearing against each other. I've never seen the CrN coating worn through, on any of the valves I've personally looked at. I still think it would be unlikely for much if any to make it into the oil regardless.
Blackstone was making it sound like if you get your oil checked by them, and find Ti in it, they "saved" your motor from a valve drop. If I ever found excesive Ti in my oil, my immediate thought would be the rods galling each other. Ti valve spring retainers can release a bit as well, which would go right into the oil...but a stock motor wouldn't have them.
But I will clarify what I meant. Yes, the coating has been noted as "rough", and has been blamed for excessive intake guide wear. You'd have to wear through the CrN coating on the Ti intakes, for it to even be possible for Ti to get in the oil, from the intake guides/valves wearing against each other. I've never seen the CrN coating worn through, on any of the valves I've personally looked at. I still think it would be unlikely for much if any to make it into the oil regardless.
Blackstone was making it sound like if you get your oil checked by them, and find Ti in it, they "saved" your motor from a valve drop. If I ever found excesive Ti in my oil, my immediate thought would be the rods galling each other. Ti valve spring retainers can release a bit as well, which would go right into the oil...but a stock motor wouldn't have them.
If you have high Ti readings, it's not from the intake valves. 
02-12-2016, 12:30 PM
#1608
Race Director
Great work by Hib.
02-12-2016, 02:29 PM
#1610
Burning Brakes
02-13-2016, 05:17 PM
#1611
Pro Mechanic
Pro Mechanic
Thread Starter
Looks like Hib Halverson updated the article on this subject at the Corvette Action Center - page 18 - 26:
http://www.corvetteactioncenter.com/...te-ls7-engine/
http://www.corvetteactioncenter.com/...te-ls7-engine/
The third, and likely final edtion, of "Ruthless Pursuit of Power Lucky Seven Edition" has been posted on another web site. I can't give the name or a link because, lasst year, I was advised by a CF SuperModerator if I didn't stop doing that, I'd get banned from the CF but, fortunately, someone else has listed the link.
Up to page 17, there are small changes everywhere in the article. When coverage of the valve guide problem begins on p.18, the rest of the article is vastly different content than was in the 2nd Edition.
At a later date, we'll rewrite the sidebar on how DIYs can check their clearance with the heads on the engine to reflect GM's discrediting the old "wiggle test".
The third installment of the series, an article on modifying stock LS7 head castings for better performance is also coming but it will be six-months to a year or so before that's ready. The problem is that the LS7 articles do not pay anything, so I have to schedule work on them at times when money jobs are slow.
No doubt people here will love or hate what I say in that story but, love
or hate
....post your comments.
The following 3 users liked this post by Hib Halverson:
02-13-2016, 05:23 PM
#1612
Pro Mechanic
Pro Mechanic
Thread Starter
The problem with trying ID a guide wear issue with oil analysis is the same to wear metals will appear if there is a problem with the sides of the big ends of the rods wearing. You'll see high iron from the Ti dust abrading the fillets of the crank journals and you'll see high Ti from as the rod coating wears through and Ti "dust" develops.
I agree that high iron and high Ti may indicate guide wear, but high iron and high Ti can, also, indicate a problem with the connecting rods.
Thus, oil analysis cannot be a conclusive diagnosis of guide wear.
You still have to measure the guides.
02-13-2016, 08:32 PM
#1613
Race Director
Well, you're wrong.
The problem with trying ID a guide wear issue with oil analysis is the same to wear metals will appear if there is a problem with the sides of the big ends of the rods wearing. You'll see high iron from the Ti dust abrading the fillets of the crank journals and you'll see high Ti from as the rod coating wears through and Ti "dust" develops.
I agree that high iron and high Ti may indicate guide wear, but high iron and high Ti can, also, indicate a problem with the connecting rods.
Thus, oil analysis cannot be a conclusive diagnosis of guide wear.
You still have to measure the guides.
The problem with trying ID a guide wear issue with oil analysis is the same to wear metals will appear if there is a problem with the sides of the big ends of the rods wearing. You'll see high iron from the Ti dust abrading the fillets of the crank journals and you'll see high Ti from as the rod coating wears through and Ti "dust" develops.
I agree that high iron and high Ti may indicate guide wear, but high iron and high Ti can, also, indicate a problem with the connecting rods.
Thus, oil analysis cannot be a conclusive diagnosis of guide wear.
You still have to measure the guides.
If you are saying that finding high metals indicates either (serious) problem A or (serious) problem B. Then are you saying "don't bother with it?"
For my simple way of looking at this I'd say "right on" I'll do the analysis and maybe find either one of the problems is "developing".
So if it's not a SOLE conclusive diagnostic of guide wear, so what? Could be one of two bad problems with the engine. All the more reason to do it.
Just making a point of logic, not starting an argument, you know more than pretty much the collective knowledge of everyone posting on the thread, and thanks for doing it.
02-14-2016, 01:12 AM
#1614
Team Owner
Yep.
The third, and likely final edtion, of "Ruthless Pursuit of Power Lucky Seven Edition" has been posted on another web site. I can't give the name or a link because, lasst year, I was advised by a CF SuperModerator if I didn't stop doing that, I'd get banned from the CF but, fortunately, someone else has listed the link.
Up to page 17, there are small changes everywhere in the article. When coverage of the valve guide problem begins on p.18, the rest of the article is vastly different content than was in the 2nd Edition.
At a later date, we'll rewrite the sidebar on how DIYs can check their clearance with the heads on the engine to reflect GM's discrediting the old "wiggle test".
The third installment of the series, an article on modifying stock LS7 head castings for better performance is also coming but it will be six-months to a year or so before that's ready. The problem is that the LS7 articles do not pay anything, so I have to schedule work on them at times when money jobs are slow.
No doubt people here will love or hate what I say in that story but, love or hate....post your comments.
The third, and likely final edtion, of "Ruthless Pursuit of Power Lucky Seven Edition" has been posted on another web site. I can't give the name or a link because, lasst year, I was advised by a CF SuperModerator if I didn't stop doing that, I'd get banned from the CF but, fortunately, someone else has listed the link.
Up to page 17, there are small changes everywhere in the article. When coverage of the valve guide problem begins on p.18, the rest of the article is vastly different content than was in the 2nd Edition.
At a later date, we'll rewrite the sidebar on how DIYs can check their clearance with the heads on the engine to reflect GM's discrediting the old "wiggle test".
The third installment of the series, an article on modifying stock LS7 head castings for better performance is also coming but it will be six-months to a year or so before that's ready. The problem is that the LS7 articles do not pay anything, so I have to schedule work on them at times when money jobs are slow.
No doubt people here will love or hate what I say in that story but, love
or hate....post your comments.http://www.corvetteactioncenter.com/...te-ls7-engine/
DH
Last edited by Dirty Howie; 02-14-2016 at 01:15 AM.
02-14-2016, 01:14 AM
#1615
Pro Mechanic
Pro Mechanic
Thread Starter
Sheesh.
This is getting a bit exhausting.
No, "froggy47", I'm not saying...
Periodic oil analysis is a tool one can use to monitor durability. There are a number of valuable indicators you can get from Blackstone Labs oil analysis other than just "wear metals" and, for that reason, I send a sample to Blackstone every oil change.
I am saying that, using high iron and Ti numbers in combination as an indicator of guide wear then proceeding down that road, is a fool's errand.
If I got an oil analysis back showing high iron and high Ti, I'd do a "heads'-on" test for guide clearance using a test indicator. As soon as I found a valve or two with a lot of clearance, I'd pull the heads and check guide clearance on all 16 using either GM's clearance measuring procedure or a Sunnen P310.
If I did not find any high clearances in a "heads-on" test, then I'd pull the motor, tear it down and inspect the sides of the big ends of the rods.
This is getting a bit exhausting.
No, "froggy47", I'm not saying...
Don't bother with it.
I am saying that, using high iron and Ti numbers in combination as an indicator of guide wear then proceeding down that road, is a fool's errand.
If I got an oil analysis back showing high iron and high Ti, I'd do a "heads'-on" test for guide clearance using a test indicator. As soon as I found a valve or two with a lot of clearance, I'd pull the heads and check guide clearance on all 16 using either GM's clearance measuring procedure or a Sunnen P310.
If I did not find any high clearances in a "heads-on" test, then I'd pull the motor, tear it down and inspect the sides of the big ends of the rods.
02-14-2016, 12:39 PM
#1617
Safety Car
I'm glad you guys touched on the subject of oil analysis and would like to know what you think about my situation. I have a 2013 427 that I bought with 2800 miles on it with a fresh oil change. At 5600 I tested the oil and had five parts of titanium per million, and 46 parts of iron. I decided to do a second test at 1400 miles and now it is down to one part per million on the titanium and 17 for the iron. It appears to be getting better and I'll do another check at 2800 miles for an apples to apples comparison. My theory is the rods were rubbing together and now the clearances are wider creating a less titanium dust. So now the question is how much damage did it do to my engine, and if the titanium goes away in my OK? And second should I go to the dealer with this information or wait? Already met with the local dealer and he seems pretty cool and will work with me if I have any issues, thoughts appreciated!
Last edited by vertC6; 02-14-2016 at 02:35 PM.
02-14-2016, 08:01 PM
#1618
Burning Brakes
The third installment of the series, an article on modifying stock LS7 head castings for better performance is also coming but it will be six-months to a year or so before that's ready. The problem is that the LS7 articles do not pay anything, so I have to schedule work on them at times when money jobs are slow.
No doubt people here will love or hate what I say in that story but, love
or hate....post your comments.Love the articles.
Thanks,
Scott
02-15-2016, 10:59 PM
#1619
Pro Mechanic
Pro Mechanic
Thread Starter
I'll put CHE's manganese bronze guides in the heads. I'll use stock valves but with the intakes superfinished by Del West. I'll have the guides clearanced to, oh, say about .0015 and I'll have seat runout held to .001 to .0015. I'll use stock valve seals, Katech's valve springs and their Ti retainers.
no milling and stock head gaskets. My own calibration.
My guess is I'll gain 20-25-hp with that and, perhaps, move the power peak up a bit.
My ultimate goal was 600-hp with stock cam and exhaust but, after researching a bit, I think that's too optimistic. I've dropped my target to 580-hp SAE.
Lastly, my goal here is to do the most I can with production head castings and I want to do that "just because". I realize that if I went to just the right aftermarket LS7 head, I could do even better.
Last edited by Hib Halverson; 02-16-2016 at 10:16 AM. Reason: added content
02-16-2016, 05:47 AM
#1620
Yep. I'll take a set of stock bare castings and have them ported by one of the bigger head services. I'm partial to Texas Speed at this point, but I haven't decided.
I'll put CHE's manganese bronze guides in the heads. I'll use stock valves but with the intakes superfinished by Del West. I'll have the guides clearanced to, oh, say about .0015. I'll use Katech's valve springs and their Ti retainers.
no milling and stock head gaskets. My own calibration.
My guess is I'll gain 25-30-hp with that and perhaps move the power peak up a bit.
I'll put CHE's manganese bronze guides in the heads. I'll use stock valves but with the intakes superfinished by Del West. I'll have the guides clearanced to, oh, say about .0015. I'll use Katech's valve springs and their Ti retainers.
no milling and stock head gaskets. My own calibration.
My guess is I'll gain 25-30-hp with that and perhaps move the power peak up a bit.
Sounds like a plan.