[Z06] Need advice! Scared of blowing my LS7!!
12-09-2013, 02:21 PM
#21
I think you're overthinking it 
Again... "The exhaust valves wiggled 25 thousandths!". Pretty much speaks for itself despite the additional commentary, but we can wait to hear it from the source soon enough, I'd imagine. I just wanted to jump in since it seemed that the commentary was going off track based on a non-literal read (OMG, .025 guide clearance, worst ever, new record, the end is near!!!
).
And then keep in mind we don't know (yet) how this particular wiggle test was done... I've seen people stick the valve in upside down and wiggle the valve face, some 3" above the guide (getting wiggle that is probably 4x the actual guide clearance).
.
Again... "The exhaust valves wiggled 25 thousandths!". Pretty much speaks for itself despite the additional commentary, but we can wait to hear it from the source soon enough, I'd imagine. I just wanted to jump in since it seemed that the commentary was going off track based on a non-literal read (OMG, .025 guide clearance, worst ever, new record, the end is near!!!
).And then keep in mind we don't know (yet) how this particular wiggle test was done... I've seen people stick the valve in upside down and wiggle the valve face, some 3" above the guide (getting wiggle that is probably 4x the actual guide clearance).
.
Last edited by Mark2009; 12-09-2013 at 02:23 PM.
12-09-2013, 02:55 PM
#22
If he was referring to the wiggle measurements overall then "tight" would actually be .002 - .005, or 2 - 5 thousandths. That's why I was asking for more clarification since it is unclear why he would compare actual clearance measurements to wiggle measurements (which need to be converted.)
He described .025" of "wiggle". About 3 times the maximum you'd want to see.
Dividing that by 2 and subtracting .0005" would give a stem to guide clearance of .0120". (.0125-.0005).
The production spec for stem to guide clearance is .001"-0026" on the exhaust side. Service limit is .0037".
The breakdown can be seen in this previously posted link by Despicable Z http://www.bakesonline.com/images/Me...epairSpecs.pdf
So if he's at .0120" of actual clearance, that's a little over 3 times the maximum allowed before being out of spec. and up to 10 times the production spec.
You see someone at .0060-.0090 of stem to guide clearance, that's bad considering that .0037" is the limit.
.0120" of stem to guide clearance is severely out of spec.
Last edited by '06 Quicksilver Z06; 12-09-2013 at 08:06 PM.
12-09-2013, 04:43 PM
#23
Team Owner
if that's what they were, then that would probably be a "record" in here.
And I also agree that the OP should call LG. Surely they could look up his VIN and see what was done. And thanks to LG for sponsoring the Corvette Challenge
DH
12-09-2013, 09:26 PM
#24
Sorry for the wait. Hopefully the first one works if you click on the pic. If not there is a link to click on. Here it is:
http://s27.photobucket.com/user/coxt...9282c.mp4.html
Also, I looked at the receipt and the stock two peice exhaust valves were replaced with Ferrea LS7 exhaust valves. And it was done in May of 2010. Regardless the miles were still accurate as to when the work was done. The shop said they had not known about the issue otherwise they would have replaced it right then and there when they replaced the valves and ported the heads, etc.
http://s27.photobucket.com/user/coxt...9282c.mp4.html
Also, I looked at the receipt and the stock two peice exhaust valves were replaced with Ferrea LS7 exhaust valves. And it was done in May of 2010. Regardless the miles were still accurate as to when the work was done. The shop said they had not known about the issue otherwise they would have replaced it right then and there when they replaced the valves and ported the heads, etc.
Last edited by JCox23; 12-09-2013 at 09:38 PM.
12-09-2013, 09:52 PM
#25
Sorry for the wait. Hopefully the first one works if you click on the pic. If not there is a link to click on. Here it is:
http://s27.photobucket.com/user/coxt...9282c.mp4.html
Also, I looked at the receipt and the stock two peice exhaust valves were replaced with Ferrea LS7 exhaust valves. And it was done in May of 2010. Regardless the miles were still accurate as to when the work was done. The shop said they had not known about the issue otherwise they would have replaced it right then and there when they replaced the valves and ported the heads, etc.
http://s27.photobucket.com/user/coxt...9282c.mp4.html
Also, I looked at the receipt and the stock two peice exhaust valves were replaced with Ferrea LS7 exhaust valves. And it was done in May of 2010. Regardless the miles were still accurate as to when the work was done. The shop said they had not known about the issue otherwise they would have replaced it right then and there when they replaced the valves and ported the heads, etc.
12-09-2013, 10:24 PM
#28
I believe so, yes.
And to the OP, sorry to high jack your thread. I was just wanting to show you that these things are definitely worth checking because even as bad as mine were, there were no signs of them going out and yet these look like they could've dropped a valve at any minute. Call LG and see if they have record of doing your guides, they should. If not, pull them immediately and send them to a reputable shop and have them replaced! Or a more expensive option is just replacing the heads altogether. Good luck!
And to the OP, sorry to high jack your thread. I was just wanting to show you that these things are definitely worth checking because even as bad as mine were, there were no signs of them going out and yet these look like they could've dropped a valve at any minute. Call LG and see if they have record of doing your guides, they should. If not, pull them immediately and send them to a reputable shop and have them replaced! Or a more expensive option is just replacing the heads altogether. Good luck!
12-10-2013, 12:19 AM
#29
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Called LG and they can't tell me anything without the original owners name. They don't keep records with the Vin. 
Also called 4 Chevy dealers and they all thought I was crazy when asking about the wiggle test. I explained it to them and they all said it wasn't something they could do there. I am not mechanically inclined enough to even think about doing it myself.
Also called 4 Chevy dealers and they all thought I was crazy when asking about the wiggle test. I explained it to them and they all said it wasn't something they could do there. I am not mechanically inclined enough to even think about doing it myself.
12-10-2013, 12:30 AM
#30
Luckily the shop new my car from the previous owners name. But it's worth it to find a reputable shop and have your car checked out. Cheap insurance compared to a $10K engine! I have to drive 3-6 hours depending on the shop and what I want done. It's not easy living out in the middle of nowhere trust me haha.
12-10-2013, 01:31 AM
#32
Safety Car
I fixed mine at 3500 miles, or so.
Good luck.
12-10-2013, 03:39 PM
#33
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Well, I talked to a guy at LG today that was super helpful. He remembered my car and the prevoius owner! He told me all about the car. Unfortuatly the heads were never done because they didn't know about the problem back then. So it will need something done soon to insure nothing goes boom!
He also recommended using Redline 0w40 oil instead of the mobile one. He said that the mobile one doensn't have the same lubricant that it had originally. Mobile One have changed there oil contents. And they feel thats a major reason why the LS7 has had the problems its had.
He also recommended using Redline 0w40 oil instead of the mobile one. He said that the mobile one doensn't have the same lubricant that it had originally. Mobile One have changed there oil contents. And they feel thats a major reason why the LS7 has had the problems its had.
12-10-2013, 03:49 PM
#34
Race Director
Well, I talked to a guy at LG today that was super helpful. He remembered my car and the prevoius owner! He told me all about the car. Unfortuatly the heads were never done because they didn't know about the problem back then. So it will need something done soon to insure nothing goes boom!
He also recommended using Redline 0w40 oil instead of the mobile one. He said that the mobile one doensn't have the same lubricant that it had originally. Mobile One have changed there oil contents. And they feel thats a major reason why the LS7 has had the problems its had.
He also recommended using Redline 0w40 oil instead of the mobile one. He said that the mobile one doensn't have the same lubricant that it had originally. Mobile One have changed there oil contents. And they feel thats a major reason why the LS7 has had the problems its had.
Interesting comment about the oil. I'm sure that will open up a whole new can of worms around these parts. Since I changed to Amsoil after my heads were replaced under warranty, I'm hoping there's some truth to that theory. Best of luck.
12-10-2013, 04:23 PM
#35
Drifting
Well, I talked to a guy at LG today that was super helpful. He remembered my car and the prevoius owner! He told me all about the car. Unfortuatly the heads were never done because they didn't know about the problem back then. So it will need something done soon to insure nothing goes boom!
He also recommended using Redline 0w40 oil instead of the mobile one. He said that the mobile one doensn't have the same lubricant that it had originally. Mobile One have changed there oil contents. And they feel thats a major reason why the LS7 has had the problems its had.
He also recommended using Redline 0w40 oil instead of the mobile one. He said that the mobile one doensn't have the same lubricant that it had originally. Mobile One have changed there oil contents. And they feel thats a major reason why the LS7 has had the problems its had.
12-10-2013, 04:26 PM
#36
Well, at least you have the info you need to move forward. Interesting comment about the oil. I'm sure that will open up a whole new can of worms around these parts. Since I changed to Amsoil after my heads were replaced under warranty, I'm hoping there's some truth to that theory. Best of luck.
Interesting comment about the oil. I'm sure that will open up a whole new can of worms around these parts. Since I changed to Amsoil after my heads were replaced under warranty, I'm hoping there's some truth to that theory. Best of luck. Personally I am going to try temporarily covering the oil cooler up and switching to Amsoil 0W 30 and see if that helps.
12-10-2013, 06:17 PM
#37
Race Director
Oh I've already seen that can of worms opened lol. I read a pretty lengthy thread about it over Thanksgiving that ultimately ended up being shut down because people were arguing too much. I think it was pretty much agreed on that because of the oil cooler on our cars the oil never gets up to the proper temperature unless you're just beating the hell out of it at a track so that's why we need to switch to a 0w 30 or 0w 40 weight. It's even been suggested to cover up the oil dealer or delete it.
Personally I am going to try temporarily covering the oil cooler up and switching to Amsoil 0W 30 and see if that helps.
Personally I am going to try temporarily covering the oil cooler up and switching to Amsoil 0W 30 and see if that helps.
I just took delivery today of the Unbalanced Engineering oil cooler/reservoir "blanket" kit. It looks pretty well made. Once our recent snowfall is fully melted I'll get out and see how well it works. During winter time here it can be a challenge to reach 160 degrees of indicated oil temp. The kit may come back off during the summer since it's typically well over 90. If you're interested I'll post my winter results- or I can give you the temp chart info provided with the kit.
12-10-2013, 08:04 PM
#38
