[Z06] Heads guides wore out again...
09-01-2016, 03:59 PM
#41
Team Owner
That maybe a small contributing factor, but the later models have the water cooled systems and the same issue.
09-01-2016, 04:11 PM
#42
We know why the stock motors for the above years have valve guides out of spec, because the heads where not machined correctly in the first place.
09-01-2016, 06:29 PM
#43
Melting Slicks
Thread Starter
The spare heads that I have ready are off an 10 model with 15 20k on them when I bought them the guides were so loose that it was wobbling Darin said that was the worst he has seen by far.....
09-02-2016, 10:51 AM
#44
Melting Slicks
Thread Starter
Ok guys update springs look good plenty of pressure, Pac golds lasted awesome ferrea valves look great he said the guides were only off all the guides could be run again they do to have .0015 taper so that's out of Tolerance buy a half of thousands. They need replaced but they are far from shot. They have .0015 to as much as .002 clearances. That's totally except able limits and well inside the tolerance. So these are the actual findings with everything off and measured by Darin..thanks again guys these heads will be for sale they will be freshened up for the person pm if anybody is interested in them....
09-02-2016, 12:11 PM
#45
Le Mans Master
Ok, trying to decode your last post.
So, upon further inspection, you are saying the heads that you posted about in this thread do NOT have worn-out guides after all, yes??
If so, how did you conclude there was an issue, the reason why you posted this thread??
So, upon further inspection, you are saying the heads that you posted about in this thread do NOT have worn-out guides after all, yes??
If so, how did you conclude there was an issue, the reason why you posted this thread??
Last edited by Dan_the_C5_Man; 09-02-2016 at 12:11 PM.
09-02-2016, 12:19 PM
#46
Intermediate
Guides not wore out.
Just checked my heads guides are toast lucky I decided to check them after 20k miles theses dis not have bronze guides so that theory is true no pm guides. Oil analysis sent off yesterday car is not drag raced so Gm guides affect only what years again smh ill keep everone updated on my new set up....luckily I have a extra set of heads ready and cam.....
I received the heads in question yesterday, tore them down and measured the guides. When they where brought in years ago they where almost new. They had .0015 clearance with about .0005 taper. They now have .0016-.0018 with .0015 taper on the worst guide and the rest have about .001. Yes, they are wore but they are not totally "wear out". I will note that the end exhaust ports are always the worst because of lack of water circulation in that part of the head. #2 #8 exhaust ports always wear more than the rest.
These are stock guides and at the time of rebuild many years ago I did not replace the guides because the guide issue was not a proven fact at that that time and the guides where great. These heads came from 21st century and they did a great job on them! I just freshened them up and sent them down the road. Now days when it come to guide wear on the ls7, we know better and we understand that the exhaust guides can have accelerated wear especially in conjunction with high lift cams. I now replace ALL guides on LS7 heads. I use the CHE high Nickle bronze which is more than sufficient for street use. All bronze guides are not the same!!!!!!! There are over 70 different formulations of bronze guide material! If you buy the cheapest Chinese Bronze ****, its going to wear FASTER than a stock guide! I can buy bronze guides for 1.02 each or pay for the ones that will hold up and pay 5.50 to as much as 8.00 each. If its cheap, its cheap for a reason! When someone complains about how fast there bronze guides wore out, ask them if they even know what type or manufacture they used because if you use CHE and give them adequate oil flow, you wont see that ****. I dont see my heads coming back with guide wear using CHE guides as should be the case!
On another note:
How many of you guys take a razor and slice the seal on the exhaust guides? If you do this they will get the oil they need but WILL NOT contaminate the cylinder. It will also cut your guide wear in HALF no matter what material you use. I also take off the springs at the top of the seal because its a joke to run that tight a seal on a "High Performance" engine. The ONLY reason the factory cut the oil flow to the guide down to a minimum is to pass EPA standards. If the guide is wearing thats a LACK OF LUBRICATION! Get some oil to it and it will stop. We NEVER run seals on high end race engines. The more friction you have, the more oil you need. It could not be any more simple.
The following 9 users liked this post by Darin Morgan:
dmartens (03-17-2017),
FSTFRC (09-02-2016),
Hib Halverson (09-05-2016),
jp_tt_awd (09-27-2016),
rufcar (09-02-2016),
and 4 others liked this post.
09-02-2016, 12:24 PM
#47
Safety Car
09-02-2016, 12:26 PM
#48
Melting Slicks
Thread Starter
Thanks Darin on the side note heads cane from DPerformance and worked at hpe in Houston by chuck aders....the package is from 21 century...which car made good power now with this new setup I expect it to be even better...
Last edited by RamAir972003; 09-02-2016 at 12:27 PM.
09-02-2016, 12:58 PM
#49
Le Mans Master
I received the heads in question yesterday, tore them down and measured the guides. When they where brought in years ago they where almost new. They had .0015 clearance with about .0005 taper. They now have .0016-.0018 with .0015 taper on the worst guide and the rest have about .001. Yes, they are wore but they are not totally "wear out". I will note that the end exhaust ports are always the worst because of lack of water circulation in that part of the head. #2 #8 exhaust ports always wear more than the rest.
These are stock guides and at the time of rebuild many years ago I did not replace the guides because the guide issue was not a proven fact at that that time and the guides where great. These heads came from 21st century and they did a great job on them! I just freshened them up and sent them down the road. Now days when it come to guide wear on the ls7, we know better and we understand that the exhaust guides can have accelerated wear especially in conjunction with high lift cams. I now replace ALL guides on LS7 heads. I use the CHE high Nickle bronze which is more than sufficient for street use. All bronze guides are not the same!!!!!!! There are over 70 different formulations of bronze guide material! If you buy the cheapest Chinese Bronze ****, its going to wear FASTER than a stock guide! I can buy bronze guides for 1.02 each or pay for the ones that will hold up and pay 5.50 to as much as 8.00 each. If its cheap, its cheap for a reason! When someone complains about how fast there bronze guides wore out, ask them if they even know what type or manufacture they used because if you use CHE and give them adequate oil flow, you wont see that ****. I dont see my heads coming back with guide wear using CHE guides as should be the case!
On another note:
How many of you guys take a razor and slice the seal on the exhaust guides? If you do this they will get the oil they need but WILL NOT contaminate the cylinder. It will also cut your guide wear in HALF no matter what material you use. I also take off the springs at the top of the seal because its a joke to run that tight a seal on a "High Performance" engine. The ONLY reason the factory cut the oil flow to the guide down to a minimum is to pass EPA standards. If the guide is wearing thats a LACK OF LUBRICATION! Get some oil to it and it will stop. We NEVER run seals on high end race engines. The more friction you have, the more oil you need. It could not be any more simple.
These are stock guides and at the time of rebuild many years ago I did not replace the guides because the guide issue was not a proven fact at that that time and the guides where great. These heads came from 21st century and they did a great job on them! I just freshened them up and sent them down the road. Now days when it come to guide wear on the ls7, we know better and we understand that the exhaust guides can have accelerated wear especially in conjunction with high lift cams. I now replace ALL guides on LS7 heads. I use the CHE high Nickle bronze which is more than sufficient for street use. All bronze guides are not the same!!!!!!! There are over 70 different formulations of bronze guide material! If you buy the cheapest Chinese Bronze ****, its going to wear FASTER than a stock guide! I can buy bronze guides for 1.02 each or pay for the ones that will hold up and pay 5.50 to as much as 8.00 each. If its cheap, its cheap for a reason! When someone complains about how fast there bronze guides wore out, ask them if they even know what type or manufacture they used because if you use CHE and give them adequate oil flow, you wont see that ****. I dont see my heads coming back with guide wear using CHE guides as should be the case!
On another note:
How many of you guys take a razor and slice the seal on the exhaust guides? If you do this they will get the oil they need but WILL NOT contaminate the cylinder. It will also cut your guide wear in HALF no matter what material you use. I also take off the springs at the top of the seal because its a joke to run that tight a seal on a "High Performance" engine. The ONLY reason the factory cut the oil flow to the guide down to a minimum is to pass EPA standards. If the guide is wearing thats a LACK OF LUBRICATION! Get some oil to it and it will stop. We NEVER run seals on high end race engines. The more friction you have, the more oil you need. It could not be any more simple.
And you had convinced me to pull the springs on the seals (which I still haven't done yet), but cutting the lip is another step closer to the edge.
09-02-2016, 04:54 PM
#51
This is!
Pulling the springs off the exhaust guides is a MAJOR suggestion and by that same reasoning the spiraling by AHP has to help.
W/E project for sure.
The cutting, I am not sure off ,as mine is street driven?
Pulling the springs off the exhaust guides is a MAJOR suggestion and by that same reasoning the spiraling by AHP has to help.
W/E project for sure.
The cutting, I am not sure off ,as mine is street driven?
Last edited by olddragger; 09-02-2016 at 04:55 PM.
09-02-2016, 05:17 PM
#52
Safety Car
I researched this.
The amount of oil for stem lubrication is determined by the seal itself that has a wipe design. The clearance is critical and the amount of lubrication needed is pre measured in the seals gap to the stem.
No way in hell I'm toughing mine. I liked the sound bite, but if done even a hair wrong, you would be inviting issues.
Now if I had an aggressive cam and was rebuilding every 20k to install new springs, the factory amount of lubrication needed could be off the new specs
09-02-2016, 05:26 PM
#53
it would take someone with a lot of experience to know where to cut and by how much.
I don't have that. nervous about removing spring, as you say, clearances are critical. yet darin knows what he is talking about.
There is going to be some discussion about this---but valve seals are not expensive and removing the springs is not that hard.
I don't have that. nervous about removing spring, as you say, clearances are critical. yet darin knows what he is talking about.
There is going to be some discussion about this---but valve seals are not expensive and removing the springs is not that hard.
Last edited by olddragger; 09-02-2016 at 05:27 PM.
09-02-2016, 06:10 PM
#54
Safety Car
09-02-2016, 06:36 PM
#55
Ever see umbrella seals? Posi seals are for emmmisions and cats. I don't use any seals on race engines. I remove the springs and use a jeweler's file on the lips on happy street engines. Haven't tried cutting. A bit nervous that a cut might turn into a tear? Love to see how Darin does it. Learn something new every day. Good thing, seeing how I forget many things every day......
09-02-2016, 06:37 PM
#56
Safety Car
Lordy, I have learned something new on this thread. What I have learned is to never ever post to this forum from a cell phone. I have read all 3 pages and still don't have a clue what happened other than a set of heads of unknown origin with stock PM guides had some slight wear over 20,000 miles. From Darrin's response (which was apparently typed on a laptop) it appears that the guides were well within spec when he got them.
Darrin says the guides have 0.0001-0.0002 more clearance and 0.0005 more taper than when he first looked at them 20,000 miles ago. Am I missing something here? Or is this 1/10,000 more clearance a big problem?
Darrin says the guides have 0.0001-0.0002 more clearance and 0.0005 more taper than when he first looked at them 20,000 miles ago. Am I missing something here? Or is this 1/10,000 more clearance a big problem?
09-02-2016, 06:43 PM
#57
Safety Car
Thanks for the details Darin.
Darin mentioned the springs and cutting the seals in another thread a few months ago. Where were you guys then?
Darin mentioned the springs and cutting the seals in another thread a few months ago. Where were you guys then?
Last edited by Tech; 09-02-2016 at 06:43 PM.
09-02-2016, 06:57 PM
#58
Team Owner
Cutting a small knick in the seal has been a common trick forever.
09-02-2016, 08:30 PM
#59
Supporting Vendor
Just wanted to post up to make clear that our PM guides we use are not GM guides or off the shelf guides.
Our Hardened PM guides we have manufactured here locally to our specs and tolerances (proprietary to us).
We have quite a few Package 4 heads with well over 60,000 miles on them and still well within spec (still right where we set them up at).
Just wanted to make that clear.
Our Hardened PM guides are a proven guide for both street and track use. However we do recommend our Moldstar90 guides for those that are going to be doing serious track duty and those looking for an "overkill guide" for the street/strip.
Feel free to give us a call
310-326-2399
or email us at
Parts@americanheritageperformance.com
for any additional information. We are always glad to answer any questions.
http://www.americanheritageperformance.com/
Our Hardened PM guides we have manufactured here locally to our specs and tolerances (proprietary to us).
We have quite a few Package 4 heads with well over 60,000 miles on them and still well within spec (still right where we set them up at).
Just wanted to make that clear.
Our Hardened PM guides are a proven guide for both street and track use. However we do recommend our Moldstar90 guides for those that are going to be doing serious track duty and those looking for an "overkill guide" for the street/strip.
Feel free to give us a call
310-326-2399
or email us at
Parts@americanheritageperformance.com
for any additional information. We are always glad to answer any questions.
http://www.americanheritageperformance.com/
Last edited by American Heritage 3; 09-02-2016 at 08:34 PM. Reason: spelling/wording
