LS1 Dart head Issues All read
I posted this in your thread on Corvetteforum, but since a lot of guys here don't visit that site I will re-post here as well:
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I have some questions. Are your talking about the scratch on the retainer? This would indicate you are rotating the retainer, which in turn indicates valve float or loss of control of the spring.
These are not the valves, springs or retainers that come with the Dart heads, correct? As I remember, the valves were Ferea, a known heavy valve.
How did the rocker stand cause this, it is held in place by two things, rocker fastener preload and it is up against the machined stop of the head. Unless you are losing the fastener preload, the rocker stand cannot move and is actually supported better than the stock head because of the design of the rocker stand bosses that Dart used.
I am not sure how you can claim this to be a Dart problem, the only part of the head you are running is their casting as I remember from your earlier posts. If you compare the retainer you are running to Dart's, I think you might see they are shaped differently, and this may be a reason as well.
__________________________________________________ ____
I have some questions. Are your talking about the scratch on the retainer? This would indicate you are rotating the retainer, which in turn indicates valve float or loss of control of the spring.
These are not the valves, springs or retainers that come with the Dart heads, correct? As I remember, the valves were Ferea, a known heavy valve.
How did the rocker stand cause this, it is held in place by two things, rocker fastener preload and it is up against the machined stop of the head. Unless you are losing the fastener preload, the rocker stand cannot move and is actually supported better than the stock head because of the design of the rocker stand bosses that Dart used.
I am not sure how you can claim this to be a Dart problem, the only part of the head you are running is their casting as I remember from your earlier posts. If you compare the retainer you are running to Dart's, I think you might see they are shaped differently, and this may be a reason as well.
Teching In
Joined: May 2005
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I agree that with the 8 rocker bolts properly tourqed the rocker support will be clamped tight between the 8 rocker bodys and the head. I don't see how the lack of the tabs will cause the bolts to loosen. Once everything is tourqed the tabs no longer have a function as I see it.
Question regardless of head used.
If you have a scratch of that nature, are you better of replacing the retainer or is it OK to keep using it? Should you check valve springs too?
I ask because I took off my rockers last week to go with 7.300 PR's. I noticed 2 of the stock rocker arms had SERIOUS side to side play, so I sent them to Harland Sharp to get rebuilt. However on the 2 retainers where the rockers had play, I had scratches like in your photo. Thanks, not to hijack, I believe it's relevant.
If you have a scratch of that nature, are you better of replacing the retainer or is it OK to keep using it? Should you check valve springs too?
I ask because I took off my rockers last week to go with 7.300 PR's. I noticed 2 of the stock rocker arms had SERIOUS side to side play, so I sent them to Harland Sharp to get rebuilt. However on the 2 retainers where the rockers had play, I had scratches like in your photo. Thanks, not to hijack, I believe it's relevant.
Originally Posted by Viper
Question regardless of head used.
If you have a scratch of that nature, are you better of replacing the retainer or is it OK to keep using it? Should you check valve springs too?
If you have a scratch of that nature, are you better of replacing the retainer or is it OK to keep using it? Should you check valve springs too?
Originally Posted by 1bdindn
I agree that with the 8 rocker bolts properly tourqed the rocker support will be clamped tight between the 8 rocker bodys and the head. I don't see how the lack of the tabs will cause the bolts to loosen. Once everything is tourqed the tabs no longer have a function as I see it.
I may be wrong, but the high strength LPE rocker stands don't have tabs to start with. The shear strength on those tabs is minimal and their intial fit is sloppy, if they are needed to hold things in place then we would be seeing problems with the stock setup. I think this is another issue, not the tabs.
"Have you checked the clearance between the retainer and the rocker while rotating the
motor?"
Yes. I also assume if this was an issue with AFR heads you'd hear more about it right? If I recall with the cranes they tell you to make sure you have .060 clearance. My retainer scratched is from the rocker moving side to side.
motor?"
Yes. I also assume if this was an issue with AFR heads you'd hear more about it right? If I recall with the cranes they tell you to make sure you have .060 clearance. My retainer scratched is from the rocker moving side to side.
TECH Senior Member
Joined: Mar 2004
Posts: 14,620
Likes: 17
From: BFE
The scratches on the retainers are due to the retainer diameter being bigger than the rocker design allow.
With certain retainers, rockers have to be ground in that area to clear.
I agree with others that once the stands are bolted, they will not budge unless the bolts back out. Did you apply a slight amount of loctite to their extremities?
With certain retainers, rockers have to be ground in that area to clear.
I agree with others that once the stands are bolted, they will not budge unless the bolts back out. Did you apply a slight amount of loctite to their extremities?
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Originally Posted by PREDATOR-Z
With certain retainers, rockers have to be ground in that area to clear.
As posted by Viper, maybe the issue with the original poster is the bearings in his stock rockers and the resulting slop. Because the stockers don't use guide plates, they are dependent on the tolerances within the rollers to keep alignment.
Thread Starter
Staging Lane
Joined: Aug 2004
Posts: 51
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Originally Posted by vettenuts
Not to stray too far from the original post, but I don't like this method of correction because that part of the rocker is also one of the more highly stressed regions, and it is a tensile stress to boot.
As posted by Viper, maybe the issue with the original poster is the bearings in his stock rockers and the resulting slop. Because the stockers don't use guide plates, they are dependent on the tolerances within the rollers to keep alignment.
As posted by Viper, maybe the issue with the original poster is the bearings in his stock rockers and the resulting slop. Because the stockers don't use guide plates, they are dependent on the tolerances within the rollers to keep alignment.
Originally Posted by vettenuts
I have some questions. Are your talking about the scratch on the retainer? This would indicate you are rotating the retainer, which in turn indicates valve float or loss of control of the spring.
These are not the valves, springs or retainers that come with the Dart heads, correct? As I remember, the valves were Ferea, a known heavy valve.
How did the rocker stand cause this, it is held in place by two things, rocker fastener preload and it is up against the machined stop of the head. Unless you are losing the fastener preload, the rocker stand cannot move and is actually supported better than the stock head because of the design of the rocker stand bosses that Dart used.
I am not sure how you can claim this to be a Dart problem, the only part of the head you are running is their casting as I remember from your earlier posts. If you compare the retainer you are running to Dart's, I think you might see they are shaped differently, and this may be a reason as well.
These are not the valves, springs or retainers that come with the Dart heads, correct? As I remember, the valves were Ferea, a known heavy valve.
How did the rocker stand cause this, it is held in place by two things, rocker fastener preload and it is up against the machined stop of the head. Unless you are losing the fastener preload, the rocker stand cannot move and is actually supported better than the stock head because of the design of the rocker stand bosses that Dart used.
I am not sure how you can claim this to be a Dart problem, the only part of the head you are running is their casting as I remember from your earlier posts. If you compare the retainer you are running to Dart's, I think you might see they are shaped differently, and this may be a reason as well.
On a stock unit some tabs keep the guide aligned.(they have to be removed to bolt on dart heads)
If you look at the top picture you can see the rockers are angled.
the rocker guide moved up not down.
They were not when we set them up.
Yes we are using Ferea valves.
We set them up to dart specs.
We are also using titanium retainers.
Comp 918 springs.
The heads were purchased bare.
They have not been floating.
I know what that sounds like and that is not the case.
No high rpm passes have been done accept on the dyno.
No valve float was seen on the dyno.
Last edited by NOT-MEE; Mar 19, 2006 at 01:59 PM.
Thread Starter
Staging Lane
Joined: Aug 2004
Posts: 51
Likes: 0
Originally Posted by Viper
"Have you checked the clearance between the retainer and the rocker while rotating the
motor?"
Yes. I also assume if this was an issue with AFR heads you'd hear more about it right? If I recall with the cranes they tell you to make sure you have .060 clearance. My retainer scratched is from the rocker moving side to side.
motor?"
Yes. I also assume if this was an issue with AFR heads you'd hear more about it right? If I recall with the cranes they tell you to make sure you have .060 clearance. My retainer scratched is from the rocker moving side to side.
We are going to set the valvetrain up again first.
I posted here after waiting 2 days for dart to even try to call me back and they never did. I also called them 2x per day but the gentleman I need to talk to was away from his desk and they said he would call me as soon as he returns.
I really do not want to start all over and pull the heads.
The stop I was referring to is the boss for the valve cover bolt. It is milled along with the rocker bosses to form a stop for the rocker stand. Not sure how much Dart will help, since you have all aftermarket parts in their head.
Staging Lane
Joined: Apr 2003
Posts: 70
Likes: 0
From: Texas
You purchased these as bare heads correct??
Its not Darts problem, its the guy that set up the valve train.
Its like assembling an engine and not checking clearances, then blaming the crank manufacturer because it hits the piston skirt.
Its not Darts problem, its the guy that set up the valve train.
Its like assembling an engine and not checking clearances, then blaming the crank manufacturer because it hits the piston skirt.
Thread Starter
Staging Lane
Joined: Aug 2004
Posts: 51
Likes: 0
Originally Posted by Wire Dog
You purchased these as bare heads correct??
Its not Darts problem, its the guy that set up the valve train.
Its like assembling an engine and not checking clearances, then blaming the crank manufacturer because it hits the piston skirt.
Its not Darts problem, its the guy that set up the valve train.
Its like assembling an engine and not checking clearances, then blaming the crank manufacturer because it hits the piston skirt.
The heads were set up by a pro who buy's direct from dart.
The install was done by a forum vendor.
I have a issue and wasn't sure what part failed or even if one did. But if the tab's were not ground off there would of never been a problem.
Dart was called first they have not even addressed the issue.
Last edited by NOT-MEE; Mar 19, 2006 at 08:35 PM.
What was the installed valve stem height?
Did you check the wipe pattern to verify the geometry?
The rocker stands are meant to take compressive load only, the tabs won't hold any load and are not meant to by design. I really think you have a valve train geometry issue myself.
Did you check the wipe pattern to verify the geometry?
The rocker stands are meant to take compressive load only, the tabs won't hold any load and are not meant to by design. I really think you have a valve train geometry issue myself.
Thread Starter
Staging Lane
Joined: Aug 2004
Posts: 51
Likes: 0
Originally Posted by vettenuts
What was the installed valve stem height?
Did you check the wipe pattern to verify the geometry?
The rocker stands are meant to take compressive load only, the tabs won't hold any load and are not meant to by design. I really think you have a valve train geometry issue myself.
Did you check the wipe pattern to verify the geometry?
The rocker stands are meant to take compressive load only, the tabs won't hold any load and are not meant to by design. I really think you have a valve train geometry issue myself.
Thread Starter
Staging Lane
Joined: Aug 2004
Posts: 51
Likes: 0
Originally Posted by Wire Dog
Those tabs are thin cast aluminum, do you seriously think that is the problem??
Those tabs are just locaters to enable the build process.
I think you need to talk to your "pro"
Those tabs are just locaters to enable the build process.
I think you need to talk to your "pro"
And that might just be the problem.
TECH Senior Member
Joined: Mar 2004
Posts: 14,620
Likes: 17
From: BFE
As mentionned by Vettenuts, I think this is a geometry issue.
918's and retainers should clear the rocker and never hit, unless the valves are longer and rocker geometry was skewed.
BTW, the twisting of stock rockers happen on stock setups as well, they are not shafted so they can twist if they fall out of trq spec.
The stand pilots are not the issue here.
When you do a reinstall, do a wipe test, I believe you'll find that your wipe is closer to intake side on the valve tip and that you should have shimmed your stand.
Keep us posted.
918's and retainers should clear the rocker and never hit, unless the valves are longer and rocker geometry was skewed.
BTW, the twisting of stock rockers happen on stock setups as well, they are not shafted so they can twist if they fall out of trq spec.
The stand pilots are not the issue here.
When you do a reinstall, do a wipe test, I believe you'll find that your wipe is closer to intake side on the valve tip and that you should have shimmed your stand.
Keep us posted.
