Valve spring specs
Thread Starter
Burning Brakes
Joined: Aug 2006
Posts: 780
Likes: 0
From: New Port Richey Florida
Valve spring specs
I'm installing LT4 springs in my 86L and just wondering if any one that's done this mod has the specs handy...height, int/exh..coil bind etc. Thanks. 
Large Impressive Member
Joined: Jul 2003
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From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
Height is set at 1.78" when they're used on the LTx heads so that's what I'd shoot for. When they're used with the Hotcam and 1.6 rockers they're just about maxed out at .525" lift. In other words, they're close to their safety limit for bind. If your lift is that or less than that you should be fine. Does that answer everything?
Thread Starter
Burning Brakes
Joined: Aug 2006
Posts: 780
Likes: 0
From: New Port Richey Florida
Height is set at 1.78" when they're used on the LTx heads so that's what I'd shoot for. When they're used with the Hotcam and 1.6 rockers they're just about maxed out at .525" lift. In other words, they're close to their safety limit for bind. If your lift is that or less than that you should be fine. Does that answer everything?
Large Impressive Member
Joined: Jul 2003
Posts: 65,811
Likes: 71
From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
Team Owner
Joined: Jan 2003
Posts: 20,322
Likes: 248
From: Summerland B.C. Canada
Here's a cut and paste of a post I put in another thread. Food for thought 
You can't use any of the 128 head spring assembly parts with the LT4 spring. You will need the LT4 base+cap and new locks for piece of mind.
The exhaust rotators add height to the spring assembly so the head is machined to lower the exhaust valve spring seats. This causes a little grief when using the LT4 springs as you can't stack enough shims between the seat and spring to make up the difference of rotator.
The first year I used these springs, I put the shims under the seat. This works but I really never felt 100% comfortable with this because the shims do not fit snug to the valve guide and there is a chance that the shims could do a little walking around.
When I rebuilt my 128 heads 2 years later, I came up with a better mouse trap, I mean plan.
I took a tapered stone and enlarged the ID of LT4 base to slide over the L98 base. In between the 2 bases, I added my shims to get the correct installed height. There is now plenty of room to get all the shims in that you need to make up the exhaust rotator height. I did the same for the intakes, which only required one shim between bases.
Here are a few pics
You can't use any of the 128 head spring assembly parts with the LT4 spring. You will need the LT4 base+cap and new locks for piece of mind.
The exhaust rotators add height to the spring assembly so the head is machined to lower the exhaust valve spring seats. This causes a little grief when using the LT4 springs as you can't stack enough shims between the seat and spring to make up the difference of rotator.
The first year I used these springs, I put the shims under the seat. This works but I really never felt 100% comfortable with this because the shims do not fit snug to the valve guide and there is a chance that the shims could do a little walking around.
When I rebuilt my 128 heads 2 years later, I came up with a better mouse trap, I mean plan.
I took a tapered stone and enlarged the ID of LT4 base to slide over the L98 base. In between the 2 bases, I added my shims to get the correct installed height. There is now plenty of room to get all the shims in that you need to make up the exhaust rotator height. I did the same for the intakes, which only required one shim between bases.
Here are a few pics
Last edited by AGENT 86; Feb 26, 2007 at 08:57 AM.
Thread Starter
Burning Brakes
Joined: Aug 2006
Posts: 780
Likes: 0
From: New Port Richey Florida
Here's a cut and paste of a post I put in another thread. Food for thought
You can't use any of the 128 head spring assembly parts with the LT4 spring. You will need the LT4 base+cap and new locks for piece of mind.
The exhaust rotators add height to the spring assembly so the head is machined to lower the exhaust valve spring seats. This causes a little grief when using the LT4 springs as you can't stack enough shims between the seat and spring to make up the difference of rotator.
The first year I used these springs, I put the shims under the seat. This works but I really never felt 100% comfortable with this because the shims do not fit snug to the valve guide and there is a chance that the shims could do a little walking around.
When I rebuilt my 128 heads 2 years later, I came up with a better mouse trap, I mean plan.
I took a tapered stone and enlarged the ID of LT4 base to slide over the L98 base. In between the 2 bases, I added my shims to get the correct installed height. There is now plenty of room to get all the shims in that you need to make up the exhaust rotator height. I did the same for the intakes, which only required one shim between bases.
Here are a few pics
You can't use any of the 128 head spring assembly parts with the LT4 spring. You will need the LT4 base+cap and new locks for piece of mind.
The exhaust rotators add height to the spring assembly so the head is machined to lower the exhaust valve spring seats. This causes a little grief when using the LT4 springs as you can't stack enough shims between the seat and spring to make up the difference of rotator.
The first year I used these springs, I put the shims under the seat. This works but I really never felt 100% comfortable with this because the shims do not fit snug to the valve guide and there is a chance that the shims could do a little walking around.
When I rebuilt my 128 heads 2 years later, I came up with a better mouse trap, I mean plan.
I took a tapered stone and enlarged the ID of LT4 base to slide over the L98 base. In between the 2 bases, I added my shims to get the correct installed height. There is now plenty of room to get all the shims in that you need to make up the exhaust rotator height. I did the same for the intakes, which only required one shim between bases.
Here are a few pics
Large Impressive Member
Joined: Jul 2003
Posts: 65,811
Likes: 71
From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
Here's a cut and paste of a post I put in another thread. Food for thought
You can't use any of the 128 head spring assembly parts with the LT4 spring. You will need the LT4 base+cap and new locks for piece of mind.
The exhaust rotators add height to the spring assembly so the head is machined to lower the exhaust valve spring seats. This causes a little grief when using the LT4 springs as you can't stack enough shims between the seat and spring to make up the difference of rotator.
The first year I used these springs, I put the shims under the seat. This works but I really never felt 100% comfortable with this because the shims do not fit snug to the valve guide and there is a chance that the shims could do a little walking around.
When I rebuilt my 128 heads 2 years later, I came up with a better mouse trap, I mean plan.
I took a tapered stone and enlarged the ID of LT4 base to slide over the L98 base. In between the 2 bases, I added my shims to get the correct installed height. There is now plenty of room to get all the shims in that you need to make up the exhaust rotator height. I did the same for the intakes, which only required one shim between bases.
Here are a few pics
You can't use any of the 128 head spring assembly parts with the LT4 spring. You will need the LT4 base+cap and new locks for piece of mind.
The exhaust rotators add height to the spring assembly so the head is machined to lower the exhaust valve spring seats. This causes a little grief when using the LT4 springs as you can't stack enough shims between the seat and spring to make up the difference of rotator.
The first year I used these springs, I put the shims under the seat. This works but I really never felt 100% comfortable with this because the shims do not fit snug to the valve guide and there is a chance that the shims could do a little walking around.
When I rebuilt my 128 heads 2 years later, I came up with a better mouse trap, I mean plan.
I took a tapered stone and enlarged the ID of LT4 base to slide over the L98 base. In between the 2 bases, I added my shims to get the correct installed height. There is now plenty of room to get all the shims in that you need to make up the exhaust rotator height. I did the same for the intakes, which only required one shim between bases.
Here are a few pics
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Team Owner
Joined: Jan 2003
Posts: 20,322
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From: Summerland B.C. Canada
Drifting
Joined: Feb 2003
Posts: 1,614
Likes: 163
From: Davis CA
I'm in the process of gathering parts for this spring replacement and have a question.
I started down the LT4 path because the springs were so much less expensive and the alternative seem to be recommended here (about $40 for the set instead of $8 a piece-relying on memory here). Then I learned that I needed all the other items (caps, keepers, shims) and it isn't so cheap anymore.
So why is this a better alternative than just replacing springs or using something like the $75 Competition Cams' High Energy Valve Springs listed by one of our sponsors?
I started down the LT4 path because the springs were so much less expensive and the alternative seem to be recommended here (about $40 for the set instead of $8 a piece-relying on memory here). Then I learned that I needed all the other items (caps, keepers, shims) and it isn't so cheap anymore.
So why is this a better alternative than just replacing springs or using something like the $75 Competition Cams' High Energy Valve Springs listed by one of our sponsors?
Team Owner
Joined: Jan 2003
Posts: 20,322
Likes: 248
From: Summerland B.C. Canada
I'm in the process of gathering parts for this spring replacement and have a question.
I started down the LT4 path because the springs were so much less expensive and the alternative seem to be recommended here (about $40 for the set instead of $8 a piece-relying on memory here). Then I learned that I needed all the other items (caps, keepers, shims) and it isn't so cheap anymore.
So why is this a better alternative than just replacing springs or using something like the $75 Competition Cams' High Energy Valve Springs listed by one of our sponsors?
I started down the LT4 path because the springs were so much less expensive and the alternative seem to be recommended here (about $40 for the set instead of $8 a piece-relying on memory here). Then I learned that I needed all the other items (caps, keepers, shims) and it isn't so cheap anymore.
So why is this a better alternative than just replacing springs or using something like the $75 Competition Cams' High Energy Valve Springs listed by one of our sponsors?
Racer
Joined: Aug 2002
Posts: 386
Likes: 0
From: Lancaster Lancashire
The part# for the LT4 spring 'shim' (or base) is 10212809
LT4 Spring is #12551483 (each) or #12495494 for a set of 16 (cheapest option by a long way is to buy the set!)
LT4 retainers are 12495492 (set of 16)
Crane sell longer and shorter (by 0.050") installed height keepers that help a lot when trying to set up the installed height and avoids having to use shim stacks sometimes. Summit sells em.
Hope this is helpful.
LT4 Spring is #12551483 (each) or #12495494 for a set of 16 (cheapest option by a long way is to buy the set!)
LT4 retainers are 12495492 (set of 16)
Crane sell longer and shorter (by 0.050") installed height keepers that help a lot when trying to set up the installed height and avoids having to use shim stacks sometimes. Summit sells em.
Hope this is helpful.
