Why do the Crane 832's need to be shimmed
TECH Resident
Joined: Dec 2004
Posts: 845
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From: K-W, Ontario
0.030" is a nasty thick shim.
I don't believe it's good practice to install such a heavy shim when it cuts
into bind clearanace and spring harmonics.
If one, or two valves are out by 0.030", you might want to shoot the tech
that did the valve job.
If all of the valves need that much shimming, you would be better off to change the
install height, and cross reference a spring with similar open height pressure.
Of course, this is my opinion.
I don't believe it's good practice to install such a heavy shim when it cuts
into bind clearanace and spring harmonics.
If one, or two valves are out by 0.030", you might want to shoot the tech
that did the valve job.
If all of the valves need that much shimming, you would be better off to change the
install height, and cross reference a spring with similar open height pressure.
Of course, this is my opinion.
Last edited by Adrenaline_Z; May 29, 2005 at 02:26 PM.
On The Tree
Joined: Apr 2004
Posts: 119
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From: Quiet Place in the Country, FL
When I installed my Crane '832's, the Crane spring seat locator caused my installed height to be 1.760 and my seat pressure was 125#. The locator acts as a shim so you really don't need to go looking for shims. The locator part number is 144460-16 and I had to use 2001 valve guide seals with the locator. My truck is an 03 Tahoe with a 5.3.
On The Tree
Joined: Apr 2004
Posts: 119
Likes: 0
From: Quiet Place in the Country, FL
Originally Posted by Adrenaline_Z
0.030" is a nasty thick shim.
I don't believe it's good practice to install such a heavy shim when it cuts
into bind clearanace and spring harmonics.
If one, or two valves are out by 0.030", you might want to shoot the tech
that did the valve job.
If all of the valves need that much shimming, you would be better off to change the
install height and cross reference a spring with similar open height pressure.
Of course, this is my opinion.
I don't believe it's good practice to install such a heavy shim when it cuts
into bind clearanace and spring harmonics.
If one, or two valves are out by 0.030", you might want to shoot the tech
that did the valve job.
If all of the valves need that much shimming, you would be better off to change the
install height and cross reference a spring with similar open height pressure.
Of course, this is my opinion.
On The Tree
Joined: Apr 2004
Posts: 119
Likes: 0
From: Quiet Place in the Country, FL
Originally Posted by Adrenaline_Z
0.030" is a nasty thick shim.
I don't believe it's good practice to install such a heavy shim when it cuts
into bind clearanace and spring harmonics.
If one, or two valves are out by 0.030", you might want to shoot the tech
that did the valve job.
If all of the valves need that much shimming, you would be better off to change the
install height and cross reference a spring with similar open height pressure.
Of course, this is my opinion.
I don't believe it's good practice to install such a heavy shim when it cuts
into bind clearanace and spring harmonics.
If one, or two valves are out by 0.030", you might want to shoot the tech
that did the valve job.
If all of the valves need that much shimming, you would be better off to change the
install height and cross reference a spring with similar open height pressure.
Of course, this is my opinion.
TECH Resident
Joined: Dec 2004
Posts: 845
Likes: 0
From: K-W, Ontario
I'd like to read that study.
How can a spring that is slightly compressed have the same harmonics as
a spring sitting at full install height?
The dynamics are already different from the start.
How can a spring that is slightly compressed have the same harmonics as
a spring sitting at full install height?
The dynamics are already different from the start.
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Verdad Gallardo On The Tree
Joined: Apr 2004
Posts: 119
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From: Quiet Place in the Country, FL
Originally Posted by Adrenaline_Z
I'd like to read that study.
How can a spring that is slightly compressed have the same harmonics as
a spring sitting at full install height?
The dynamics are already different from the start.
How can a spring that is slightly compressed have the same harmonics as
a spring sitting at full install height?
The dynamics are already different from the start.
On The Tree
Joined: Apr 2004
Posts: 119
Likes: 0
From: Quiet Place in the Country, FL
Originally Posted by Adrenaline_Z
I'd like to read that study.
How can a spring that is slightly compressed have the same harmonics as
a spring sitting at full install height?
The dynamics are already different from the start.
How can a spring that is slightly compressed have the same harmonics as
a spring sitting at full install height?
The dynamics are already different from the start.
11 Second Club
Joined: Nov 2001
Posts: 1,320
Likes: 0
From: NE PA
Originally Posted by QuietTahoe
Where are you getting your info? Standard shims come in .060, .030 and sometimes .015 for trimming pressures.
The shim set that Comp Cams sells comes with 16 shims each (48 total) in .015", .030", and .060" thicknesses. These are the same standard thicknesses that have been used forever.
http://store.summitracing.com/partde...=KeywordSearch
TECH Resident
Joined: Dec 2004
Posts: 845
Likes: 0
From: K-W, Ontario
Take a spring that has a rate of 350#/in and the installed height is 1.800 and the seat pressure is 110#. If you put a .030 shim under the spring the effective installed height changes to 1.770 and the seat pressure increases 10.5#(.030in x 350 #/in =10.5# of force...) but the rate doesn't change at all, it still is 350#/in. If you don't understand this basic concept of coil springs, STEP AWAY FROM THE WRENCH!!
rarefaction at open height? Wouldn't you be a little worried cutting into
the clearance by 0.030" @ 6200 RPM?
The "nasty thick" .030" shim has been in common use for decades and so has the, God Forbid, .060" shim.
of the valve work or spring.
I understand the need to shim springs to get the correct pressure. Don't
misread what I'm stating. I have shims under my springs as well.
What you both are misunderstanding is...0.030" correction for a spring is out
of spec.
If all of the springs are installed at 1.8" and ONE, or TWO springs need a 0.030"
shim to correct the pressure @ 1.770" ...don't you think those springs need to be
swapped out?
That's not the part that bugs me, it's the fact that coil bind comes sooner
and the clearance window is totally off.
OR
If all of the springs are isntalled at 1.8", and ONE, or TWO need 0.030" + shims
to correct a crappy valve job, you'd be happy with that? Sure the springs
are all at 1.8" again, but I'd be handing the heads back to the tech and
get some new valve seats installed at his expense.
Unless you like variance in combustion chamber volume
Last edited by Adrenaline_Z; May 28, 2005 at 10:30 AM.
On The Tree
Joined: Apr 2004
Posts: 119
Likes: 0
From: Quiet Place in the Country, FL
Originally Posted by Adrenaline_Z
What does that have to do with harmonics? OK, so the rate to close the spring doesn't change. But what about the clearance to allow for
rarefaction at open height? Wouldn't you be a little worried cutting into
the clearance by 0.030" @ 6200 RPM?
If I'm using a 0.030 to 0.060" shim in my valve train, I question the quality
of the valve work or spring.
I understand the need to shim springs to get the correct pressure. Don't
misread what I'm stating. I have shims under my springs as well.
What you both are misunderstanding is...0.030" correction for a spring is out
of spec.
If all of the springs are installed at 1.8" and ONE, or TWO springs need a 0.030"
shim to correct the pressure @ 1.770" ...don't you think those springs need to be
swapped out?
That's not the part that bugs me, it's the fact that coil bind comes sooner
and the clearance window is totally off.
OR
If all of the springs are isntalled at 1.8", and ONE, or TWO need 0.030" + shims
to correct a crappy valve job, you'd be happy with that? Sure the springs
are all at 1.8" again, but I'd be handing the heads back to the tech and
get some new valve seats installed at his expense.
Unless you like variance in combustion chamber volume
rarefaction at open height? Wouldn't you be a little worried cutting into
the clearance by 0.030" @ 6200 RPM?
If I'm using a 0.030 to 0.060" shim in my valve train, I question the quality
of the valve work or spring.
I understand the need to shim springs to get the correct pressure. Don't
misread what I'm stating. I have shims under my springs as well.
What you both are misunderstanding is...0.030" correction for a spring is out
of spec.
If all of the springs are installed at 1.8" and ONE, or TWO springs need a 0.030"
shim to correct the pressure @ 1.770" ...don't you think those springs need to be
swapped out?
That's not the part that bugs me, it's the fact that coil bind comes sooner
and the clearance window is totally off.
OR
If all of the springs are isntalled at 1.8", and ONE, or TWO need 0.030" + shims
to correct a crappy valve job, you'd be happy with that? Sure the springs
are all at 1.8" again, but I'd be handing the heads back to the tech and
get some new valve seats installed at his expense.
Unless you like variance in combustion chamber volume
TECH Resident
Joined: Dec 2004
Posts: 845
Likes: 0
From: K-W, Ontario
I think you need to read your books again, or maybe get into working on
cylinder heads instead of trying to apply what you read...to something
you don't quite understand.
Everything in my reply is solid.
If you think adding a 0.030" shim is normal, I question your understanding
of machine work and tolerances. Either that, or the spring selection is way
off.
cylinder heads instead of trying to apply what you read...to something
you don't quite understand.
Everything in my reply is solid.
If you think adding a 0.030" shim is normal, I question your understanding
of machine work and tolerances. Either that, or the spring selection is way
off.
Last edited by Adrenaline_Z; May 29, 2005 at 03:06 AM.
TECH Resident
Joined: Dec 2004
Posts: 845
Likes: 0
From: K-W, Ontario
We're not talking about install height for shims, but rather, shimming for
pressure (at least I am).
In all fairness, I re-read the post from top to bottom, and I see that the
discussion refers to another revision of spring on the lower half of the first
page.
What started out as an opinion (Post #24), has turned into a battle.
If you need to shim to get the install height - fine.
If you need to shim to get pressures:
a. Do you have the best suited spring?
b. Are you sacrificing clearance, or spring characteristics?
My position to clarify once again:
A 0.030" correction shim is out of spec IMO. A spring that sits at 1.770" with
125 lbs. seat pressure has a different spring rate than a spring that sits at
1.800" with 125 lbs. seat pressure.
The harmonics throughout each spring in the above scenario will be different.
I would not want a few of my springs shimmed at 0.030" or more, where the
others are at full install height.
As for shimming all springs for seat pressure, I would much rather install an
offset lock, or retainer ... or select another spring before I cut my open
height and clearance by 0.030"
Again, this is my opinion. It's an alternative to setting up a valve train
for correct pressures while leaving enough clearance for high RPM use.
pressure (at least I am).
In all fairness, I re-read the post from top to bottom, and I see that the
discussion refers to another revision of spring on the lower half of the first
page.
What started out as an opinion (Post #24), has turned into a battle.
If you need to shim to get the install height - fine.
If you need to shim to get pressures:
a. Do you have the best suited spring?
b. Are you sacrificing clearance, or spring characteristics?
My position to clarify once again:
A 0.030" correction shim is out of spec IMO. A spring that sits at 1.770" with
125 lbs. seat pressure has a different spring rate than a spring that sits at
1.800" with 125 lbs. seat pressure.
The harmonics throughout each spring in the above scenario will be different.
I would not want a few of my springs shimmed at 0.030" or more, where the
others are at full install height.
As for shimming all springs for seat pressure, I would much rather install an
offset lock, or retainer ... or select another spring before I cut my open
height and clearance by 0.030"
Again, this is my opinion. It's an alternative to setting up a valve train
for correct pressures while leaving enough clearance for high RPM use.
On The Tree
iTrader: (3)
Joined: Nov 2004
Posts: 178
Likes: 0
From: Park Ridge, IL (Borders Chicago)
Originally Posted by Adrenaline_Z
We're not talking about install height for shims, but rather, shimming for pressure (at least I am).
In all fairness, I re-read the post from top to bottom, and I see that the
discussion refers to another revision of spring on the lower half of the first
page.
What started out as an opinion (Post #24), has turned into a battle.
If you need to shim to get the install height - fine.
If you need to shim to get pressures:
a. Do you have the best suited spring?
b. Are you sacrificing clearance, or spring characteristics?
My position to clarify once again:
A 0.030" correction shim is out of spec IMO. A spring that sits at 1.770" with
125 lbs. seat pressure has a different spring rate than a spring that sits at
1.800" with 125 lbs. seat pressure.
The harmonics throughout each spring in the above scenario will be different.
I would not want a few of my springs shimmed at 0.030" or more, where the
others are at full install height.
As for shimming all springs for seat pressure, I would much rather install an
offset lock, or retainer ... or select another spring before I cut my open
height and clearance by 0.030"
Again, this is my opinion. It's an alternative to setting up a valve train
for correct pressures while leaving enough clearance for high RPM use.
In all fairness, I re-read the post from top to bottom, and I see that the
discussion refers to another revision of spring on the lower half of the first
page.
What started out as an opinion (Post #24), has turned into a battle.
If you need to shim to get the install height - fine.
If you need to shim to get pressures:
a. Do you have the best suited spring?
b. Are you sacrificing clearance, or spring characteristics?
My position to clarify once again:
A 0.030" correction shim is out of spec IMO. A spring that sits at 1.770" with
125 lbs. seat pressure has a different spring rate than a spring that sits at
1.800" with 125 lbs. seat pressure.
The harmonics throughout each spring in the above scenario will be different.
I would not want a few of my springs shimmed at 0.030" or more, where the
others are at full install height.
As for shimming all springs for seat pressure, I would much rather install an
offset lock, or retainer ... or select another spring before I cut my open
height and clearance by 0.030"
Again, this is my opinion. It's an alternative to setting up a valve train
for correct pressures while leaving enough clearance for high RPM use.
TECH Resident
Joined: Dec 2004
Posts: 845
Likes: 0
From: K-W, Ontario
the whole point of shimming a valvespring is to obtain the correct pressure.
then...not one size fits all with shimming?
I would think shimming is to balance the entire train pressures.
In any case...to each their own.
On The Tree
iTrader: (3)
Joined: Nov 2004
Posts: 178
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From: Park Ridge, IL (Borders Chicago)
Originally Posted by Adrenaline_Z
You think so? I guess that's why they have hundreds of different springs
then...not one size fits all with shimming?
I would think shimming is to balance the entire train pressures.
In any case...to each their own.
then...not one size fits all with shimming?
I would think shimming is to balance the entire train pressures.
In any case...to each their own.
Maybe you can point me towards this magical mountain of springs.
TECH Resident
Joined: Dec 2004
Posts: 845
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From: K-W, Ontario
I typed in "LS1 valve spring" in Google and came up with over 11,800 hits.
I'm sure there's a few different MFG's and spring types to choose from.
Even if those aren't enough, you can always machine the heads to accept
a wider range of spring.
I'm sure there's a few different MFG's and spring types to choose from.
Even if those aren't enough, you can always machine the heads to accept
a wider range of spring.