Is all this really needed to install a cam?
Thread Starter
Drifting
Joined: Oct 2007
Posts: 1,254
Likes: 5
From: Brown Summit North Carolina
Is all this really needed to install a cam?
I have started a project to install a original spec solid lifter cam back in to my 71 LT-1. The motor was rebuilt about 20 years ago , but only about 20K miles drove since then and the owner had a hyd. cam installed.
I have the Crane blueprinted cam / solid lifters / timing chain set but have not done the swap yet. The motor is out of the car while I clean and paint the firewall / fender skirts etc.
I was advised that it is needed for me to buy new valve springs. That is doable, the Crane set is about 100.00.
Where the problem starts is I am also being told I have to take the heads off and take them to a machine shop to get the seat pressue and heigth / lbs checked and set correctly.
Now that will lead to all kinds of other expenses that I am not prepared for. Vavle job etc.
What I do not get is why if I buy the correct single springs that the cam calls for , then why is the spring pressue not going to be correct?
Even if you do not take the heads off and install the springs your self , the testers are very expensive.
I want to do this right , but it's not a drag car.
Even at an LT-1 , I never go much over 5500 RPM and that is for short busrt.
Have I been given correct advice that I have to do all of the above or disaster will follow?
Thanks
David
I have the Crane blueprinted cam / solid lifters / timing chain set but have not done the swap yet. The motor is out of the car while I clean and paint the firewall / fender skirts etc.
I was advised that it is needed for me to buy new valve springs. That is doable, the Crane set is about 100.00.
Where the problem starts is I am also being told I have to take the heads off and take them to a machine shop to get the seat pressue and heigth / lbs checked and set correctly.
Now that will lead to all kinds of other expenses that I am not prepared for. Vavle job etc.
What I do not get is why if I buy the correct single springs that the cam calls for , then why is the spring pressue not going to be correct?
Even if you do not take the heads off and install the springs your self , the testers are very expensive.
I want to do this right , but it's not a drag car.
Even at an LT-1 , I never go much over 5500 RPM and that is for short busrt.
Have I been given correct advice that I have to do all of the above or disaster will follow?
Thanks
David
Race Director
Joined: Feb 1999
Posts: 16,978
Likes: 7
From: In Dreams There Is Truth Ohio
You want to match the springs to the cam, that's mandatory, the other things like new seats...take a compression check..write the numbers down, then squirt oil in the cyl and take another compression check, compare the numbers...if the initial check is bellow minimal requirement, and the same on the second check, then it will be advisable to get a valve grind, and your machine shop will be better qualified to tell you the condition of the seats, whether you have hard seats or not. If the compression numbers equal or exceed minimum, then the only question what about the seats...at this point...install the cam and run and forget about the seats.
Le Mans Master
Joined: Aug 2000
Posts: 6,362
Likes: 7
From: Brazos TX
Cruise-In IV Veteran
Cruise-In V Veteran
You don't have to do all of that but it is advisable to get the matched springs for the cam. You can check installed height with the heads on the engine. Just use a set of calipers or a good steel scale that measures down to .025" similar to this...
Just check the cam card and springs for the required installed height and measure each valve. Use the appropriate thickness shims to get as near as you can to the installed height called for. That's all that is needed. Comp Cams has a good tutorial on checking installed height on there web site.
Remember, rap the spring retainers a few times with a hammer before you try to compress the spring (don't hit the top of the valve). That will break the keepers loose and make it easier to disassemble once the spring is compressed.
Just check the cam card and springs for the required installed height and measure each valve. Use the appropriate thickness shims to get as near as you can to the installed height called for. That's all that is needed. Comp Cams has a good tutorial on checking installed height on there web site.
Remember, rap the spring retainers a few times with a hammer before you try to compress the spring (don't hit the top of the valve). That will break the keepers loose and make it easier to disassemble once the spring is compressed.
Drifting
Joined: Aug 2008
Posts: 1,381
Likes: 11
If the only thing changed 20 years ago was the cam, you can just change the cam. The factory springs were made to run with the solid lifter cam. Some will tell you to change them just because they are 37 years old - but this can be your choice. If the miles are low and the car only sees a few miles a year, go ahead and run the old springs. Personally, I would pop for a set of Crower springs and change them along with the seals while the engine is out. If you can change a cam, you can change valve springs!
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
Change the springs. Sitting for periods of time with only a few springs compressed will damage them qand this engine has done that a lot. When you store an engine for very long you should back the rockers off to relieve the tension epecially heavy springs. 
Crowers are good springs and change the seals. 20+ year old seals are done.
Crowers are good springs and change the seals. 20+ year old seals are done.
Race Director
Joined: Feb 1999
Posts: 16,978
Likes: 7
From: In Dreams There Is Truth Ohio
Maybe...a hydraulic cam replaced the solid lifter cam and common sense tells me that the springs were changed with the cam, not to mention the age of the springs. At worse, if the installed springs are factory installed, then they are how old?
Le Mans Master
Joined: Apr 2006
Posts: 5,403
Likes: 95
I have started a project to install a original spec solid lifter cam back in to my 71 LT-1. The motor was rebuilt about 20 years ago , but only about 20K miles drove since then and the owner had a hyd. cam installed.
I have the Crane blueprinted cam / solid lifters / timing chain set but have not done the swap yet. The motor is out of the car while I clean and paint the firewall / fender skirts etc.
I was advised that it is needed for me to buy new valve springs. That is doable, the Crane set is about 100.00.
Where the problem starts is I am also being told I have to take the heads off and take them to a machine shop to get the seat pressue and heigth / lbs checked and set correctly.
Now that will lead to all kinds of other expenses that I am not prepared for. Vavle job etc.
What I do not get is why if I buy the correct single springs that the cam calls for , then why is the spring pressue not going to be correct?
Even if you do not take the heads off and install the springs your self , the testers are very expensive.
I want to do this right , but it's not a drag car.
Even at an LT-1 , I never go much over 5500 RPM and that is for short busrt.
Have I been given correct advice that I have to do all of the above or disaster will follow?
Thanks
David
I have the Crane blueprinted cam / solid lifters / timing chain set but have not done the swap yet. The motor is out of the car while I clean and paint the firewall / fender skirts etc.
I was advised that it is needed for me to buy new valve springs. That is doable, the Crane set is about 100.00.
Where the problem starts is I am also being told I have to take the heads off and take them to a machine shop to get the seat pressue and heigth / lbs checked and set correctly.
Now that will lead to all kinds of other expenses that I am not prepared for. Vavle job etc.
What I do not get is why if I buy the correct single springs that the cam calls for , then why is the spring pressue not going to be correct?
Even if you do not take the heads off and install the springs your self , the testers are very expensive.
I want to do this right , but it's not a drag car.
Even at an LT-1 , I never go much over 5500 RPM and that is for short busrt.
Have I been given correct advice that I have to do all of the above or disaster will follow?
Thanks
David
How much lift you going to keep stock 1.5 ratio rockers ?
Instructor
Joined: Nov 2008
Posts: 106
Likes: 1
Change the springs. Sitting for periods of time with only a few springs compressed will damage them qand this engine has done that a lot. When you store an engine for very long you should back the rockers off to relieve the tension epecially heavy springs. Crowers are good springs and change the seals. 20+ year old seals are done.
Crowers are good springs and change the seals. 20+ year old seals are done. All of this is easily done with the motor out on a stand, instead of while you are pulling the motor back wishing you had done it the first time. Go on and do all those things to the motor now, before you even think about sitting it back in the car. The rebuild I just finished on our car, just a 350, it is new or been checked out from the motor mounts up from people, I have faith in, knew what they were doing. It cost us a lot more than we originally planned to spend, but I am not regretting not doing it up right the first time.Have a Great day,
Ray/aka/Pa
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Thread Starter
Drifting
Joined: Oct 2007
Posts: 1,254
Likes: 5
From: Brown Summit North Carolina
Thread Starter
Drifting
Joined: Oct 2007
Posts: 1,254
Likes: 5
From: Brown Summit North Carolina
All of this is easily done with the motor out on a stand, instead of while you are pulling the motor back wishing you had done it the first time. Go on and do all those things to the motor now, before you even think about sitting it back in the car. The rebuild I just finished on our car, just a 350, it is new or been checked out from the motor mounts up from people, I have faith in, knew what they were doing. It cost us a lot more than we originally planned to spend, but I am not regretting not doing it up right the first time.Have a Great day,
Ray/aka/Pa
But are you saying remove the heads and take to a machine shop?
Or install at the house and check height and shim as needed?
Thanks
David
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
You can just change the springs, and as noted a valve spring height mic is pretty cheap.
I'd be more worried about the guides than anything; my suggestion is just to do some simple checks while you're changing the springs and if you don't see anything, then don't worry about it. There should be NO lateral movement of the valve when you pull it out an inch or so...if there is, then you'll need to get guides and the associated valve job.
In my experience, on older engines it's very common to see failures after this kind of top because the owner loves the new power and starts getting a heavy right foot. Those parts that were doing OK are now suddenly seeing full throttle runs and pulls to the redline...and stuff breaks.
Make SURE you check the condition of the heads and the valvetrain geometry very carefully - this is the most common cause of failure on a cam swap/top.
I'd be more worried about the guides than anything; my suggestion is just to do some simple checks while you're changing the springs and if you don't see anything, then don't worry about it. There should be NO lateral movement of the valve when you pull it out an inch or so...if there is, then you'll need to get guides and the associated valve job.
In my experience, on older engines it's very common to see failures after this kind of top because the owner loves the new power and starts getting a heavy right foot. Those parts that were doing OK are now suddenly seeing full throttle runs and pulls to the redline...and stuff breaks.
Make SURE you check the condition of the heads and the valvetrain geometry very carefully - this is the most common cause of failure on a cam swap/top.
Burning Brakes
Joined: Jan 2007
Posts: 1,057
Likes: 4
From: Concord Calif
I have started a project to install a original spec solid lifter cam back in to my 71 LT-1. The motor was rebuilt about 20 years ago , but only about 20K miles drove since then and the owner had a hyd. cam installed.
I have the Crane blueprinted cam / solid lifters / timing chain set but have not done the swap yet. The motor is out of the car while I clean and paint the firewall / fender skirts etc.
I was advised that it is needed for me to buy new valve springs. That is doable, the Crane set is about 100.00.
Where the problem starts is I am also being told I have to take the heads off and take them to a machine shop to get the seat pressue and heigth / lbs checked and set correctly.
Now that will lead to all kinds of other expenses that I am not prepared for. Vavle job etc.
What I do not get is why if I buy the correct single springs that the cam calls for , then why is the spring pressue not going to be correct?
Even if you do not take the heads off and install the springs your self , the testers are very expensive.
I want to do this right , but it's not a drag car.
Even at an LT-1 , I never go much over 5500 RPM and that is for short busrt.
Have I been given correct advice that I have to do all of the above or disaster will follow?
Thanks
David
I have the Crane blueprinted cam / solid lifters / timing chain set but have not done the swap yet. The motor is out of the car while I clean and paint the firewall / fender skirts etc.
I was advised that it is needed for me to buy new valve springs. That is doable, the Crane set is about 100.00.
Where the problem starts is I am also being told I have to take the heads off and take them to a machine shop to get the seat pressue and heigth / lbs checked and set correctly.
Now that will lead to all kinds of other expenses that I am not prepared for. Vavle job etc.
What I do not get is why if I buy the correct single springs that the cam calls for , then why is the spring pressue not going to be correct?
Even if you do not take the heads off and install the springs your self , the testers are very expensive.
I want to do this right , but it's not a drag car.
Even at an LT-1 , I never go much over 5500 RPM and that is for short busrt.
Have I been given correct advice that I have to do all of the above or disaster will follow?
Thanks
David
Well there will be all kinds of advise on this, but check lift numbers on the cam that is in the engine now. If they are the same or close usually within .010 to ,015 of the new cam then the springs are just fine you have as long as they are in good shape. Basicly all a spring needs to accomadate is the lift of the cam as I said above same lift old cam close lift on new cam then run it as is.
Le Mans Master
Joined: Apr 2006
Posts: 5,403
Likes: 95
pressure 330 at .485 340 at .500 lift coil bind at 1.150. they have a real good high spring rate 432. You have to keep 1.5 ratio with these springs if you use 1.6 on the exhaust you would be to close to coil bind.
The viton oil seals the type that just push over the stock guide by hand are what you need.
With all your very low lift low pressure stuff you don't really have to have things perfect, lets put it this way this is the way the factory done it if your engine were brand new never been rebuilt you pulled it apart you would not find any shims under the the valve springs. They ran fine factory warrantied them for 36 months,50,000 miles back then.
no machining of valve guide required
Viton oil seals for 11/32 valves part # S5325
www.competitionproducts.com
Last edited by Little Mouse; Dec 30, 2008 at 01:48 PM.
Thread Starter
Drifting
Joined: Oct 2007
Posts: 1,254
Likes: 5
From: Brown Summit North Carolina
Just get the Crane Z/28 springs 99848-16, $69.95 stock 1.255 dia. stock intalled height 1.70 they hava a seat pressure of 114 open
pressure 330 at .485 340 at .500 lift coil bind at 1.150. they have a real good high spring rate 432. You have to keep 1.5 ratio with these springs if you tried 1.6 on the exhaust you would be to close to coil bind.
The viton oil seals the type that just push over the stock guide by hand are what you need.
With all your very low lift low pressure stuff you don't really have to have things perfect, lets put it this way this is the way the factory done it if your engine were brand new never been rebuilt you pulled it apart you would not find any shims under the the valve springs. They ran fine factory warrantied them for 36 months,50,000 miles back then.
pressure 330 at .485 340 at .500 lift coil bind at 1.150. they have a real good high spring rate 432. You have to keep 1.5 ratio with these springs if you tried 1.6 on the exhaust you would be to close to coil bind.
The viton oil seals the type that just push over the stock guide by hand are what you need.
With all your very low lift low pressure stuff you don't really have to have things perfect, lets put it this way this is the way the factory done it if your engine were brand new never been rebuilt you pulled it apart you would not find any shims under the the valve springs. They ran fine factory warrantied them for 36 months,50,000 miles back then.
Thanks Little Mouse
I am starting to feel a little better on the advice I am getting.
I was ordering the Crane 11308-1 set of springs and retainers. This set has the 99848 springs in them.
Thanks
David
Le Mans Master
Joined: Apr 2006
Posts: 5,403
Likes: 95
Those springs have a very good amount of rate 432 there going to control those valves when you do decide 5500 rpm is just not enough.
Its funny I have a 2006 Crane catalog but it does not show the Lt1 cam in it , nor could I find it on cranes web site by using BLUEPRINT cams how did you find it. ?
Last edited by Little Mouse; Dec 30, 2008 at 02:17 PM.
Thread Starter
Drifting
Joined: Oct 2007
Posts: 1,254
Likes: 5
From: Brown Summit North Carolina
well I fiqured the LT1 blueprint cam would show to use the same Z/28 springs. The factory used the same springs on the Z/28 and LT1 yrs ago.
Those springs have a very good amount of rate 432 there going to control those valves when you do decide 5500 rpm is just not enough.
Its funny I have a 2006 Crane catalog but it does not show the Lt1 cam in it , nor could I find it on cranes web site by using BLUEPRINT cams how did you find it. ?
Those springs have a very good amount of rate 432 there going to control those valves when you do decide 5500 rpm is just not enough.
Its funny I have a 2006 Crane catalog but it does not show the Lt1 cam in it , nor could I find it on cranes web site by using BLUEPRINT cams how did you find it. ?
I called Crane over a year ago and told them what I was looking for and they gave me the part #. I actually bought the cam back then.
I have just never got around to doing the swap until now.
My car looks and runs great. It has been a tough desision to take apart a running motor to install the cam.
But the car is mostly original so I want the right cam.
Next big expense will be the A.I.R system. But that will have to wait until I win the lottery.
As for the cam. If you plug it in on their web site it will come up.
here is a link
http://www.cranecams.com/index.php?s...51&lvl=2&prt=5
Thanks
Thread Starter
Drifting
Joined: Oct 2007
Posts: 1,254
Likes: 5
From: Brown Summit North Carolina
Well there is no turning back now. I removed the old cam tonight as well as the rocker arms.
The parts all looked good no ugly surprises on condition of parts.
The lifters had Crane part # 99277 on them.
The cam has a # that is hard to see. the # is ???96962. Can not make out the 1st. 3 digits. It did not match up on the Crane site , I will call them tomorrow and see if they can ID.
But just by eye site I can see that the lobes on the new solid lift cam are more rounded than the HYD cam.
I assume that mears more duration???
Thanks to all for the assistance.
David
The parts all looked good no ugly surprises on condition of parts.
The lifters had Crane part # 99277 on them.
The cam has a # that is hard to see. the # is ???96962. Can not make out the 1st. 3 digits. It did not match up on the Crane site , I will call them tomorrow and see if they can ID.
But just by eye site I can see that the lobes on the new solid lift cam are more rounded than the HYD cam.
I assume that mears more duration???
Thanks to all for the assistance.
David
Last edited by dmayhew; Dec 30, 2008 at 09:03 PM.
Burning Brakes
Joined: Dec 2007
Posts: 952
Likes: 0
Well there will be all kinds of advise on this, but check lift numbers on the cam that is in the engine now. If they are the same or close usually within .010 to ,015 of the new cam then the springs are just fine you have as long as they are in good shape. Basicly all a spring needs to accomadate is the lift of the cam as I said above same lift old cam close lift on new cam then run it as is.
