Camshaft questions
Thread Starter
Instructor
Joined: Jan 2009
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From: Long Island New York
Camshaft questions
Hello all, I have a 1975 stingray with a SB 400, my question is, can I remove the camshaft out of this motor while the engine is still in the car? if so, does anyone have any tips or see problems? I am also going to change the timing chain so if anyone has any ideas as to how hard this is to do, please post. Many thanks...
Racer
Joined: Mar 2001
Posts: 272
Likes: 3
From: Marion Ia
I did mine a few months ago. It was a pita, but less work than pulling the engine. You will need to remove the hood and radiator at a minimum. I also removed the radiator support so I could stand in front of the the engine while I worked. You will need to drop the oil pan to remove the timing chain cover. Do not forget to pull the fuel pump, the rod rides on a cam lobe.
I did not have any major issues and if I had to replace it again I would leave it in the car.
It is a personal choice so I'm sure someone will give you the other side of the story.
I did not have any major issues and if I had to replace it again I would leave it in the car.
It is a personal choice so I'm sure someone will give you the other side of the story.
Thread Starter
Instructor
Joined: Jan 2009
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From: Long Island New York
Thanks Pete
Pete, did you change the camshaft bearings when you changed the cam? I have been told they do not usually wear that much, but I don't know how to change them. Is that something that can be done with the motor in the car, or is there any way to tell if they are worn?
Instructor
Joined: Aug 2009
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From: Demotte In
Hello
Well i think that it will be hard to degree and balance the cam to the crank shaft with the enigne in the car- You should degree the cam shaft so you get the best efficiency and ***** power out of the engine.
Just my thoughts- I did pull my engine and had it rebult top and bottom and clutch.
Best of luck
Ed
Well i think that it will be hard to degree and balance the cam to the crank shaft with the enigne in the car- You should degree the cam shaft so you get the best efficiency and ***** power out of the engine.
Just my thoughts- I did pull my engine and had it rebult top and bottom and clutch.
Best of luck
Ed
Thread Starter
Instructor
Joined: Jan 2009
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From: Long Island New York
Thanks Ed
Ed has a good point, I believe the cam in the car is stock right now, is it absolutely necessary to match the cam and crank? any thoughts? I was just going to buy a stock cam and lifter set and swap out what I have.
Le Mans Master
Joined: Jun 2008
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From: Rockledge FL
you wouldnt believe the number of people that on this forum alone that change their cams with the motor still in the car. a cam change is one of the first internal mods people do.
you balance the crank, balancer, and pistons together. the cam doesnt factor into it.
as far as degreeing the cam, dont you need adjustable timing gears to do that anyway?
you balance the crank, balancer, and pistons together. the cam doesnt factor into it.
as far as degreeing the cam, dont you need adjustable timing gears to do that anyway?
Melting Slicks
Joined: May 2007
Posts: 3,246
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From: Bay Area CA
Pete's 73 is right, that's the best way to do it. I recently did a full top end rebuild, with the engine in the car, including the cam. You just need to pull the hood and the radiator. The hood is a 5 min job (make alignment marks before you pull) with two or three people. The radiator is a giant PITA. listen to the others and pull the support. When GM built these cars, they attached everything to that support and dropped it into the car. There is literally no way to removed the shroud w/o cutting it, if the rad and support isn't removed first. Took me 3.5hrs to remove the rad, with a cut shroud, and i've been working on cars 25 years. other note, be sure to pinch off or plug the 3/8" feed line to the fuel pump, from the frame, or your gas tank will empty itself onto you garage floor.
Racer
Joined: Mar 2001
Posts: 272
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From: Marion Ia
I did not degree the cam, I am not running a full race engine and have never done this and have never had an issue. I am an old guy, learned to build engines in the 60's we did not have all the special tools back then, but seemed to be able to build a decent engine that would hold together. I'm not saying that it is not useful, but for most purposes this is over kill. I did not replace my cam bearings to do this you will probably need to pull the engine.
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Thread Starter
Instructor
Joined: Jan 2009
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From: Long Island New York
Thanks all!
wow thanks for all the info, since it was mentioned and I would not have thought it a problem, is there an easy way to get the radiator out of the car? Also, when I did the mains and rod bearings, I noticed that the timing chain has slack on one side, how much slack should be in a timing chain? If you move he chain from the middle of the gears, how much should I be able to move it? From what I remember, I have about a good half in or maybe more of play. If this is not supposed to be here, I will have to change the chain as well. Anyone know?
Le Mans Master
Joined: Jun 2004
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From: Seattle WA
St. Jude Donor '14
"balance the cam"? No such thing.
As for degreeing the cam, it's a good idea but certainly not required at this power level. Modern cams and gears don't show much variance these days. You do want to take extra care to ensure the cam is correctly installed.
You should definitely change the timing gears and chain - they're almost always well-stretched and it's an easy and cheap swap.
Typically liberal use of RTV on the bottom of the timing cover gasket and pan gasket is required to prevent leaks when the pan is dropped.
I haven't tried it, but I have to think it's virtually impossible to change the cam bearings in the car. There's nowhere for the old ones to go when you drive them out...and no easy way to get the tool in to drive in the new ones. Cam bearings do typically last a long time - and again, at this power level it's probably a reasonable risk to just reuse the existing bearings. I would take a look with a flashlight once the old cam is out just to be sure you're not showing copper.
As for degreeing the cam, it's a good idea but certainly not required at this power level. Modern cams and gears don't show much variance these days. You do want to take extra care to ensure the cam is correctly installed.
You should definitely change the timing gears and chain - they're almost always well-stretched and it's an easy and cheap swap.
Typically liberal use of RTV on the bottom of the timing cover gasket and pan gasket is required to prevent leaks when the pan is dropped.
I haven't tried it, but I have to think it's virtually impossible to change the cam bearings in the car. There's nowhere for the old ones to go when you drive them out...and no easy way to get the tool in to drive in the new ones. Cam bearings do typically last a long time - and again, at this power level it's probably a reasonable risk to just reuse the existing bearings. I would take a look with a flashlight once the old cam is out just to be sure you're not showing copper.
Burning Brakes
Joined: Aug 2005
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From: Europe, France
I would say you should be able to move the timing chain by 1/4 to 1/2" max. But If you replace camshaft, it's a good time to replace the timing chain and gears too. These are cheap parts, and it's a long job if you have to do it again...
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Thread Starter
Instructor
Joined: Jan 2009
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From: Long Island New York
Great everyone, now....
Now that I am psyched about doing this, how do you get the cam out? what special tools do I need, I remember taking off the harmonic balancer was hard (years ago) so have not done this in a while. I was thinking of changing the balancer and water pump too since I will be taking them off as well. I will probably boil out the radiator when I have it out as well. Any ideas? 
Racer
Joined: Mar 2001
Posts: 272
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From: Marion Ia
The balancer should be pulled with a special tool. It will be a gear puller that bolts to the holes instead of hooking to the outside. If you use a standard gear puller it will remove the outer ring and leave the center on the crank.
They make a tool to remove and install the cam, but I have always used threaded rod about 2 feet long screwed in to two of the cam gear bolt holes. I do not remember the size it's always in my tool box.
If you are not sure of what you are doing a buddy with knowledge would be a great help, if no friends are gear heads get a Haynes or Chiltons for C3 vettes, there should also be instructions with the cam.
You may want to search for setting lifters here on the forum, there are several methods that work. Pick the one you think you will be most comfortable with.
Make sure you are on top dead center with the #1 cylinder firing before you start pulling stuff apart it will save you a lot of headaches in re-assemblly. Also mark the position of your rotor and vacuum advance canister to make it easier to time when it goes back together.
They make a tool to remove and install the cam, but I have always used threaded rod about 2 feet long screwed in to two of the cam gear bolt holes. I do not remember the size it's always in my tool box.
If you are not sure of what you are doing a buddy with knowledge would be a great help, if no friends are gear heads get a Haynes or Chiltons for C3 vettes, there should also be instructions with the cam.
You may want to search for setting lifters here on the forum, there are several methods that work. Pick the one you think you will be most comfortable with.
Make sure you are on top dead center with the #1 cylinder firing before you start pulling stuff apart it will save you a lot of headaches in re-assemblly. Also mark the position of your rotor and vacuum advance canister to make it easier to time when it goes back together.
Le Mans Master
Joined: Jun 2008
Posts: 5,284
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From: Rockledge FL
you just have to make sure the cam gets pulled straight out. you have to support it all the way out and believe me its an wierd feeling the first time but if you let the cam fall while it is still halfway inside it can mess up the bearings.
Thread Starter
Instructor
Joined: Jan 2009
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From: Long Island New York
How do you support the cam on the way out?
Thanks for the info all, Baxsom, How do you support the cam all the way out? Please explain.. and as for the puller or threaded rod to take out the cam, do you mean like a gear puller of sorts?
Racer
Joined: Mar 2001
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From: Marion Ia
Le Mans Master
Joined: Jun 2008
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From: Rockledge FL
that tool is nice but a threaded rod works well too. the cam is long and heavy. there is no way you can hold it straight the farther it pulls out. so
all you have to do to support it is pull the cam out one section at a time and then support it with your other hand as close to the block as possible,
a helper to support while you pull makes it a little easier.
then when you reinstall, the easiets thing to do it only lube the lobes one section at a time
lube the first journal insert, coat the first set of lobes, lube the second journal, push the cam in until the second journal is inside the first set of bearings, and then repeat for each set of lobes and journals.
thats a lot easier than trying to balance the entire cam and stab it in straight.
all you have to do to support it is pull the cam out one section at a time and then support it with your other hand as close to the block as possible,
a helper to support while you pull makes it a little easier.
then when you reinstall, the easiets thing to do it only lube the lobes one section at a time
lube the first journal insert, coat the first set of lobes, lube the second journal, push the cam in until the second journal is inside the first set of bearings, and then repeat for each set of lobes and journals.
thats a lot easier than trying to balance the entire cam and stab it in straight.