Newb First Valvespring/Camshaft Install
01-07-2010, 08:34 PM
#23
Staging Lane
Join Date: Jul 2008
Location: Chicago, IL
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My advice after changing valve springs:
** USE THE TDC METHOD, NOT AIR **
Unless you are working on your car in a shop that has high regulated air pressure with huge air compressor tank reserves, the air method is simply not as reliable.
Consider that if you take a mallet and tap the tops of the valve stems to loosen the locks, they don't always come loose. When you start to depress the valvesprings for removal, if the locks aren't loose and it pushes the valve down with the spring, the gaping hole that is the exhaust or intake port will relieve all the pressure in the cylinder that is holding the valve shut.
Not that big of a deal if you have a huge air compressor tank and it can keep up with that kind of loss in pressure. What I experienced was that I used the SpeedInc tool to do both valves for one cylinder at the same time. I tapped them good and hard to loosen the locks, but when I cranked down the springs, both locks were still pulling the valve down with them.
By the time I tapped one valve loose, put the locks down on the bench and came back to tap the other valve loose, the open valves let out all the compressed air and my 15 gallon Craftsman compressor was down to 20psi.
Needless to say, that's not enough with a valve open to push it back up when it's freed. The valve fell into the head and LUCKILY the retainer caught the edge before it fell all the way in. I was able to rotate the crank and push the valve back up in.
The rest of the valvesprings I did using TDC. If the piston is at TDC, the valve will only fall into the cylinder maybe 1/2" at most - super easy.
** USE THE TDC METHOD, NOT AIR **
Unless you are working on your car in a shop that has high regulated air pressure with huge air compressor tank reserves, the air method is simply not as reliable.
Consider that if you take a mallet and tap the tops of the valve stems to loosen the locks, they don't always come loose. When you start to depress the valvesprings for removal, if the locks aren't loose and it pushes the valve down with the spring, the gaping hole that is the exhaust or intake port will relieve all the pressure in the cylinder that is holding the valve shut.
Not that big of a deal if you have a huge air compressor tank and it can keep up with that kind of loss in pressure. What I experienced was that I used the SpeedInc tool to do both valves for one cylinder at the same time. I tapped them good and hard to loosen the locks, but when I cranked down the springs, both locks were still pulling the valve down with them.
By the time I tapped one valve loose, put the locks down on the bench and came back to tap the other valve loose, the open valves let out all the compressed air and my 15 gallon Craftsman compressor was down to 20psi.
Needless to say, that's not enough with a valve open to push it back up when it's freed. The valve fell into the head and LUCKILY the retainer caught the edge before it fell all the way in. I was able to rotate the crank and push the valve back up in.
The rest of the valvesprings I did using TDC. If the piston is at TDC, the valve will only fall into the cylinder maybe 1/2" at most - super easy.
