changing valve springs while the engines IN THE CAR

[grumpyvette]

now most shops will rotate the cylinder to TDC and install an adapter for an air hose and pump a steady 100-130psi into the cylinder to hold the valves closed, but theres frequently clearance problems with headers and the adapters or hose and since you need to wack the valve retainer with a plastic hammer at times to get them free.......
yeah, IVE use air pressure frequently, BUT IVE NEVER TRUSTED air pressure ....and HATE paying rental fees.....if you don,t have the adapters or compressor,ETC. Ive usually prefered the old method of manually turning the cylinder to bottom dead center and removing the spark plug, then inserting about 10 feet of 3/8" cotton rope into the cylinder(TIE A KNOT in the end to prevent it from falling ALL the way in) then spin the engine MANUALLY (NOT WITH THE STARTER) to as close to TDC,as the crank will spin. this compresses the rope into a wad that supports the valve physically preventing its movement, down into the cylinder, once the valve springs replaced , you rotate the cylinder to BDC and remove the rope, proceed to the next cylinder
BTW I vastly prefer these

http://store.summitracing.com/partdetail.asp?part=PRO%2D66784&N=%2D114082+115&autoview=sku
to these

http://store.summitracing.com/partdetail.asp?part=MAN%2D41830&N=%2D114082+115&autoview=sku
but if you use an air compressor youll NEED these
http://www.tavia.com/cat15.html

 

[motorman]

if you do the rope trick make sure you break loose the keys from the valve spring retainer with a sharp blow on a 9/16" deep socket over the keys in the retainer before you install the rope. if you do this after you do the rope trick you could bend a valve