Changing Valve Springs On The Engine


Changing Valve Springs On the Engine



Changing or removing valve springs on an assembled engine isn't difficult. However if a mistake is made it can result in a LOT of work (as in removing a head) to correct. There are also easy and not so easy ways to go about it. The following is what I believe to be the easiest way on a Chevy V8 and works well.

Many people think you need an air compressor and spark plug hole air fitting. Not true. In fact it's easier to just stuff a small rubber vacuum hose (3/16" O.D. or smaller), piece of small spark plug wire, or small rope into the cylinder with the piston at TDC on the compression stroke. It's easy to find Top Dead Center (TDC) with #1 and #6 cylinders by lining up the mark on the balancer with the zero mark on the timing tab. For the other cylinders you need to make marks at each 90 degree location on the balancer and follow the firing order.  To do that, measure the circumference of the balancer with a cloth tape measure and divide by four. Make a mark at each 90 degrees. Don't have a cloth tape? Use a piece of string, etc., or something that won't stretch, wrap it around the balancer, and mark both ends of the string at the mark on the balancer. Then take the string off, divide it into 4 equal parts, and mark it. Re-wrap it on the balancer and use those marks to mark the balancer at 90 degree locations.   As mentioned, the cylinder that springs are being changed on must have the piston at TDC on the compression stroke. That means both valves will be closed. Note that it's best to turn the engine by hand, which is much easier to do if all spark plugs are removed. Even easier if all rocker arms are loosened also. With the piston at TDC, stuff as much tubing or rope into the spark plug hole as possible. Be SURE the piston is at TDC. Use an on-engine valve spring compressor to compress the valve spring and retainer. The lower priced compressors are available from Jegs and other places for about $22. When you compress it, the valve will go down a little before contacting the tubing or rope. If it keeps going down without contacting anything, stop. The piston isn't at TDC and must be moved. With the spring compressed, use a magnet to pull the locks out. You can guess where the locks will go if you drop one. If the locks are stuck and the retainer won't break loose, place a 5/8" socket on the retainer and rap it with a hammer a couple times. Usually, that will unstick the locks. Unbolt the compressor from the rocker stud and remove the spring, retainer, etc. Reverse the procedure with the spring compressor to reinstall . DO NOT turn the engine at all with valve springs or retainers removed. The valve could fall down into the cylinder and the head must be removed to retrieve it