Review on Spring Compressor Automotive Compress Release by Rick Rogers

The idea here is correct, but if you have an older (eg 1949) flathead V-8 engine it will not fit. The lower fork, which can be adjusted to accommodate different sized valve spring retainers, just isn't strong enough to hold it without uncoiling outward after a few times. Even when the width adjustment screw is adjusted, it actually starts to flex the base legs attached to the lower fork. However, it did teach me what my job really required, and with an old-fashioned spring compressor and its properties, I was able to get the job done.