For a while now the old 390 has been hitting a wall at at 6200rpm. If I persist it bends pushrods. It used to spin to 7000rpm with no issues so I thought a valve spring check would be in order. I bought a pressure checker from Summit ages ago and have only just got around to making my insitu tool. Here are some pics.
Machined down some old rockers and stands, welded the rockers together, cut and old 1/2" square drive socket and welded it to the rockers and made a cup for the spring checker to sit in so as not to damage it.
To check spring pressure you need to stack 2 stands and an extra 15mm spacer.
If the springs need replacing then remove the extra stands and checker and the tool can be used to pop the collets.