No ….. valves do not compress, if you are lucky they just bend but most times they break and the piston shatters ~ explodes, puts the rod through the block and piston bits get spat up into the inlet manifold and get sucked down into the other cylinders as it turns over that last revolution or so and seizes ……….. now your block is completely stuffed, crank bent and heads are most likely cracked too from the piston trying to compress lumps of broken steel bits into them. As you might have guess by now it has happened to me ……… completely stuffed a brand new reconditioned engine and I was not giving it a boot full either, my wife was just putting home from work in peak hour traffic when it let go……………

The other tendencies of standard rocker arms, especially the cast iron and fulcrum ones like for example on the Ford Windsor and small block Chev is that even with one step up from standard in a stiffer valve spring the bottom of the rocker arm breaks and falls out ……… been there had that happed too ……… This can happen on as little as a commonly installed and popular street set up being the LT1 Chevy valve spring with inner dampener of a typical rate of 90 to 100lbs closed set pressure, which is fairly tame and typical for a mild performance ground camshaft.

OK I here some of you saying now……” but I have run stock valve train components and have not had any problems with lumpy cams” …………. And so have I ……… you see the thing is you never know when it is going to let you down, but when it does, the cost of the damage far out weighs buying the right valve train components in the first place………………. Ron.