Ive heard this from time to time ususally referring to small block chevys.......what exactly is this ???

Its a set of "booster" springs that go between the cylinder head and mechanical roller lifters so the lifters stay in contact with the cam at high rpm's without running extra valve spring pressure. 10 years ago someone tried this on hyd roller cams and was marketing a package for small block chevy's,i don't know if it ever caught on,haven't heard much about it in a few years,Smitty

here are some pictures of a 350 roller motor with a rev kit , the rev kit are the springs on top of the roller lifters and against the gold plate under the head . from what im told they keep the roller lifters in better contact with the cam. i hope this helps

Rev kits are mainly used on solid roller cams. Their main purpose is to keep the lifter from bouncing off the cam on the cams base circle. Basically, it keeps a small amount of spring pressure on the lifter when the valve is closed.

thanks for the replies guys.........a motor that turns what rpm should have one of these????......or do people still use them???

In my opinion, rpm is not the determining factor. I would run one if I had a solid roller cam. As I said, it keeps the lifter on the base circle of the cam during valve lash. On a hydraulic cam, the lifter is held done by the oil in it.

oh.....just thought by the name "rev kit" it was a high rpm thing......

One of the big purported advantages was that it allowed for lower valve spring pressure so the rockers would live. I thought the kits were built by Air Flow Research. They may still have them. As strange as it may be, I've never heard of a kit being produced for the big block chevy.

I used to run them on Big Blocks several years ago, One set I had was a crane and the others where made by Jomar I believe. They were used a lot in drag racing and truck pulling on engines with real heavy valve train components. I believe the circle track guys also use them because they will keep the lifter in the bore and on the cam if you break a rocker, etc.

I had rev kits in my 572's. They are very hard on cams. Too much spring pressure for long term use. I was told after I broke a cam they are best in high rpm applications like drag racing.