Topic: valves/cam in 15h.p ohv

[mtd91]

My dad told me that I dont need a g team cam.He said all it does is make the valves go out further.So he says all I need to do is put longer valves in.Is he right?

[mowdak1]

Wrong!

Cam not only extends the lift... (makes the valves go out farther)
It also extends the duration... (makes the valve stay open longer)

In fact the lift really isn't extended that much, it's more about holding the valves open a little longer to allow the engine more time to breath.

Longer valves would not close, thus there would be no compression, and it would not run. Not to mention they would likely hit the top of the cylinder and knock a hole in it.

[CaseRacer969]

Don's Cam or any other performance cam will usually open the valves a little further (lift).  The cams are also designed to open the valve sooner in the rotation and hold it open longer (duration).  The combination of the two allows more air/fuel mixture to be compressed in the cylinder and makes more power.  I use a cam from Precision Cams and the stock length valves work fine.  I do highly recommend stronger springs and retainers with any OHV engine.

Jack Jones
Hard Case Racing

[mtd91]

Thanks I thought he was wrong but I was just checking to make sure.