Question is if anyone can help would be great!
Would 280s work in a completely stock motor?
Would the valves be safe from htting the pistons?
Please help
thank you

 

yes it is fine, 280' have more duration as opposed to more lift.

 

It doesn't matter what cam you have with stock pistons, if a valve is open when a piston comes up in the cylinder you're going to have problems. The thing you should be asking yourself is, is the cam so aggressive that the valvespring will be unable to return the valve to the closed position before the piston arrives.

The piston is (mostly) irrelevant to this question. There are some extreme cases of dished pistons that might provide a _little_ extra wiggle room, but that's more of an academic argument. You shouldn't be basing your valve spring/cam combination there.

 

Alot of lift and alot of duration can lead to problems, however the HKS 280's are fine, as are most of the other "280" cam's out there. Just do your research.

I'm running 280's on a stock block/head with no problems.

 

+1 go for it!