Ok so I'm getting ready to start assembly on my motor but I have this annoying feeling that the guy at isky cams was wrong I have a 280 mega cam that they helped me select but they said I would be fine running it with my stock valve spring... Here is where I am loosing sleep this cam has .565 lift will my springs really be able to keep up with this I have 049 heads with dual valve springs and I was not planing on turning this motor over 5-5300 help please if I need the spring I wanna order them now as not to hang up my build I wanna get out on the water befor the season is cometly over lol

Contact dr. Js in orange, ca does great head work but. Unless your running a roller cam stay under .540 lift. isky makes great cams but running flat tappet hydraulic cam with dual valve spring and lift in excess of 550 lift asking for problems.. Buy good quality lifters if sticking with this cam....good luck with your ride

I went from a Comp Cams 280H to a XM278H and the difference was incredible.  I'm sure the 280H was limiting the other work done to the heads.

It's all going to come down to what other components you have planned for your engine, and what you want to do with it.

Good luck with the choice.

Ok so I'm getting ready to start assembly on my motor but I have this annoying feeling that the guy at isky cams was wrong I have a 280 mega cam that they helped me select but they said I would be fine running it with my stock valve spring... Here is where I am loosing sleep this cam has .565 lift will my springs really be able to keep up with this I have 049 heads with dual valve springs and I was not planing on turning this motor over 5-5300 help please if I need the spring I wanna order them now as not to hang up my build I wanna get out on the water befor the season is cometly over lol

I just had an Isky 278 mega reground to a larger profile for an engine that I rebuilt, actually went to an advertised 294, but the engine is a stroker, 505 cubic inches, and the owner also upgraded heads, so the larger cam is appropriate.  This one has .560 lift, I don't see it as a point of failure, my cam grinder and I have been working closely together for many years with great results, never have had a legitimate cam failure.  (Did have a guy try to break one in with synthetic oil, I can confirm that will not work, and was not what I had recommended to him)

Now would be the time to confirm how much lift those heads are set up to work with, since they probably have been rebuilt at least a couple of times or so in their lifetime?  .040" is not very much, the number sounds large, but it's barely over 1/32".