how much lift can stock springs handle safely?

 

SE255 cams or comparable is about it.
If you go to your cam choice site it should tell you what springs that will be needed.

 

No more than .560 safely if you want to run it at the rev limiter a bunch.

SE257 cams have .569 lift and they recommend performance spings for them.

 

I have woods tw5-6 cams in mine .575 lift. stock springs. no problems 09 ultra.

 

I ran .575 no issues but wouldn't go higher than that. Seems to be the accepted upper limit.

 

.585" is max from what I read. I know they will work with the .575 lift of the TW 777 and TW 888 and SE 259E as there are lots of them running with stock beehive springs. Most people don't go past 5500. I suspect if you went to 6500 you maybe pushing the spring rates and float the valves and eventually beat the valve seats out. What floating the valves is is when the lifter actually doesn't follow the cam face causing the valve to bounce like hitting an anvil with a hammer, it will bounce. The heavier the valve train is, the more spring pressure it takes to keep the lifters on the cam.

 

I wouldn't go over .560 with stock springs? From what I've heard stock heads can't flow that much lift anyway?

 

Kevdon,
how do you like these? I have been seriously thinking about them, for on paper they look like they let the 103 breathe very nicely. Thoughts?
Thanks

 

There is more to consider than just lift for valve springs. While maximum lift is important its not the only factor. Maxium RPM and cam ramp rate are also factors that should be considered. Your valve springs have to control the valves at all times not just at maximum lift.

It's best to follow the recommendations of the cam manufacturer or your engine builder (hopefully they know what they are doing). Most cam manufacturers will tell you if the cam is "bolt in" and acceptable for use with stock springs or if a high-lift spring is required.

FYI - The current beehive springs HD puts in as stock are pretty darn good springs and you'll have to get pretty agressive with your cam to need to swap out your stock valve springs.

Good luck.

 

I'm running fueling 574 lift cams with stock spring and I have friends running S&S cams with .585 lift with stock springs. I was talking with my engine guy the other day and asked if he had seen Fuelings 595 cam and he said I would have to change the springs for sure with it. I am not saying its the right or wrong way but 585 lift would be the max I would go with stock springs.