what is max lift for stock rockers?

[crash]

what is the biggest lift cam you can go with without adjustable rockers??  on a 440

think i could get away with a 494/513?

[aifilaw]

it depends on whether you had a solid or hydrallic cam, but in either case you should be fine with that amount of lift, the rockers will do around 0.55, the springs will go about 0.54 in my experience, but I wouldn't leave them on something that will see more than 5000rpm on that setup for more than 5% of its time or you are begging for failure.

[Challenger340]

This may be "off-topic"
But,
I'd be a little more concerned about the stock rockers living, with the added Spring Pressure/Rate required to keep up with a Cam on the .550" Lift range ?

[aifilaw]

once again, if were talking about the old stock iron ductiles, they can survive darn near anything (not talking about springs here, but spring pressures, speeds, et cetera. They won't perform as well as a roller, but they will darn sure out-live it.

As far as the stock stamped rockers, the rockers themselves will be fine for most applications up to around the .5 range. I've personally put quite a but of spring and rebound rate onto them to the tune of a 4.5 ramp cam, but never took it above 5000 rpm (torque build).
I've never actually had a stock stamped rocker fail, but then I've never been crazy enough to attempt using them in a 0.6" camshaft, rather I just get a 1.6 or 1.7 ratio new rocker if I want that kind of lift, and I wouldn't even bother with them on an engine that will see 6,000 rpm on a regular or even semi-regular basis because its just robbing you of power a true roller would grant.

[Challenger340]

Apologies, ME BAD !

I thought we were talking about the stock "stamped steel" Rockers ?  Sorry.
I didn't think they'd "live" @ rpm and pressure.

As Aifilaw mentioned, The Ductile Iron things are Fine for just about anything, IMO too.

[firefighter3931]

what is the biggest lift cam you can go with without adjustable rockers??  on a 440

think i could get away with a 494/513?

The stock style non-adjustable rockers are fine with that cam profile 



Ron