what is the biggest cam i can run on a gm502/AFR head bbc without problems with the stock lifter setup?crane cams website says upgrade to aftermarket lifters beyond .570 valve lift with 1.7 roller rockers,could i use 1.8 roller rockers to get more lift without any problems?

Originally posted by awesomedre:
what is the biggest cam i can run on a gm502/AFR head bbc without problems with the stock lifter setup?crane cams website says upgrade to aftermarket lifters beyond .570 valve lift with 1.7 roller rockers,could i use 1.8 roller rockers to get more lift without any problems? =
Danny,
Yes you can use 1.8's.
You will need to change the springs from the standard ones with a hyd roller.

whats the biggest cam you would use with the 502 stock roller lifter setup wolfplace, thanks

About .335" of lobe lift is all you can use with the factory roller setup; any more than that, and the lifters may fall out of the dog bones. Remember, to make a cam "bigger", they don't make the tips of the lobes taller; they're all made about as tall as they can go and still install through the cam bearings. Rather, what they do, is make the back side smaller, which makes the lifter retract farther into the block when the valve is closed.

I'm running a Crane cam (pn 168731) with .587"/.610" lift with the stock ZZ 502 lifters without a problem. I was told by Crane at the time that it wouldn't be a problem. I notice now that they recommend changing the "stock" lifters for this cam. I checked the lifters when I built the motor and they never dropped below the tops of the link bars throughout the cams complete rotation. The motor runs great, but I haven't put a whole lot of miles on it either. Maybe the lifters that come with the ZZ502 are longer than the ones in the HO 454/502 and can handle a little more lift? Pace Chevrolet states that the stock ZZ502 lifters are good to about .600 lift.

Tom

It depends on how the cam is ground.
As RB said, .335 cam lift, as I recall is the safe number in almost all cases but if the cam is ground so the base circle isn't reduced this can be increased a small amount. You are only talking .017" to get to .600 lift.

You need to let the cam manufacturer know what you are planning & hope you are talking to someone there that has a clue... :D

But it is still a reasonably good idea to check for yourself as Tom did ;)

The cam base circle has quite a lot to do with it. From what I have gathered, the controlling factor is total lobe lift and base circle which is actually a good thing.

thanks for the info guys