cmysix

iTrader: (2)

here's the cam specs, any educated guesses on how much smaller the base circle is on this cam compared to a stock LS2 204/211

G Atsma

Comp should be able to tell you since it's their cam you show here. Most after market cams are ground on the OEM-sized base circle. If the cam grinder says you can use stock pushrods, it's likely on the stock base circle

01CamaroSSTx

iTrader: (3)

Well if all your changing is the cam and from the looks of the cam spec's your stock springs will be fine your PR length should be the same as stock.

AndyTA

Cam base circle generally *only* changes if Lift is increased/decreased.
Lift increase = smaller cam base circle
Lift decrease = larger cam base circle

GammaFlat

iTrader: (1)

From a purely theoretical standpoint, the base circle determines the maximum lift possible (base circle plus lift cannot exceed the diameter of the camshaft bearing journal - circled in red). Otherwise you couldn't slide the cam into the block.
So... previous posts stating that increasing lift decreases base circle is likely true. This is based on the assumption that the cam grinder always puts the maximum lift at the height of the cam journal.
Maybe someone here can tell us how much the LS engine cam journal increased over BBC and SBC?! This is great news as the geometry and mechanical advantage of a larger cam journal and therefor a larger base circle is easier on the valve operating hardware which translates into higher potential RPM with lower chance of bad consequences.

G Atsma

Most stock GM cams have a lift peak that is still well within the journal diameter, which enables cam grinders to stick with OEM base circle dimensions. This is why stock-length pushrods can be used with so many aftermarket cams.
Back in the bad ol' days before cam grinders could get blanks, cams were reground by reducing the base circle to enable higher lifts.