do i need special bearings for roller cam?
is there anything like roller-cam-bearing?

no

T,
They do make "roller" cam bearings but the block must be bored larger to accept them. My engine builder has done it a few times but only on all out drag race engines.
Most people run standard cam bearings on roller cams.

thnx;
i was looking for different length pushrods on a web page then i saw this roller cam bearings ,i was a bit suprised cause its the first time i heard it.

If there was no picture they resemble a very thin wheel bearing , with tiny needles surrounded by a cage keeping them in place. The inside diameter is the same as a standard bearing and use the cam for the inner race. The outer race is larger than standard and is pressed into the block like a standard bearing after the block is bored to accept it.

yep i saw it
thnx for help

You do not need special bearings togehter with an rollercam. But you MUST use an bronze gear on the distributor and an anti walk bushing in the front of the camshaft if you run regular chain. An wearplate between the block and camsprocket is recommended but needs maschining of block or sprocket. Same manufactors make kits with sprockets which are ready maschined for and comes with an bronze wearplate or an axial needle bearing (Manley and several other).
This feature is "built in" for example the good expensive Jesel drives.

The lobes an an flat tapet camshaft are grinded in an small angle from the centerline of the camshaft to give the lifters a rotation (good for cam and lifter wear). This gives the cam an axail force which push the cam towards the back of the engine.

A rollercam does not push the cam toward the back of the engine because the lobes are grinded parallell with the centerline of the camshaft. Roller lifters CAN/SHALL not rotate around its centerline!

Crane uses a press on cast iron distrib gear on their cams so you do not have to use a bronze dist. gear. Not sure if that is true for all of their cams.

Tim,

the babbitt press-in bearings that go in the block are no differentfor a roller cam.

As US1 said, SOME billet roller cams us an IRON distributor drive gear, which works fine with a standard distributor gear. If the billet cam has a steel gear, however, then you MUST run a compatible gear on the distributor shaft (bronze some proprietary gears per your cam mfrs advice).

Now, a roller cam will WALK back and forth in the block, and this must be restrained (unless you plan to go with a distributorless ignition). Typically, a billet timing gear in conjunction with a torrington roller bearing is used between the front gear (sprocket,actually) and the face of the block. This will prevent the cam from traveling "back" into the block. A needle bearing camshaft "button" on the front of the gear will press against the timing cover (a stiff aluminum cover is recommended) to keep the cam from walking forwards. Set the clearances to allow no more than .005" of cam walk. This will prevent your ignition timing from varying wildly at high rpm due to unrestrained cam walk.

m

I have Comp.Cams in mine with the same deal. Ran Merc TBIV distributors all season...no problems.