more questions for yall :P, roller cam bearings....

[Bandit72]

http://cgi.ebay.com/ebaymotors/Mopar-Race-Roller-Cam-Bearings_W0QQcmdZViewItemQQcategoryZ107070QQihZ012QQitemZ220053936987QQrdZ1

http://cgi.ebay.com/ebaymotors/Mopar-Race-Roller-Cam-Bearings_W0QQcmdZViewItemQQcategoryZ107070QQihZ012QQitemZ220053939602QQrdZ1

found these on ebay...never heard of anything like them...

are they something that wears out fast and needs replaced often?
is there any extra machining that needs to be done for them to fit?
which ones would i need for a big block?

thanks Ryan Olson
i'm sure you guys are tired of all my questions but i figure if i'm gonna build my own engine i want to do it right the first time....

[Chryco Psycho]

just use normal tri metal brgs , the friction is between the oil & brg surface , by using a roller brg you take away 90% of the brg surface & do not reduce friction , the normal cam brgs are so soft if the cam actually touched them they would fail very quickly , the cam runs on a film of oil only

[Bandit72]

ok, thanks...