The block should be a roller block. My 88 K5 had a stock roller block. You will need the roller cam stock roller lifters, new timing chain and the spider web to hold the lifters in. Not sure on the push rods, you might need special length. You can usually find the setup on EBAY.
The only way to know if you have a roller motor is by the engine code in the VIN. I don't recall what the letter is that indicates roller, Mine was "K". You will know once you pull it apart as well. I rebuilt my 89 350 which is not a roller motor. Meaning it has hydrolic lifters with no rollers on them. 91 motor may be a roller motor. Just check with the dealer and they should be able to tell you or I'm sure someone on this site as well, unfortunately not me. There are some advantages to roller motors, tend to lengthen the life of the cam/lifters. Increases power slightly since less drag. The cost is the factor to consider. Typically roller motors are significantly more expensive to replace moving parts such as cam/lifters. If that doesn't bother you then disregard. It is always fun to upgrade. Good luck.
Right, thanks alot for all the help, guys. That is what i thought it was, "roller ready". Have heard a few conflicting views, but i am sure you are right about not being factory roller, so that is what i will expect! With having provisions for the roller, does any machine work need to be done?Will find out for sure when I /forums/images/graemlins/hack.gif into it!...
i do not know this for sure, but thought i would mention it, from what i understand, roller cams were only put into cars in that year, and were introduced to trucks the first year of the vortec, 1996. what exactly is the difference in a roller-ready block, and a roller-not-ready block?
This comes from my experience in putting a roller cam in an '89 Sub. The roller block has lifter bores that are not as tall as the non roller blocks. Also, the roller block has bosses in the lifter valley to mount the "spider" that holds down the bars that retain the lifters in their respective lifter bores. On the block I dealt with, the bosses for the "spider" were not drilled and tapped so that had to be done at the time of the transformation to a roller cam.