HP and changing lifters and rockers
I think that the factory hydraulic roller lifters are excellent pieces. I have run the stock ones in my highly modded '87 IROCZ for 18 years. And in my '99, I have documented 400 RWHp and trap speeds of 117mph and shift at 6500 rpm, they have held up very well also. However, I think that the stock LS1 rockers will suffer a needle bearing failure. Some I have read on here at about 80,000 miles, but then again, these are highly modded engines.
Does this help ?
As for the rockers, I couldn't get a decent wipe pattern out of the stockers and have gone to roller rockers as a result. The bearings were less of a concern then was the potential for accelerated guide wear with a rocker that wasn't placed correctly on the valve stem and much higher spring loads. Again, stock rockers are good pieces, but they were designed for lower spring loads and therefore the tolerance on the wipe pattern was not as critical. Start upping the over the nose spring loads and wipe pattern gets more critical in a hurry.
None of this is related to hp but rather the installed setup of the valve train you are running. Z06 valve springs will provide good hp with the right cam but don't provide nearly the valve train loads as something like Comp 921's.
The issue with the lifters being lowered .050" is probably not a serious concern unless you are talking about a max effort engine. The rocker issue is about the same. That said, the details are what makes the difference...
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IMHO if your going to do anything, change the springs first.
Rolling rockers? YES
I am using the Comp Cams #1500 rocker system and it is the "bomb".


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