Northstar Engines and System Technical Discussion Discussion, N* cams in Cadillac Engine Discussion; Have the heads in the shop to be checked out. They say that some of the lifters are showing wear. ...
Automobile(s): 1997 ETC (GAVE TO STEPSON 2011), 2000 DTS (RIP)
FOUNTAIN HILLS, AZ
Re: N* cams
The problem is the cost to replace 32 lifters and 4 cams is a lot - probably more than it is worth. The rest of the engine must be showing signs of wear also, right? Unless they are shot - not just showing signs of wear - I would leave them alone.
The problem is that for some years the cams are no longer in production and can be hard to find. AJ has posted numerous times about finding bad lifters when doing HGs - I would assume you can just replace the lifters. I got lucky that the machine shop had two good used exhaust cams and the matching lifters. I would have them check the cams to see if they are still in spec and reuse them if they are good. If you can just replace the lifters I would consider going down that path but I don't know how much they become married to the individual cam or if that can cause problems down the road.
With all that said, remember that the cam lobes and follower faces are case hardened to a depth of .002-.005". If in fact the followers or cam lobes are showing signs of wear, from here on it's all downhill, because without the hardened faces, the faster the base metal is uncovered, the faster it wears, and on and on.
The hydraulic lash adjusters are static, no movement, no wear, and use oil pressure to take up slack in the cam/follower system. The pic is of a post-'00 setup, but you can get the idea of how the cam operates the follower to open the valve. A pre-'00 is in double jeopardy due to the lowering of ZDDP in starburst approved oils and also because the roller you see is actually just a highly polished smooth hump, no roller. You can regain the old additive package by going to a marine or fleet diesel 10W-30 oil. No change in oiliness, just the additive package, which the EPA doesn't want you to know. (Some say that ZDDP (zinc/phosphorus) destroys catalytic convertors. Curious they didn't seem to have any problems before the additive packages lowered 3 years or so ago.........and cats have been around for a long time.)