A&Q about 350Z
Q:
I have a 93 Maxima SE. I think I need to replace some of the lifters. Is it possible to replace just 2 or 3? Or do all 24 need to be replaced?
A:
I don't know if you can get them in kits of two or three... I would def go with getting all 24 and just replacing them.
A:
Due to expense in the past I have replaced single units. However, many imports only make them available in sets.
A:
Might sound stupid, so I apologize. He means the valve lifters, right? They're all in the cylinder head? Why not just buy another used cylinder head for $100?
A:
Are the lifters in the head? Sorry, I work on mostly domestic cars (they seem to break more lol). They are usually in the top of the block on top of the cam. An overhead cam would not use them as the cam would act directly on the rocker arms or valves.
BTW where do you get a good head for $100. I need to go there soon. Here in FLA its more like $200
A:
Actualy many Japanese Over Head Cam engines use some form of lifter/tappet between the cam and the valve, often with a rocker or similar inbetween (only its called something else, and Ill be damned if I can remember what, SAABJohn knows!).
A:
I think the word you're looking for is "follower."
I also do mostly work with American engines, so I'll give you my perspective on it until SAABJ shows up and gives us the right answer
For the most part, no. Cams (unless they are a roller lifter design) are hardened so the metal-to-metal contact doesn't chew the lobes. This hardening is only on the very thin surface layer or the cam. You can run on that thin layer of hardened metal for hundreds of thousands of miles, but you break through it and you're lucky to make it 100 miles. I use the analogy of an M&M. You can suck on the hard candy shell for hours, but once it breaks through, the whole chocolate center collapses in short order.
Lifters, followers, etc, establish a wear pattern on both their surface and the cam lobe. Introducing new lifters to a worn cam will cause it to establish a new wear pattern, most likely breaking through the hardened shell. You can imagine the mayhem that happens. In best case scenarios, you replace two lifters and you go on your merry way, or sometimes with light spring pressures, the cam lobe wear is slow and you can get a few metal shavings over the next few years and slow lobe wear. Worst case scenario like I found was catastrophic failure after a mere 230 miles.
A:
These are called "Followers" like Curtis said or "Tappets" usually by older people or British mechanics.