Ethans Head Swap

Nissan 300ZX technical discussion forum: Maintenance, performance, installations, modifications, how-to's and troubleshooting.
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es.biggs
Posts: 2120
Joined: Sat Feb 20, 2010 10:32 am
Car: 1990 300ZX 5sp NA
Location: Charlotte, NC

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Hey guys!

I bought some used heads from a guy the other day. I figure I'm going to have a lot of questions so I just made this thread and I'm going to post all of them in here.

While the heads are out I figure I should go ahead and do the valve stem seals. The valves from what I can see look to be in great shape, and doesn't appear to be any major pitting.

I haven't removed them yet, and I want to make a game plan before I do it.

1. When the valves are removed, should I clean them? With what, a wire wheel? or is that too abrasive?

2. I'm not getting the valves/seats ground unless there is no other way. Should I re-lap them back into the seats or should I just put them back in the way they are without lapping? As long as I put the same valve into the same seat it came from everything should be gravy right?

I know valves usually rotate in their guides, naturally, so it wouldn't matter how the valve goes in as long as it's where it came from...is the same true with our heads (do the hydraulic lifters make a difference?)

I know it would be nice to get the valves and seats ground, but I just don't have the money for that. After buying the 60k kit, the gasket kit, and the heads, I really am close to selling my body to fix this car :help: lol

Also, it looks like the PO cleaned the head gasket material off with a whiz-wheel...the surface is very shiny, clean, and smooth. No warping either. Is there any reason to have the heads decked? I'd like to avoid that if possible so I don't increase the compression.


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evildky
Posts: 14225
Joined: Sat Jan 31, 2004 9:23 pm
Car: 71 Datsun 240ZT
87 Nissan 300ZX N/A-T
06 Nissan 350Z GT
Toyota Tundra TRD RW
Location: Louisville, KY
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before taking the heads apart, turn them over and fil the combustion chamber with gas, then look at the intake and exhaust runners for any gas that leaks though, if any of them leak you'l have to do something about it, if there si no leaking I'd leave the stem seals alone, if you plan to remove the valves then should be lapped in and retested for leaks, and no clockign has no effect, lapping helps to ensure the valve and seat are both perfectly round


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