Z24 valve clearances

[Kennyt]

I understand the valves should be adjusted with engine warm/hot. What should starting cold clearances be since just had head redone?

[Doctor510]

.002" tight

[datzenmike]

I only have the L4 cylinder clearance and the L24 is just two extra cylinders. Same valves, cam lobes and rockers so 0.008" Intake and 0.010" cold. This is fine for a start up, but assumes that the hot setting will be 0.010" and 0.012". Only way to be sure is to re-check when they are hot.

[Rhino13]

Look on the bottom side of your hood, there should be a sticker that tells you valve lash. My truck is at my work right now so I can't go check it, but I'm pretty sure hot it's 0.012" int and exh if I remember correctly. Make sure you have cylinder #1 at TDC for 1,2,4,6 then cylinder #4 at TDC for 3,5,7,8 when adjusting.

[Kennyt]

Thanks all for the information

[datzenmike]

Sorry I gave L series clearances. The Z24 is 0.014" for all valves. (per '84 FSM)

[Charlie69]

Hot or cold?

[datzenmike]

Always hot, this is the FSM recommendation.

[720inOlyWa]

Look on the bottom side of your hood, there should be a sticker that tells you valve lash. My truck is at my work right now so I can't go check it, but I'm pretty sure hot it's 0.012" int and exh if I remember correctly. Make sure you have cylinder #1 at TDC for 1,2,4,6 then cylinder #4 at TDC for 3,5,7,8 when adjusting.

 

 

Funniest thing, the underside of my hood was kind of grungy until recently. Somebody had rattle-canned some flat black onto the underside leading edge of the hood in a furtive attempt to delay hood rust, which sort of worked. I yanked what was left of the fiberglass matting attached to the hood, which was disintegrating in hunks anyway. Finishing up the basic clean up, I used mineral spirits to degrease and in no time, discovered the vital engine statistics sticker- in great condition- still ‘on the job’. It is so cool that they put this nice little compact reminder cheat sheet, right where you need it! I totally resto-ed mine, immediately and with great reverence.

[datzenmike]

Some also have the emissions and hose line runs.

[Rickie B]

Yes,my 85 720 z24 has all these stickers,says valves .012 hot intake & exhaust

[Rhino13]

I recently adjusted mine out to 0.014, although in both of my service manuals and under the hood it says 0.012. It was very clattery but ran about the same, so I put them back to 0.012 and it's much quiter.

[Kennyt]

I adjusted mine to .010. Comp cam tho. Seems to ne quieter a bit

[datzenmike]

If the valve lash is too wide there is noise and potential damage as the rocker slams into the steeper slope of the cam profile.

 

If the valve lash is too thin there is less time for the valve to seat against the valve seat and this rest time is how the valve cools itself. Heat is transferred to the seat by direct contact. More than that, too little clearance can be reduced even further by sudden heat spikes during driving that can eliminate the clearance even further. If the valve is barely closing it will not only over heat but the valve does not seal the cylinder properly also. Combustion gasses can carve a path and erode the face or seat 'burning' and exhaust valve. On an intake it can cause a backfire under load and in both cases a loss of compression.

 

If you have an after market or stock cam follow the maker's recommendation for clearances.

[a15egi]

Hi guys. Im having nissan pathfinder/terrano with z24 carb. 

Setting the valve to 0.30mm (hot) and there is still valve noise when the engine is hot. 

Should I set the clearance to lower than 0.30 mm? Like 0.25 mm?