What valve specs y'all like for adjusting

[HusseinHolland]

10 hours ago, Zed Head said:

The low clearance could be because the valve seats have worn.  Maybe due to unleaded fuel on old seat material.

People use brute force on the locking nut with a wrench and suffer busted/cut knuckles.  The parts up there are sharp.  I found that a small sledge hammer, like a 3 lber, used to tap on an open end wrench on the lock nut worked well for loosening.  There's room for an open wrench on all of the locknuts, you don't need the crow's foot adapter unless you want to get precise on tightening torque.

It's about as simple as it looks.  There's a threaded stud with a locknut.  Loosen the locknut, turn the stud, tighten the locknut, confirm lash.  After a few you'll realize that tightening the locknut pulls the stud up and reduces clearance a little bit.

There's a tutorial out there somewhere with pictures.  Can't remember the name, it might actually be linked in this thread somewhere.

Yeah, the motor has 250K miles on it. I'm surprised the compression is as good as it is, really. I'll recheck it after loosening all the valves back into spec range.

Thanks - So the large base nut (17mm) is the lock, then there is a 14mm? nut built into the shaft, I'm assuming, since it's tucked up against or under the rocker? I couldn't see it last evening. I'll look closer in better light. I'm used to MG/Volvo/Fiat/Honda layouts, which all had an obvious adjuster. I appreciate that tightening the lock typically reduces clearance, I usually shoot for the looser end of the clearance range when adjusting.

[Racer X]

26 minutes ago, HusseinHolland said:

Yeah, the motor has 250K miles on it. I'm surprised the compression is as good as it is, really. I'll recheck it after loosening all the valves back into spec range.

Thanks - So the large base nut (17mm) is the lock, then there is a 14mm? nut built into the shaft, I'm assuming, since it's tucked up against or under the rocker? I couldn't see it last evening. I'll look closer in better light. I'm used to MG/Volvo/Fiat/Honda layouts, which all had an obvious adjuster. I appreciate that tightening the lock typically reduces clearance, I usually shoot for the looser end of the clearance range when adjusting.

Yes, the 17mm nut is the lock nut, the 14mm is the adjustment.

 I’ve never torqued the locknut when adjusting the clearances, but as Zed points out, some people tighten the locknut way too tight.

As for tools, there is a wrench made specifically for loosening and tightening the locknut. It is made to be used with a ratchet, 1/2” drive if memory serves me. The Snap On part number is S6014. I see them on eBay occasionally.

I’ll try and post a picture of the tools I use shortly.

 

 

[SteveJ]

53 minutes ago, Racer X said:

Yes, the 17mm nut is the lock nut, the 14mm is the adjustment.

 I’ve never torqued the locknut when adjusting the clearances, but as Zed points out, some people tighten the locknut way too tight.

As for tools, there is a wrench made specifically for loosening and tightening the locknut. It is made to be used with a ratchet, 1/2” drive if memory serves me. The Snap On part number is S6014. I see them on eBay occasionally.

I’ll try and post a picture of the tools I use shortly.

When @240260280 was showing me how to adjust the valves, some were so tight that we both were pulling on it to break it loose.

[Racer X]

1 hour ago, SteveJ said:

When @240260280 was showing me how to adjust the valves, some were so tight that we both were pulling on it to break it loose.

It doesn’t take much to get the nut tight enough to stay put. Unfortunately, some hacks think if some is good, more is better.

In this case, it isn’t.

 

[Mark Maras]

 I agree. Over the years it always seemed that the lock nuts were tighter than I had tightened them. I found that just giving the wrench a good bump (not enough to hurt) with my hand would secure them. 

[Jeff G 78]

I have never used the special bent crow's foot wrench.  I've always just used two open end wrenches and snugged the lock nut.  After hundreds of adjustments over a dozen cars and 40 years, I've never had one loosen.  Of course, I always check the clearance after it's tight to make sure it is still correct.  After a while, you get a feel for how loose to leave the clearance so they tighten just right when the lock nut is snugged up.

[siteunseen]

Something I realized after a couple is when tightening the lock nut the adjuster nut will turn and get the spec off so I always hold the 14mm adjuster while I tighten the 17mm lock nut.

Another thing I do that most people laugh at but why not? . Our motors are tilted pretty hard if you look so I've marked the center off my cam towers with a Sharpie and get the lobes lined up with my mark instead off straight up. It's one of those why not OCD things but...why not.

[Racer X]

The tools I use for adjusting L series engine valves.

Snap On S6014 17mm offset crowfoot adapter, 1/2” drive ratchet, 14mm open end wrench, feeler gage holder with two stepped “go-no go” feeler gages, .007”-.009” (for .008”), and .009-.011” (for .010”).

Not shown is the starter button I use for rolling the engine to get the cam in position to set the lash, or the speed wrench I use for removing the cam cover. Also, when number 1 cylinder is at TDC, several other valves can also be set. The base circle of the camshaft lobes is at zero lift for more than 180 degrees of rotation, and as long as the follower is in that area, it can be set. I haven’t run a set of valves for a long time, but it stick in my head that I could get all of them adjusted and only set two or three cylinders at TDC.

 

 

Edited March 22, 2023 by Racer X

[HappyZ]

I updated the spreadsheet to make it a bit more explanatory.  After not looking at it for awhile, I had a time figuring it out.  I hope this helps.

Print them both out and tape together to make one work sheet.

280Z Valve Adjustment Chart v3.pdf

Edited June 2, 2023 by HappyZ

[Zed Head]

1 hour ago, Racer X said:

feeler gage holder with two stepped “go-no go” feeler gages, .007”-.009” (for .008”), and .009-.011” (for .010”).

That is a cool tool.  No more fiddling around with two different gauges.  

This thread has the spectrum from cold adjustment, take-your-time and get it right, up to hot, I-know-what-I'm doing get it done.

[HusseinHolland]

Finally got back to the valve adjustment, now the car is back on all 4 wheels. I just bump the motor with it in 4th gear. the car is so light I can push it forward with one hand on a tire - went 1, 5, 3, 6, 2, 4. 

I also bought the silicone VC gasket, but didn't read the install directions until I was ready to put it all back together. I found that it has to be "glued" to the cover with RTV. SO, It's not going to be finished until tomorrow

One of the locknuts was so tight I took a chunk of skin off my finger on the metal cover next to the battery. Most of the rest were barely tight. No valves were within cold spec, all too tight. couldn't even get the .008" in the exhaust rockers. They were all at least 1/2 a flat too tight. I set all intake @ a snug .008" and exhaust @ .010". I did torque the lock nuts to 36ft/lb, based on the range given in the FSM. Definitely fiddly, as I found it very easy to end up with the valve too tight again, when snugging the lock nut.

Edited June 1, 2023 by HusseinHolland

[Yarb]

Talk to me about the Silicone valve cover gasket. Interested to know why you would not go back to the factory gasket which is reusable. Thanks for your time…john