Noisy Tappets?

[240paul]

Thanks for all the info!

One thing I did notice is that all the inlet pivot posts are about 2 turns higher than the exhaust ones. And all the exhaust lash pads have a centralised wear pattern

The picture I posted was a rocker from an inlet valve.

Thinking about the valve train a bit deeper - am I right in saying that the pivot post retaining spring actually keeps the rockers against the profile of the cam at all times? - So any actual noise would be due to the gap of the rocker arm where it sits on the lash pad?

I am just trying to work out from an engineers POV where the noise is coming from. On the other thread it went into detail regarding lash pad height affecting the valve timing to which I understand. But if the clearances were the same regardless of what size lash pad, why would there be more noise?

Thanks

Paul

[240paul]

From http://www.courtesyparts.com/

.180" Lash Pad (1 pad) (12 Required)

Code: 99996-M1180(S30)

Price: $3.00

I know I will have to check for the right sizes but are these the right type??

Paul

[24OZ]

Paul,

I have both those books Keith suggested and I hadn't thought of checking them :stupid: .

Both books go into pretty good detail on the lash pads and sizes.. I can phocopy you the relevant pages, once I get back to work, on Wednesday.. Let me know if you want me to do this and I will mail them to you, courtesy of works franking machine .

G.

[2ManyZs]

Those are the right type, you only need to find out for sure what thickness you need. I think I read that the stock ones were ~.120 or there abouts.....

I'd say that the majority of the noises you are hearing are coming from the valves slamming shut. If you think about it, the cam lobe is running off the rocker and the valve is then slamming shut, instead of having the cam lobe close it slowly, which is your duration of the cam.

It doesn't surprise me that some of the rockers seem OK while other are not, all due to the differences in valve stem lenght, however minute. Somewhere along the way perhaps some of the valves were replaced with aftermarket valves which were just a bit off the factory specs...

[240paul]

George,

Thanks for the offer - that will be greatly appreciated :classic:

Keith,

Seeing that the rockers are new and the lash pads have wear on them - the new rockers are beginning to wear into the "wear" of the old lash pads, I will try replacing all of the lash pads as this is a cheap and easy thing to do.

On the noise issue you was talking about - would there really be a difference between hot and cold?

Will let everyone know what the outcome is!!

Paul

[2ManyZs]

Doubt if hot or cold would make much difference in the noise since it's not really a clearance issue. It's more of a valve closing issue that is making a lot of the noise since they are closing too rapidly because the cam lobe is running off the end of the rocker like that.

Once you get this straightened out, I'd say the performance of the car ought to increase since you are not getting near the proper duration of the cam and only half the valves are truly in time with the engine.

[ZXatlast]

Greetings Guys!

I am a just brand new, and first time 1979 280ZX owner. It's taken a while, but I'm 'here' now. New to Z's altogether, really. And just now joined this forum too, so I'm still finding my way about.

A simple question, I hope, if I may.... The bloke I bought it from spent over a grand and a half having the head reconditioned for its still-in-place original L28e engine. All well and good. However, the tappets -- is that a term you use? I'm referring to valve clearance -- are a bit noisy. I am quite happy to get in there and make the adjustments as a first step (I say "first step" because I am hoping I'm not going to get the other issues being discussed here).

However, adjusting those clearances, according to the factory manual, requires a special tool I didn't notice any of you referring to that tool, so I'm hoping it isn't needed. And I haven't taken the rocker cover off yet, which might make the answer to my question visually obvious, but, since I'm here, my question is, is that special tool mandatory? Just judging from the not-at-all-detailed pics in the manual, you should be able to do the same thing by manipulating an appropriately-sized standard spanner into the right place.

I would be very grateful for advice....

All the best,

Steve

[Diseazd]

zXatlast.......The special tool is a simple feeler gauge. If the bloke that had the head built had the work done at a reputable rebuilder, the rocker geometry (centering the wipe pattern) will have already been done. If not, you'll need to make sure that it is set up properly or you'll experience the same problem as above. Find out who did the work and if rocker geometry was set up. if it wasn't, you're in for a learning experience. Welcome to our fraternity! Guy

[ZXatlast]

Thank you Diseazd, very much.

With great respect, though, the pic in the manual isn't overly informative; I've just gone back to the manual and it refers to a "Pivot Adjuster ST10640001". It is seemingly a torque wrench looking device and where you'd attach a socket it has a long-ish arrangement that ultimately fits around the pivot.

Now, I haven't yet seen these pivots in the metal, so if they have a 'normal' hex-shaped surface to adjust them by, for instance, then all will be fine. But if the place you grab to adjust them is some strange other shape that a spanner never fits, then it becomes more, umm, interesting.

But as I said, you guys never refer to it, so I'm hoping that the special tool just makes it easier than manipulating a standard spanner in there.

Just for the record, it states that the clearances - adjusted hot, and it says operating temp hot(!!), as opposed to warm - is 0.25mm inlet and 0.30mm exhaust.

And thank you for your welcome, I hope it'll be productive both ways. When I get my profile done, obviously I'll put a picture of my 280ZX up in it's current condition, which is pretty damn good for a $2250 outlay; fully usable and rego-ed til May.

All the best,

Steve

[Diseazd]

Steve.......Pick a valve....any valve......turn the engine over where the lobe is straight up.......now with two open end wrenches, loosen the two locking nuts securing the pivot ball. I believe one is a 17 mm and one is a 14 or 15 mm open end wrench. Once you loosen the two lock nuts you can turn the pivot ball up or down to adjuct the clearance between the rocker and the heel of the cam lobe. You check by sliding a feeler gauge between the rocker and the heel of the cam lobe. Clearance should be .008 intake and .010 exhaust at cool temps. It ain't rocket science. Once you get the clearance right,you lock the two nuts together....but continue checking as you tighten them down because they change as you tighten them. Play around with it....you'll soon get the hang of it. Good luck.....looking forward to seeing your Z. Guy

[jmortensen]

Pop an intake and an exhaust rocker off. Clean it and use a marker to color the friction surface black (don't know if you have Sharpies down under, but that's what I used). Reinstall the rocker, adjust the valve, and turn the engine over a couple times. Look at the pad on the rocker, and you can see if the wipe pattern is centered. If it is not centered, sacrifice a feeler gauge. Cut it into strips and use it like a shim between the lash pad and the rocker. When you get it to the right thickness, your wipe pattern will be centered. Add the thickness of the shim stack to the thickness of the stock pad, and then you know what size lash pads you need so you don't need to order extras. Some engines take a different pad on intake and exhaust, but if your machine work was done correctly, all of the intakes should take the same size lash pad, and all of the exhausts should take the same size lash pad.

It's time consuming, but not difficult to figure out. Some people will say to do the marker test with machinist's blue, I like the market better because it doesn't smear as much.

LOTS of info on this over at hybridz.org. That's where the cutting the feeler gauge tip comes from.

Edited February 21, 2011 by jmortensen

[Diseazd]

Jon.....I think you're way over his head......this is his first Z......one baby step at a time!