z24 valve adjustment?

[mikec]

valves have been noisier than shit on my z24, so i'm assuming it uses rockers instead of lifters, but to be honest i haven't done any work on this motor. anyone know the feeler clearances? i haven't popped the valve cover off but i'm also assuming it's a normal rocker/eccentric/nut setup?

 

thanks,

 

mike

[datzenmike]

In and Ex hot setting 0.014"

 

No lifters. The rocker arm rides directly on the cam lobe. At the valve end of the rocker is an adjustment screw and lock nut.

 

The noise could also be timing chain slack. I've heard 720 owner's say this is how the Z engine tells you it want's an oil change. There is a spring loaded chain tensioner that also operates with some hydraulic oil pressure. When the oil gets old and dirty it may have an effect on the tensioner too. Anyway several have mentioned that after an oil change the rattling went away.

 

 

The FSM recommends that the head bolts be loosened, ONE AT A TIME ONLY, and re-torqued to spec. (60 ft. lbs.) at every tune up to maintain clamping pressure and prevent the head gasket from blowing. Z24 motors have a history of blowing the h/g every 100k. This must be dome on a COLD motor and in any order.

[mikec]

wow, great post. do you have a picture of the rocker assembly? are they adjusted with an allan/coathanger? also, do you have the cold settings?

 

the headgasket and bolts are all original and have never been touched. by one at a time do you mean loosen then retighten each or loosen all of them one by one?

[datzenmike]

In any order, loosen and then tighten to 60 ft. lbs. If done this way you do not have to follow any sequence because the head isn't being loosened fully.

 

Generally the valve are set about 0.002" or 0.003" less to allow for heat expansion. I don't have the number for a cold setting and this can be used for a rough setting when re building to get the motor running. Valve lash should best be done on a hot motor. It can be done quickly befoer the engine cools by setting the motor to TDC (both #1 valve lobes pointing downward) and adjust...

 

In and Ex on #1, In on #2, Ex on #3

 

Turn motor over one turn (or TDC with #1 cam lobes pointing upward) and adjust...

 

Ex on #2, In on #3 and In and Ex on #4

 

done

[mikec]

Alright, I had always been under the impression it was more consistent to do them when cold, but ill try it hot. It'll be nice to do it on an 4cyl for once. Thanks for the input.

[Not 420 Just 720]

I Also need the valve adjustment job for my 86 720. where can I take it to get it done in the L.A area?

[datzenmike]

Christ on crutches... it isn't rocket science. For a small fraction of the price of having it done you can buy the tools and do yourself. It's very simple and besides the satisfaction of doing it any time you wan,t i costs nothing. You need a screwdriver and a spanner. Probably 15mm and a set of feeler gauges set to 0.013".  These old vehicles are older than the mechanics that work on them. You would know as much as they do so don't pay money for them to practice on your truck... learn to do the maintenence yourself.

[ggzilla]

It is more consistent when hot. Because what is Cold? 95 degrees? 55 degrees? Yet hot is controlled by the thermostat same temp every time.

 

It is easy to do. The first time I was worried but it worked out fine. Just double check the final setting by ensuring the next bigger size feeler won't slip in. That's the biggest beginners mistake, setting it just a tiny bit loose so that it's noisier after they are done!

[Nevyn]

found this to be very helpful in regard to the order of which valve to set...thanks :-)
car still won't start, but at least the valve clearances are set