A Z24 head question...

[Sick720]

Well I've blown three head gaskets in about two years, and had the head resurfaced twice. Well this last time I had the valves ground and putit all back together. Started right up, but! There's a problem. It has a hard miss at idle, that sounds like a valve lash problem. And a knocking that sounds like loose rocker arms. But they're spot on. So... Anyone have any ideas, mabe a cam lobe getting wore down? Sticky lifter? All I know is it's getting really annoying lol.

[datzenmike]

No lifters to stick the rocker arms ride directly on the cam lobes.

 

Head resurfaced will add chain slack. Normally the tensioner can adjust for this. Z24's are known for blowing HGs every 100K or so. You could try re torquing the head bolts every tune up but make sure the motor is cold and only loosen and tighten one bolt at a time. Torque is 60 ft lbs.

 

After milling the head did you check for timing chain stretch? and adjust?

 

A 'ticking' or rattling could also be a worn timing chain guide.

 

 

 

Where did the gaskets blow? In the same place? Could one of the bolt holes not been cleaned out and the bolt tightened up too soon?

[dvdswan]

I've always been told you should check your deck on the block when you have a head gasket blow.  did you have that checked?

[Sick720]

It sounds just like loose rocker arms, the guy that grinded the valves said that they were in bad shape and barely cleaned up. And I can rotate the outer springs when the valves are in place, is that normal. Lol I wouldn't think so. And the timing chain seems fine but I'll have to check it out. But it does have that hard miss at idle. Like something is up with the valve lash. I checked the block with a straight edge, and everything looked good. And it blee between cylinders three and four again. But I am hard on the truck, and I do have a Weber carb. And the white wire going to the distributor is unplugged, it runs like crap when it's plugged in. But other than the hard miss at idle it runs pretty good. And when downshifting it's not a clean smooth sound, more like a slight and quick backfire.

[dvdswan]

whats the white wire for on the dizzy?

[Sick720]

I believe it make ita dual fire, i may be wrong though.

[datzenmike]

The white wire will allow the dizzy to shut off the exhaust side plugs under certain conditions of heavy load. Disconnecting it just lets it run dual plug at all times. If it runs crappy with it on then maybe look at the intake side plugs. If forced to run on a single plug per cylinder maybe one is fouled or the plug wire is bad or the rotor is cracked?.

 

I can't being able to rotate the valve spring at all. There should be 115 pounds of pressure with the valve closed. Is it broken? Might explain the ticking. If it is, it's an easy fix without removing the head.

[Sick720]

Really, how? Through one of the ports? I don't think a valve is broke, I think they're sitting too far up in the seat. So the spring isn't keeping the pressure like it should. What do you think Mike? Sound like that could do it? Valve not closing right, floating a bit, that would give it the hard idle and the ticking sound. How does that sound???

[sick620]

sick720? what the hell!! I must have fans! :p

[elmerfudpucker]

What shape is the radiator? Get it boiled and flow checked to be sure, mine cost me about $130 for a rad and $75 for the heater core both from autozone, but this has been 2...3 years? Seems like if the temp gauge hits above the half mark a Z22/24 motor will pop a gasket...but anyway I stopped having issues once the rad, core and water pump got swapped out. I seem to remember mine popped between 3+ 4 as well.

[datzenmike]

Broken valve spring. There is an inner and outer spring. Take a really good look at the outer spring. Post some pictures.

[Sick720]

That guy just ground the valves, and left them in place. I put the springs on, all the valves and springs look good. They're just sitting pretty far up in the seat. So they're probably not holding the right pressure on the spring. And my radiator heater core are good. Lol a fan? Probably just had the same idea :p I want to get a custom license plate with sick720 :)

[datzenmike]

And I can rotate the outer springs when the valves are in place, is that normal.

 

Pretty sure they shouldn't be loose enough to turn by hand. How about some pictures?

[Sick720]

I'll pull the valve cover in a little while, how do you want them taken?

[datzenmike]

In focus.

[Sick720]

And all of the outer springs do rotate, i thought that it wasn't right.

[Sick720]

Alrighty, will do.

[Sick720]

Well you were right Mike, i can almost make it jump time by hand. Looks like the tensioner fell out >_<

[MicroMachinery]

Your title should be "Tensioner Challenged".

 

Too soon?

[datzenmike]

You're jumping around too much. You can check out the tensioner with a fleshlight looking down below the cam sprocket. What I want to know about are the valve springs being turned by hand. How is this even possible????

[MicroMachinery]

Fleshlight lulz

[datzenmike]

Forgot I turned the auto correct off....

[Sick720]

Well I can't see it and it has about an inch of play. So I'm assuming something ain't right in there. And the way i see it is, there's too much of the valve seat gone. Therefore the valve sits too far in the head, which would loosen up the valve springs. No?

[datzenmike]

It would have to be sunken a long way.

[Sick720]

Lol fleshlight