Z24 COLD valve adjustment

[JoeR]

Last time I adjusted the valves in my truck, it was a pain to get all the adjustments done in time. I would prefer to adjust the valves while the engine is cold. Does anyone know the COLD valve specs? Much obliged...

[datzenmike]

A cold adjustment assumes the clearances will be close when the parts heat up and expand. I would use a cold adjustment only if the head was just assembled and only for start so it can warm up.

 

You want to get them set before it cools down too much? That's easy.Mark the timing notch on the back of the pulley with chalk or crayon so it is easy to find. Loosen plug leads from the plastic looms on loosened valve cover and warm engine normally.  Remove the two coil high tension leads.

 

Hot engine...

Remove valve cover and crank engine so that the #1 cylinder valves are closed, find the timing mark on the crank pulley and align it with the ZERO mark on the ignition timing scale. You are now at Top Dead Center on #1. Valves 1 and 2 are closed cam lobes downward. There are eight (8) valves. Set the following valve lash to 0.013"...

 

Adjust 1, 2, 4, 6

 

Turn engine ONE complete revolution and set timing mark to ZERO. Valves 1 and 2 should be part open with cam lobes somewhat upward. Set the following valves to 0.012"...

 

Adjust 3, 5, 7, 8

 

Done, and it was fast. Have everything ready in advance. At TDC 1, 2, 4, and 6 valves are closed. One turn later 3, 5, 7 and 8 are closed.

[crimsoneclipse]

.008 intake .009 exhaust (cold)

[sheph]

On 7/26/2014 at 9:17 AM, crimsoneclipse said:

.008 intake .009 exhaust (cold)

Wouldn't the cold values be greater?

[datzenmike]

Z24 HOT lash is actually 0.012" for intake and exhaust. This is right out of the '84 FSM.

 

 

On 7/26/2014 at 8:17 AM, crimsoneclipse said:

.008 intake .009 exhaust (cold)

 

25 minutes ago, sheph said:

Wouldn't the cold values be greater?

 

I would have thought so but.... The '73 620 FSM lists L series engines cold as 0.008" intake and 0.010" exhaust. HOT is 0.010" intake and 0.012" exhaust.  They generally change 0.002" between cold and hot. Try setting them to 0.010" and then warm the engine and confirm that they opened top 0.012" and see.

 

I like the hot setting as that's the the factory recommendation. No ambiguity there. Hot is hot or what ever the engine is when fully warmed. Cold could be anything depending on the outside temperature -20 to 110F. Cold assumes the clearances will change and become the required 0.013". Why not just set it hot and be done with it?

 

 

[captain720]

I consider a cold setting on a Z24 only for a freshly rebuilt cylinder head before an initial warm up. Just do it warm, if you park in a garage it will cool off slower for winter adjusting. I made a video on the adjustment procedure as well if that's helpful.