New/ reman head

[stuart720]

I realize this question was just asked not long ago but there wasn't an answer provided. So I blew a head gasket pulled the head and realized I had a crack between the valves on cylinder 3. Does anybody know where to get good, complete new or remand heads

 

[720_Jeff]

On 4/14/2023 at 11:05 AM, datzenmike said:

What year 720. (should put this in your profile it saves a lot of questions later)

 

I'll start this off with the quote from datzenmike above.  

 

Next, I'd suggest following the thread directly below this one, or it is at this moment.

There is at least one other head thread in recent days/weeks, so I'd work my way through those threads and probably refine the question.

 

 

 

[stuart720]

85,2wd,z24. Miles unknown, odometer stopped 15 years ago

 

That sure is a lot of information about z heads and all but, na my question still stands. 

 

I have a cracked head. Toast. From valve to valve in cylinder 3.

 

I'm asking if anyone knows of a reputable someone that sells refurbished/remanufactured that are complete with cam and all.

[datzenmike]

It tells me that you want a Z24 head and not the earlier Z20 or Z22 head. They will work but the Z24 head is best.

 

 

Check out the local wrecking yards.

[720_Jeff]

Oh crap, didn't realize until rereading the thread I referred you to, that it wasn't the thread about z24 head sources.  That thread, is directly below the thread I did refer you to.

There's a ton of information here, search is your friend.

 

Think that thread answers the question, where to get new or reman heads.  eBay is another source.  Seems like new/reman is $500+, junkyards would be considerably cheaper, but probably in unknown condition.

 

[stuart720]

So I ended up finding one on eBay on a flash deal kinda thing. Thought it was a good deal till I got it. So I'm assuming it's off an Aussie import, has a little kangaroo above the 10w stamp. It only has 4 spark plugs, where mine is the normal 8. Will this head still work?

[datzenmike]

It will work on single plug but you must increase the ignition timing to 10-12 degrees BTDC to compensate for this. If you have smog inspection it very well may not pass.

 

 

You're in Idaho, there must be wrecking yards there?????

[stuart720]

Smog disappears in June around here, so that's ok. Will this effect engine performance? I assume not since they ran them in foreign countries.

 

Yes there's wrecking yards but these trucks are fairly scarce around here. And when you find one it's either trashed or picked clean

[datzenmike]

It won't run any better. Dual plugs reduce emissions and improve the thermal efficiency slightly. Just wondering if the intake ports are round or square with rounded corners. 

[stuart720]

They are rounded squares

[datzenmike]

Good that was used exclusively on the Z24. Both style will fit but this is best.

[stuart720]

So will I be able to run the head with only 4 plugs without any issues?

[Stoffregen Motorsports]

1 hour ago, stuart720 said:

So will I be able to run the head with only 4 plugs without any issues?

In the old days (when people were still p[laying around with the Z motors, trying to make horsepower) the 4 plug head was preferred, but to maximize the performance, distributor and cam timing tweaks were also done, not to mention carburetion and exhaust.

[stuart720]

Yea I'm not trying to build this for the track or anything, it's been a great work truck for the last 12 years and I would just like to get it back to that point.

 

So advance the timing to 10-12 degrees and maybe a carb tune and I'm good?

[datzenmike]

 

 

14 hours ago, datzenmike said:

It won't run any better. Dual plugs reduce emissions and improve the thermal efficiency slightly. Just wondering if the intake ports are round or square with rounded corners. 

 

4 hours ago, datzenmike said:

Good that was used exclusively on the Z24. Both style will fit but this is best.

 

Yes it will work. Dual would be best but single will work just fine.

[stuart720]

Id prefer the dual plug, but I can't seem to find a decent one for a decent price. I suppose I'll slap it on and see what happens 

[stuart720]

So I couldn't bring myself to use that head, can't find a decent priced one anywhere.

 

Does anybody have one they'd like to sell?

[Madkaw]

I’ve been running my Z24 head with and without . Hard to say what’s better , but the 8 plug might just runner better . I’m testing timing and fuel octane to see what’s best MPG . I’m fuel injected so that makes a difference also 

[datzenmike]

With single plug you need a longer lead time to get all the fuel burned and maximum cylinder pressure at that sweet spot of around 17 degrees after TDC. Earlier, and the crank throw, rod, and piston are close to vertical and the piston not easily moved against this. Too late and the expanding gasses are chasing the rapidly accelerating piston as it goes down the cylinder. To achieve this, the timing would be around 10-12 degrees. With a dual plug head the burn time is much shorter. Because there are two points of ignition the timing can be much less advanced. Timing on a dual plug is about 3 degrees.

 

The effect is about the same but on the earlier ignition the heat produced has more time to be absorbed by the cylinder walls (piston is still down the cylinder) and combustion chamber. On the dual plug much more of the heat of combustion is available to expand and push down on the piston. The real reason for the NAPS dual plug is there is less time for nitrogen to combine with oxygen at peak cylinder temperatures.