Z20 4 plug head on a Z24

[Charlie69]

Is it possible to run a Z20 4 plug head on an 8 plug Z24?

[datzenmike]

There is no advantage to doing this, and only if your Z24 head is bad and all you have is a single plug head handy until you can get a replacement. Just remove the four not used plug wires from your distributor cap and dial in some more advance like 12 -14 BTDC. Single plug will definitely need more advance.

[Charlie69]

You are right Mike I have a bad Z24 head and all I have is a Z20 head.

[datzenmike]

There were two different combustion chamber sizes, one with a much higher compression but I believe they were only dual plug. The early non California S110 and the A10 heads should be 57cc same as the Z24.

[Charlie69]

Thank you Mike.  After I heal up from knee replacement I will play with this some but if you recommend just getting another Z24 head I will go that direction.

[datzenmike]

Well, I would rather have the dual plug head myself. If you have a stock Z24 it handles the EGR better with a dual plug. More spark with more EGR. If it runs poorly just disconnect the EGR. You will have to advance the timing. 3  with dual plug and 10+? with single.

[Lockleaf]

I would actually consider swapping to a 4 plug head if i find a complete Z series fuel injection setup to go with it.

 

Only purpose being to make the engine bay look cleaner. I'm not a power engine builder, so any possible power loss wouldn't much matter to me and I would likely delete the egr system for engine bay cleanliness as well.

[Spiff]

Z20 heads have smaller intake runners compared to the z24, so you loose some in the higher revrange. Also they have round intake ports instead of square so if you put your 24 manifold on the 20 head; not good for flow.

[datzenmike]

You can but the Z20S from the '83-'86 Mileage Option 720 has smaller combustion chambers. Used on a Z24 this bumps the compression to near 9.5, stock is 8.4. I suspect this 'smaller' head was used on the Z18ET engine because of it's lower displacement.

 

Z20 and Z22 heads have round intake port and manifolds. Z24s have a square with rounder corners intake and ports. The Z20/22 heads also have EFI injector notches, the Z24 head does not.

 

Top Z24, bottom Z20/22. The Z24 does not have provision for the mechanical fuel pump.

 

 

 

Z20 Mileage option head. Smaller combustion chambers with two small quench areas the regular heads do not have.

[Charlie69]

Mike I also have a complete Z24I engine that is locked up.  I have been told the the distributor and timing covers are different.  I was saving this engine to rebuild and put a 4 speed automatic out of an 86 Hardbody.

 

I do not know what year the engine is or what it is out of except that it was supposed to be a truck.

 

Is there a way to tell what the engine came out of from the engine serial #?

[datzenmike]

The Z24i were only ever used in the very late 720 the D21 Hardbody, the WD21 Pathfinder and the short lived Vanette.

 

The Z24i used a CAS (crank angle sensor) The timing cover is different for the CAS mount and the oil/CAS drive spindle is also different.

 

Don't know about the engine ID. Maybe from the oil pan used?