4 plug z24?

[Dean720Ada]

I'm just curious about something I've seen a couple pics of z24 motors with only 4 spark plugs. I know the dizzy is swapped to only run 4 plug specifically on the intake side. What I'm curious about is the exhaust side is just left open? or do you have to seal the spark plug ports? I know the z18et only came with 4 spark plugs. I seeneed couple pictures of converted efi z24 and a blow through turbo z24 both only have 4 spark plugs. so i just wanted to know what happens to the exhaust side,

[datzenmike]

I have a couple of single plug heads and the exhaust sides were never drilled out. If using dual plug head with only one plug the other side will need to be sealed. Just leave the old plugs in them.

 

You don't have to use a 4 plug distributor. You can run the eight plug and leave four wires off.

 

There is no advantage to a single plug head and dual plugs are a much better idea. Dual plugs shorten the burn time, so much less advance in needed.

[uberkevin]

That would be from a 200sx right?

[Spiff]

4plug heads are all over here in Europe. They got the 8plug heads as an emissions thing I believe, we didnt have the same requirements.

We had z20e engines in the 910 bluebird and 200sx, they where 4 plugs. We got some z24s engines in the d21 although most where diesel but the Z's where 4 plug. Some Z24i's where offered later and I believe they had 8 plug heads. So there is alot of mix and match over here.

Even the z18et I've seen with both 4 and 8 plug heads.

[Dean720Ada]

thanks Mike makes a lot of sense.The only 4 plug head I've seen is only the z18. I didn't know they made 4 plug heads for the z20,22,and 24. that's real interesting though. I've never even come across something like that on the net that the came stock with 4 plug head from the factory. but makes sense that they only have it Europe. or do they have it in Australia as well? are all NapZ heads interchangeable to fit z24 block?

[Dean720Ada]

Datzenmike how do you even come across a 4 plug head here in the US. did you get it imported here? or did some US spec cars Come with 4 plug heads.

[Lockleaf]

Early 200sx s110s came with a 4 plug head in the U.S. not sure out any other stuff did here

[datzenmike]

All Canadian Z20Es in the S110 200sx ('80-'81)had single plug heads. The later Z22E did get the 4 plug.

 

In the US '80 non California Z20E 200sx and Z20S (A10) had single and switched to dual for '81 and up .All California were dual plug. All Z20S Z22 carb in the 720s were dual plug..

[Spiff]

I think all heads can be interchanged, so you can put any Z head on any Z block.

[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.