'75 280z - Head temp sensor question

[Neb]

Quick (hopefully) electrical question:

My temp sensor (the one on the block below the #5 spark plug, picture below) is disconnect and I can't seem to locate the plug for it.  I will continue searching, but in the meantime, does anyone know if this sensor is an input to the EFI system, or does it go to the dash gauge, or what?  I ran my EFI bible checks and the temp sensor check came back ok, so I'm assuming that one is the one up in the thermostat area..

Thanks,

Ben

[rcb280z]

It is part of the ZX EFI. What engine do you have, F54? Or just a different head? Your temp sensor is located in the thermostat housing. Thats why you can't find a plug to the one in question. 

I wouldn't worry about it, just leave it in there.

Edited March 28, 2018 by rcb280z

[Neb]

Oh wow.. Well its not the original engine, I know that much.  Somewhere along the line it was swapped, but it wasn't me.  I had figured it was from another 280z.  If its a ZX block, are there other differences I need to be aware of?  I'll look at the number on the block tonight and see if that sheds an light on where it came from..

[rcb280z]

Look at the block and head numbers and post them here when you have them. I just saw your other thread "trying to set timing" . Curious on what you find out for an engine combo. Hope you find out before I leave out on my cruise to the Caribbean otherwise I'll have to wait til I get back stateside to read what you found out.

[Zed Head]

The Maxima L24E head also uses a CHTS, on a head ID'ed as N47.  It can get confusing.  Engine size should be stamped on that flat spot right there under the CHTS.  The block type will be cast in, not stamped, somewhere around the driver's side motor mount.  I always have a hard time finding the cast numbers.

[rcb280z]

Oh yeah, forgot about the Maxima head.

[Neb]

Took a couple pictures of the head and block.  Head says N47, block is L28 431708.  I think I grabbed the wrong number off the block though.. its supposed to be by the motor mount you say?

[Zed Head]

Yes, the block type number is by the driver's side motor mount.  It will be either F54 or N42.

But, it's looking like you have the MN47 head, as people like to call it.  A smaller combustion chamber, giving higher compression ratio.  But also smaller valves.  More endless discussion about pros and cons...

The 280ZX heads with the CHTS are P79 or P90, not N47.

[rcb280z]

4 minutes ago, Zed Head said:

More endless discussion about pros and cons...

Isn't that the truth. 

I'm going to guess N42 for the block....oil pressure sensor looks to have a single wire running to it.

Edited March 28, 2018 by rcb280z

[Neb]

I'll try to grab a picture of that casting mark on the block here in a couple hours.  This work stuff keeps messing with my Z time..

Assuming N42 block, N47 head.. this thing isn't going to explode right? 

Thanks again for the information.  Yall are great

[Dave WM]

Z engines are tough, you are not going explode anything.

[EuroDat]

I wonder what the PO did with the head, if he did anything too it. It's most likely bolted onto a N42 block. The head was designed for an L24 in the 1984 Maxima with the smaller valves and smaller chamber.

Chambers in the N47 are 44.6cc and in the MN47 they are 39cc. The N42 block also had dished (10.9cc) pistons. The F54 has flat tops and the P79 head had 53.6cc chambers.

The MN47 head on an F54 block would have a really high CR.