Does anyone know the differences in the year spark plugs? I'm putting a new motor and head in my 91 xj and nobody knows the year of the motor. It's a high output and a newer head than my original.

 

Below is a spark plug application chart.



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You can determine which cylinder head you have by looking at the left side of the head; the head casting number will be a four digit number cast on to the head. In this pic it is a 0331 casting number.



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Casting numbers:


1986-1990 = 2686
1991-1995 = 7120
1996-1999 = 0630
2000-2001 = 0331


The date of manufacture and casting number of the cylinder block is cast on the left lower side of the block.



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Other data pertaining to build date:



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I use NGK ZFR5Ns in all years.

 

Plugs should be gapped to .035". My 97 uses Champions. Had Bosch in it when i bought it. Factory said Champions, so thats what i use. Some dont like Champions, some do. Some dont like NGK, some do. Etc, etc.

 

Nobody doesn't like NGK.......

 

What Cruiser said
Both times

 

you are amazing. Thank you

 

Here is my spark plug chart:

ZFR5N.

 

ROFL!

 

The year of this block?

 

gotta pull the engine to read it...!

 

Can't determine the year from your photo, but the casting number looks like 8933002665 which is 1987-1990 vintage.


Refer to my post where it shows build date info on the right side of the block.

 

Which years had the chain on the block?

 

it is a renix era engine. Do you think it would be possible to use this head until I rebuild my high output one? I have a 91 which is the high output setup but I'd like to do the head right before installing.

 

If you are talking about using a 91-95 (casting number 7120) head on the 87-90 block, it may work, but....you'll need a 91-95 exhaust manifold and a 91-95 intake manifold. The 7120 cylinder head exhaust ports defer from the 2686 exhaust ports and I think the intake ports are different as well. You may even need different fuel injectors.


Are you sure you want to do this?