We just acquired a 1973 240z with a 280z engine installed in it. I do not know the year of the engine. I have found numbers on the engine such as "N33" and "L28 563932" below the rear spark plug. Does the L28 mean it is a 2.8 liter? How can I tell what year the engine is, and what does N33 mean? The spark plugs are set to .038 but I think they may need to be .040 or greater. I noticed the distributor has two plates with numbers and marks. Does that mean you can set the timing without a timing light?

Edited November 27, 201114 yr by derbyD

L28 is a 2.8 . N33 is the head type. You have to use a timing light to set the timing, it's on the crank pulley .

There is no "N33" head, that may have been something you saw on the intake casting. The head casting number is on the bottom of the head, by the #1 and #2 spark plugs. The block casting number is on the left side, below the manifolds.

If it is a 280Z engine, then the block casting should be "N42" which came with either an N42 or N47 head. However, mix-and-match possibilities are endless so you won't know what you have until you verify it.

The plates in the distributor are for "phasing" the two pick up coils (for electronic ignition, maybe for dual points in a 240Z also), if they're installed. You still need to use a timing light to set timing.

Besides the N42 block, you could also have an F54 block, and/or a P79 or P90 head. The casting numbers are in the same spots though.

Is the engine set up for carbs or did they transplant the EFI? And the distributor might be electronic or points. That would determine what your plug gap should be.

Pictures are always good, for you and the viewers.

The block is a F54 with a P 90 head. The distributor is electric and it has duel carbs. I'll work on posting pix.

Edited November 28, 201114 yr by derbyD

The block is a F54 with a P 90 head. The distributor is electric and it has duel carbs. I'll work on posting pix.

This means that you have a late 280ZX long block. The P90 only came on the turbocharged cars. You can confirm that the bottom end is from a turbo by looking through a spark plug hole with the piston at TDC. If it's dished, then it's a turbo block, if flat then NA. FWIW, the turbo engines have a compression ratio around 7.4:1.

There is no "N33" head, that may have been something you saw on the intake casting.

I wouldn't be so sure..

http://zhome.com/ZCMnL/tech/128combo.html

If that isn't enough, Carl Beck makes reference to the N33 on several older posts. Maybe it's a myth, but not necessarily.

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Edited November 28, 201114 yr by sblake01
Post was based on unclear/confusing info....

N33 is on the intake

I wouldn't be so sure..

http://zhome.com/ZCMnL/tech/128combo.html

If that isn't enough, Carl Beck makes reference to the N33 on several older posts. Maybe it's a myth, but not necessarily.

Nope, there is no head casting with 'N33' on it. It looks like they came up with alternative names for the 3 variations of the E88: small chamber, large chamber, and large chamber plus bigger exhaust valve. Again, there is no such thing as an N33 head casting.

N33 is on the intake

Just as I thought.

I've seen P90A heads on non-turbo cars in the local wrecking yards. I don't know how they got there, or what pistons were in the F54 block, but the P79 and P90 heads have the same combustion chamber volume, so if you have flat top pistons, you would be around 8.8 CR, like the stock NA F54/P79 setup. As LeonV suggests, check through the spark plug hole with a strong light to see what you have.