Thanks to @Lumens, I was able to scan the 1973 TSB Nissan Publication.

An interesting TSB on the E88 head change for Feb 1973 shows a larger combustion chamber where the piston extends into.

The compression height of the piston is longer so that the piston's deck height is greater by 0.7mm.  If you need more "squish" on a 240z with E31 or early E88, seek out these pistons!

 

Or just shave the block deck. I’ve not measured a stock piston height on the 2.4 , but my ITM pistons were 0 decked compared to stock L28 being + .018

73 E88 = hemi-Z 

well--kinda/sorta???

Edited December 28, 20177 yr by Zup

I plan to put my numbers matching L24 back in the car. This I think will help to sell it.

In doing so I had the block bored out and fitted with .040 pistons. P/N 12010-H2716.

Not sure now if these are going to extend above the block deck.

I am also not sure what they mean by 'these items are not interchangeable.

Would those be the ones with the bigger rod bolts?  I bought a '73 motor just for the round tops and pleasantly surprised to find the later E88 head and the better rods, now maybe better pistons too.  Now to figure out what to do with all this mish mash of parts I have coming out the windows of my storage building. 

The 1973 pistons go higher above the block (deck height) which causes them to protrude further up into the chambers. They can collide with a head that is not open enough. A thicker head gasket may help.

You can see difference in E88 champers in these two pictures:

Pre 1973

1973 & 1974 (to accept protruding piston)

There also seems to be another later E88 from other markets with EFI. ( MR30 skylines) It is like a p90

 

25 minutes ago, Lumens said:

I plan to put my numbers matching L24 back in the car. This I think will help to sell it.

In doing so I had the block bored out and fitted with .040 pistons. P/N 12010-H2716.

Not sure now if these are going to extend above the block deck.

I am also not sure what they mean by 'these items are not interchangeable.

If you are concerned, you can always shave the pistons .010 inches or so. The crush on the stock head gasket is about .055 inches, so clearance should be adequate......I would think C/R should be bumped.....not the head lol......that's a good thing!

Only way to know for sure is to measure


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The head i planned to use is an E88 from a 260Z. It has been ported and shaved .020.

I still have the original 72 E88 head as well. I will dig out the pistons and measure.

12 hours ago, madkaw said:

Only way to know for sure is to measure


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What I meant as far as measure is to install a piston in the block on the crankshaft and measure the ‘pop out’ of the block. I would be surprised if any additional thickness of HG would be necessary .