720World

Little Trucks, Big World

The Napz Series Engine Family, Identification, Comparisons, Differences, and Verification

Starting this thread in an attempt to provide information on the similarities and differences in these engines, and also verify specifications, wall and deck thicknesses, bore, stroke, piston pin heights, rod lengths, and any other specifications, etc...

 

This spawned from PlumCrazy's (James) cracked Z24 block issues.

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Replies to This Discussion

From discussion http://720world.ning.com/forum/topics/z24-cracked-block?id=2016119%...

 

This is an old thread, but after reading through it again I got to thinking...  Why don't we all work together to verify some of the things we've heard and read over the years, like how thick the top plate is on a Z24 or Z22???  I'm sure Plumcrazy has a few Z24 blocks he wouldn't mind cutting one up lol.. (Sorry James).  And, if someone has an old Z22 block that's destined for the junk yard anyway, maybe we can take a grinder to it and find out what's really under there!!!  Maybe we can verify the Z22S/E cylinder wall differences too, and BTW, how do you tell a Z22S from a Z22E block, without knowing what vehicle it came in????

Well I'm going to try to resurrect this old thread with no replies...  And link it to this thread http://720world.com/forum/topics/z24-cracked-block?id=2016119%3ATop...

I'm working on a new project which has led me to examine the left side of my Z22 and Z24 blocks a little more closely than I've ever done in the past and I noticed something new to me...

Some Z22 blocks have more mounting holes in the area of the air conditioner mounting bracket than others.  Some of my Z22 blocks are tapped and drilled for 7 holes in that location, and that area of the block is reinforced with extra "webbing"...

I am thinking this reinforcement would probably result in a much more rigid and stronger block.  Whereas all my Z24 blocks are drilled and tapped for only four holes, and lack this webbing.  However I do also have one Z22 block that is also drilled and tapped for only 4 holes, and lacks the webbing reinforcement...

I'm thinking this is one of the unspoken differences between the Z22S vs Z22E, or early vs. late Z22E?  Anyone take notice of this?

The top 2 pics above I believe are Z22S motors and have a 7 hole pattern with ribs (I haven't documented the casting numbers yet).  The bottom photo above is a Z22E motor, and it has 4 holes with ribs...   The air conditioner bracket only requires 4 bolt holes, so I'm not sure what the center two, or the top center holes of the group of 7 might have been used for?  Are these simply hold-overs from the L20B engines?  It certainly appears so...  https://www.californiadatsun.com/long-block-short-block-engines/dat....  So were Z22S blocks simply bored over L20B blocks???  It very well could be since...

Z22S (stroke/2)+connecting rod+ piston pin height = 227.4
piston deck height: -0.05 mm (below block)

L20B (stroke/2)+connecting rod+ piston pin height = 227.0mm
piston deck height: -0.45mm (below block) 

So if that explains why there's 7 holes in the Z22S block, then what were the 7 bolt holes for in the L20B block???  It appears the 620 A/C bracket only used 5 bolts, but may explain the lone top bolt hole.

I'm not sure what else may have bolted into that location, air injection pump???...

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