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Rebuild Nissan Engine Z20s


morfeas

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  • 2 weeks later...

[/url]">http://20141226_121742_zps7bee113f.jpg

I'm rebuilding the engine because it sounds piston pounding the valve and concluded that it has eaten the bearing connecting rod, as well in the past has happened before.

 

This is the number #3 cylinder?

If repaired before, it probably wasn't done correctly. The crankshaft bearing surface will (likely) need to be turned down to true it up again. Then a smaller size bearing used on a new rod.

 

When done, the clearance between the crankshaft and the new bearing should be between 0.001" and 0.0022" or 0.025mm to 0.055mm.

 

 

 

 

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The crankshaft surface must be flat and smooth just like the one with the white tape on it.
 
20141226_121700_zpsd958bda5.jpg
 
If not smooth it will grind up a new bearing. The surface must be ground down to a known undersize and an undersize bearing used. The space between the crankshaft and the bearing is very critical
 
 

When done, the clearance between the crankshaft and the new bearing should be between 0.001" and 0.0022" or 0.025mm to 0.055mm.


This is about the thickness of a sheet of paper!!!

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Congratulations on finding out how to post pictures! There are all to many folks who have been on here for a long time who have yet to read the instructions on how to post pictures that will work on this site. It looks like you have alot of work to do, but listen to Datsun Mike! You will rebuild this engine!

 

Best of luck!

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Another option is to replace the crankshaft,if there is another one around?

 

 

I want your opinion about the engine block.

 

20141226_115818_zpsb0621f97.jpg

 

M2 casting, late 70s early 80s L20B and Z20 block. Small amount of erosion around the head bolt and coolant passages, seen worse,but gasket should seal ok.

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Congratulations on finding out how to post pictures! There are all to many folks who have been on here for a long time who have yet to read the instructions on how to post pictures that will work on this site. It looks like you have alot of work to do, but listen to Datsun Mike! You will rebuild this engine!

 

Best of luck! 

Thanks MikeRL411.

Yes, I have a lot of work to do and I need your help to rebuild this engine!

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Pics helped a lot, get the crankshaft reground, while the crank is at the machine shop, bring them your rods and have the big end re-sized with NEW rod bolts.

 

Listen to Mike, he has way more patience than I do.

ok,

 

Another option is to replace the crankshaft,if there is another one around?

it sounds good advice! 

at the new crankshaft what points I will notice?

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Z 20 -Can someone please post if these are stock pistons or after market ,they have four valve reliefs for a four valve head ,was in a 200sx usdm model ,I was told it had 60k when I bought it so I always thought was stock .I will post build with L series head on Alleycatgarage in other than Datsun projects , .

Welcome aboard and hope we can help you from Greece keep posting !100_2613-1.jpg100_2634.jpg

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ok,

 

it sounds good advice! 

at the new crankshaft what points I will notice?

 

A replacement crankshaft will have (or should have) perfectly smooth main and rod bearing surfaces for new bearings to ride on.

 

The width of the crankshaft main bearing journal should be 59.952mm to 59.955mm.

The rod bearing journal should be 49.961mm to 49.974mm Measure in two places and at 90 degrees to them. This will show any taper or oval.

 

 

Z 20 -Can someone please post if these are stock pistons or after market 100_2613-1.jpg

They appear to be stock Z20 pistons

 

motorpistonsL20BZ20EZ22SZ24007La-1.jpg

 

............................Z24.....................................Z22......................................Z20E................................. L20B

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