Jesters LZ Build

[Jester]

My poor little L16 is slowly trying to go to Datto heaven. (I'm sure it exists) I can't afford to go the route I want, which is a VG, right now. Sometimes it sucks being the only income. But, I feel it's a worthy sacrifice to have my wife home with my kids. A few months ago I picked up a free '81 Z22 from a 720. It has one piston that is fubar. Number 3 cylinder is in need of a bore job because of this. Crank/Rod journals are beautiful. So, I am thinking of building myself an LZ 2.3 and possibly reworking a 280Z intake and fuel injecting it.

 

Now that my idea is out there, here is the question I have for the 720 guys; what is the difference between the '83-'85 and the '86-'89 Z24 pistons? I have looked around on ebay and rockauto to get an idea of some prices and noticed that they list two different applications. I want to make sure I order the right ones.

If I do build this thing I will keep this thread going. It may be slow going either way.

[yello620]

About time you started this.

[wayno]

Datzenmike will chime in here with the answers I am sure, I didn't know there was more than one type of Z24 piston, as the machine shop just ordered in a stock dished Z24 piston, and that is what is in my LZ23, which is supposed to be an 8.9 to 1 CR with a W53 head.

[Sealik]

Knew you were up to something...saw you lurking in some LZ builds :D

 

I believe there is no difference in Z24/Z24i pistons...all years

[datzenmike]

I too assumed.

 

From 07 '84 the piston and ring part numbers change. This different piston is also used in the D21 Z24i motor. The Z24i piston skirt is about 4mm longer and the ring end gaps are larger than the earlier Z24. That's about it.

 

I would suspect that if you want to use earlier pistons in a Z24i just use the earlier rings to match.

[Sealik]

I too assumed.

 

From 07 '84 the piston and ring part numbers change. This different piston is also used in the D21 Z24i motor. The Z24i piston skirt is about 4mm longer and the ring end gaps are larger than the earlier Z24. That's about it.

 

I would suspect that if you want to use earlier pistons in a Z24i just use the earlier rings to match.

 

I stand corrected.........again :D

 

I forgot to mention there are 2 different sets of rings for 'Z24' (89mm) pistons.

The NPR Z24/Z24i pistons and rings I'm using have a 2mm (top) 1.5mm (2nd)....and a 4mm oil ring

Other Z24 rings are....1.5/1.5/4mm

Most manufacturers carry both options...1.5 or 2 mm top ring....relative to piston used

 

http://www.ebay.ca/itm/Nissan-2-4L-SOHC-New-NPR-Pistons-Rings-Z24-Z24i-/370463434689?pt=Motors_Car_Truck_Parts_Accessories&hash=item56415767c1

 

These have the 1.5 top ring

[Jester]

Wonder why they added another 4mm to the skirt? Doug, did you get yours at DNJ. I'm thinking that sounds like a better way to go as long as the land between the top and middle ring is still the same size. These are also being sold on Rock Auto. I believe these are the same brand of pistons that NKL DYM is using for his LZ 24 build.

 

Spent some time in the garage tonight with the boy teaching him how to cut the end off a tap to make it a bottoming tap. Then we proceeded to hit EVERY hole in the block with a counter sink to knock the edge off when we were done. Once I get some pistons in my hands, I'll take the block into Hatch Engine for some boring. The purple Chevy in the second row is NKL DYM's old drag car.

 

 

[Sealik]

Wonder why they added another 4mm to the skirt? Doug, did you get yours at DNJ. I'm thinking that sounds like a better way to go as long as the land between the top and middle ring is still the same size. These are also being sold on Rock Auto. I believe these are the same brand of pistons that NKL DYM is using for his LZ 24 build.

 

Spent some time in the garage tonight with the boy teaching him how to cut the end off a tap to make it a bottoming tap. Then we proceeded to hit EVERY hole in the block with a counter sink to knock the edge off when we were done. Once I get some pistons in my hands, I'll take the block into Hatch Engine for some boring. The purple Chevy in the second row is NKL DYM's old drag car.

 

Maybe they extended the skirt to compensate for a thicker top ring....?

No clue.

I noticed all Z24 pistons at DNJ have the 2mm ring.

I purchased 'these'.. http://www.ebay.ca/i...=item56415767c1 ...but with a 2mm top ring, and then bought a "P" plain cast iron ring set from Hastings....rings shall seat easier.

Note... the letters in any piston and or piston ring set.. denote ring material.

 

P....plain cast iron

C....chrome

S...chrome steel

M...moly

[datzenmike]

Maybe they extended the skirt to compensate for a thicker top ring....?

No clue.

I noticed all Z24 pistons at DNJ have the 2mm ring.

I purchased 'these'.. http://www.ebay.ca/i...=item56415767c1 ...but with a 2mm top ring, and then bought a "P" plain cast iron ring set from Hastings....rings shall seat easier.

Note... the letters in any piston and or piston ring set.. denote ring material.

 

P....plain cast iron

C....chrome

S...chrome steel

M...moly

 

The change almost coincides with the switch to throttle body injection (Z24i) Wonder if that's why? and why?

[Jester]

Doing some more reading this morning on the subject of piston skirt length, I found an article on a forum. The concern these guys had was in dealing with piston skirt length in a short deck hight stroker motor. The discussion was based around the amount of skirt dropping bellow the bottom of the bore, allowing the piston to be tilted slightly. Upon traveling back up to the top, it will rub off some material each time. The common fix for this problem in their racing application was to bevel the bottom of the cylinder liner slightly allowing room for the piston to dance before complete reentry. Being that I'm not building a stroker and that my max rod angle will be at 18.3 degrees, I think I will be just fine.

Now with Nissan adding an additional 4mm to the skirt length, I wonder if the final length of the bore is 4mm longer on the '86 and up Z24's?

 

EDIT: Heading off to the yard to pick up an N42 Z car intake.

[Jester]

I wasn't able to get the intake. Someone beat me to it. I did find a '84 200SX with a CA20. I pulled the harness for the EFI and the computer. Also found an A87 closed chamber head that has the notches for the injectors. I had to stash it for another day. I didn't have the $50 to spend on it.

[RadioRedline]

I have sent PM.

 

Radio

[510rob]

Make sure that the piston wrist pin bore is the size you need for your rods - it may have changed from 21mm to 22mm. Just sayin'...

 

Also, if the piston skirts are too deep, then stick the pistons top down on a mill with a clamp through the wrist pin, and zing a few millimeters off them to suit. It takes minutes to do. Just sayin'...

[Z-train]

So, I am thinking of building myself an LZ 2.3 and possibly reworking a 280Z intake and fuel injecting it.

This is what i did and doing right now.

[Sealik]

I might be tempted to go EFI also....but....just have some SUs 'lying about'.... ;)

They do look pretty cool... :D

 

 

Also....

Z22 connecting rods are about 2mm wider than the Z24s

Z24 rod/piston has about 3 mill (total) clearance.

 

Some Z22 rod/Z24 'piston' combos have about .012 clearance....not good....small end of rod should be shaved

My block is now back at the machinists.... :blink:...poop

[Jester]

So it was the small end of the rod that was the issue? I don't understand why no body else has run into this yet.

 

Z; Do you have a build thread going on this?

[Z-train]

No/yes/sorta.I have some topics some where about the engine build,but not the FI thing.The manifolds is at my fabricators place and i'll be calling him to boot him in the ass in the A.M.

 

One thing to keep in mind is that the 280 manifold runners are about 31 MM,they are SMALLER than a L-20B manifold( i think they are 35mm).Now,since my motor resides in a daily use/cruiser,the motor was built with priority on low end(port velvocity) grunt.THe cam selected is all done by 5500,which is fine for MY purpose.My torque figures went up 60%.It may not work for you.So,the million dollar question is:Where does the 280 manifold start restricting airflow?

[Sealik]

So it was the small end of the rod that was the issue? I don't understand why no body else has run into this yet.

 

 

Possible issues with other LZ23 builds..???..just haven't reared yet?

Or the clearance is within tolerances relative to the aftermarket piston used.

I do know mine were 'a little' too tight with the NPRs

[Z-train]

Possible issues with other LZ23 builds..???..just haven't reared yet?

Or the clearance is within tolerances relative to the aftermarket piston used.

I do know mine were 'a little' too tight with the NPRs

Aftermarket slugs were used.

[Jester]

What brand of pistons did you use Z?

[Z-train]

They came from Rebello-i lost all the paperwork on the motor,so i have no cam specs or slug info.

[Jester]

I know someone that has Rebello do his engines. Maybe he knows what he uses.