LZ22 Piston Ring Source and maybe a machine shop

[Crashtd420]

You making me second guess what I'm gonna say.... 

If stock bores are 87mm then wouldn't .25 over be too small for the piston I believe the .25 adds to diameter.... by what you said the bore is 87.6.... even the .5 might not be enough.... 

And I believe the piston rings would be specific to the over sized piston... 

 

Also Be careful how you view the numbers.... 

You said .025 or. 050... 

It in mm so .25mm or .50mm

Which equals .010 or .020.... 

 

So if your bore is 87.6 = 3.449

And 87.5 = 3.445....  

Not sure but you might be looking at more than a quick hone....

Don't order ring before someone smarter than me chimes in....

[Stoffregen Motorsports]

L motors used good quality iron in the blocks, so ridges in the bores are not very common.

 

When measuring the bores, the cylinder diameter is the important measurement. Using a digital caliper is fine for measuring bores to order rings, but not for checking piston to wall clearance. That needs to be done with a bore gauge and micrometer.

 

As Crash mentioned, measure in either inches or millimeters, not both.

 

87mm in inches is 3.425"

.010 over is 3.435"

.020 over is 3.445"

etc...

 

Just to clarify, there are no markings on the piston tops? Nothing? Did you clean them to see under the carbon?

.

[mojojojo78]

Sorry for the confusion. My cylinders are 87.6mm or 3.449". The hastings rings only come in .010", .025", .050" oversize.

I only had telescoping gauges and my caliper available to measure the cylinder bores.

I have not cleaned the top of the pistons yet.

It looks like the pistons are the stock ones. What is an acceptable clearance? Should the pistons be slightly larger to fit the bore? Its hard to tell in the pictures, but there looks to be a good amount of clearance between the piston and cylinder wall.

[Crashtd420]

19 minutes ago, mojojojo78 said:

Sorry for the confusion. My cylinders are 87.6mm or 3.449". The hastings rings only come in .010", .025", .050" oversize.

I only had telescoping gauges and my caliper available to measure the cylinder bores.

I have not cleaned the top of the pistons yet.

It looks like the pistons are the stock ones. What is an acceptable clearance? Should the pistons be slightly larger to fit the bore? Its hard to tell in the pictures, but there looks to be a good amount of clearance between the piston and cylinder wall.

Those piston can not be stock if your bores at 87.6mm.... 

Oversize rings have to go with an oversize piston.... 

You cant put 87.5 rings on a piston designed for an 87mm piston rings.... 

I'm not 100% sure but I believe piston to wall clearance is generally only about .002 to .004.... but that was from a quick search...

 

[Stoffregen Motorsports]

1 hour ago, mojojojo78 said:

Sorry for the confusion. My cylinders are 87.6mm or 3.449". The hastings rings only come in .010", .025", .050" oversize.

I only had telescoping gauges and my caliper available to measure the cylinder bores.

I have not cleaned the top of the pistons yet.

It looks like the pistons are the stock ones. What is an acceptable clearance? Should the pistons be slightly larger to fit the bore? Its hard to tell in the pictures, but there looks to be a good amount of clearance between the piston and cylinder wall.

Read again. That's not .025" and .050", that's .25mm and .50mm.

 

[Stoffregen Motorsports]

Piston to wall clearance can be as little as .002" but more commonly around.0035". I've run them with as much as .010", but that's waaaaay over the limit and will not last long.

 

It depends on the kind of piston, but generally, cast pistons in older engines (not modern) run around .003" as new. Rebuild clearances can be looser.

[Crashtd420]

14 minutes ago, Stoffregen Motorsports said:

Piston to wall clearance can be as little as .002" but more commonly around.0035". I've run them with as much as .010", but that's waaaaay over the limit and will not last long.

 

It depends on the kind of piston, but generally, cast pistons in older engines (not modern) run around .003" as new. Rebuild clearances can be looser.

So would an 87.5 pistons be put into an 87.6 hole? 

That is .004 clearance.... 

If this is correct you might be ok with a hone and re ring with the .5mm oversize rings

Edited February 6, 2023 by Crashtd420

[mojojojo78]

Thanks for all the information.

I still need to pull the pistons to do some measuring and inspection on the rings.

[datzenmike]

2 hours ago, mojojojo78 said:

....  Both were 87.6mm +/-.05mm. I checked at the bottom right at the face of the piston and then at the top below the ridge. Then I checked the ridge and it was around 87.58mm +/-.05mm.

 

The max allowable wear on the Z22 cylinder bore is 87.050mm. If 87.58 at the top above the rings then this has been over bored 0.2mm before or your measuring device is out of calibration. Stock Z22 cylinder bore is 87mm to 87.05mm and stock pistons range 86.985mm-87.050mm selecting the proper piston and matching to the bore size will produce a piston to bore clearance of 0.025mm to 0.045mm or 0.001" to 0.0018".

 

The largest standard piston diameter 87.050mm in your 87.58mm measured bore produces a piston to wall clearance of 0.53mm or 0.020"!!!!! that ten times larger!!!! Like I said the next over size is 0.200mm then 0.5mm and then 1.0mm. Pull the pistons and measure their diameter they may already be 0.200mm over size.

 

If over boring find 0.5mm or 1.0 mm, if possible bore to the largest size 1.0mm or 88mm pistons.

 

 

 

 

 

2 hours ago, mojojojo78 said:

I just checked the Hastings website and only the 6149 and the 2M6149 are available in .025 oversize (6149010 / 2M6149010).

https://hastings.apacatalog.com/Home/partdetail/382

https://hastings.apacatalog.com/Home/partdetail/232

Which one would be better?

Or should I get the next size up? .050 oversize?

 

[Stoffregen Motorsports]

1 hour ago, datzenmike said:

 

The max allowable wear on the Z22 cylinder bore is 87.050mm. If 87.58 at the top above the rings then this has been over bored 0.2mm before or your measuring device is out of calibration. Stock Z22 cylinder bore is 87mm to 87.05mm and stock pistons range 86.985mm-87.050mm selecting the proper piston and matching to the bore size will produce a piston to bore clearance of 0.025mm to 0.045mm or 0.001" to 0.0018".

 

The largest standard piston diameter 87.050mm in your 87.58mm measured bore produces a piston to wall clearance of 0.53mm or 0.020"!!!!! that ten times larger!!!! Like I said the next over size is 0.200mm then 0.5mm and then 1.0mm. Pull the pistons and measure their diameter they may already be 0.200mm over size.

 

If over boring find 0.5mm or 1.0 mm, if possible bore to the largest size 1.0mm or 88mm pistons.

 

 

 

 

 

 

 

2 hours ago, Crashtd420 said:

So would an 87.5 pistons be put into an 87.6 hole? 

That is .004 clearance.... 

If this is correct you might be ok with a hone and re ring with the .5mm oversize rings

.004" is good.

 

1 hour ago, datzenmike said:

 

The max allowable wear on the Z22 cylinder bore is 87.050mm. If 87.58 at the top above the rings then this has been over bored 0.2mm before or your measuring device is out of calibration. Stock Z22 cylinder bore is 87mm to 87.05mm and stock pistons range 86.985mm-87.050mm selecting the proper piston and matching to the bore size will produce a piston to bore clearance of 0.025mm to 0.045mm or 0.001" to 0.0018".

 

The largest standard piston diameter 87.050mm in your 87.58mm measured bore produces a piston to wall clearance of 0.53mm or 0.020"!!!!! that ten times larger!!!! Like I said the next over size is 0.200mm then 0.5mm and then 1.0mm. Pull the pistons and measure their diameter they may already be 0.200mm over size.

 

If over boring find 0.5mm or 1.0 mm, if possible bore to the largest size 1.0mm or 88mm pistons.

 

 

 

 

 

 

We're all assuming it's been bored already.

[datzenmike]

5 hours ago, mojojojo78 said:

I just checked the Hastings website and only the 6149 and the 2M6149 are available in .025 oversize (6149010 / 2M6149010).

https://hastings.apacatalog.com/Home/partdetail/382

https://hastings.apacatalog.com/Home/partdetail/232

Which one would be better?

Or should I get the next size up? .050 oversize?

 inches and mm.

 

0.5mm is 0.197" Your bore is 87.58mm so just over 0.5mm over stock bore. Pull pistons and measure them. They should fit with 0.001" to 0.018" clearance. Your worn bore is wider at 87.6mm. No telling what replacement pistons were used... Nissan metric or after market inches. Nissan come in 0.2mm, 0.5mm and 1.0mm over size. After market are likely 0.025" and 0.050"

[Stoffregen Motorsports]

Piston manufacturers don't arbitrarily pick oversize dimensions. They stick to the .010", .020". 030" or .25mm, .50mm, 1.0mm scales. They wouldn't make a .025" piston or a .050" piston.

 

.010" oversize = .25mm

.020" oversize = .50mm

.040" oversize = 1.0mm

 

Machinists then measure the piston and bore/hone the cylinder to the correct size for the correct piston to wall clearance.

[mojojojo78]

On 2/6/2023 at 10:21 AM, Stoffregen Motorsports said:

Piston to wall clearance can be as little as .002" but more commonly around.0035". I've run them with as much as .010", but that's waaaaay over the limit and will not last long.

 

It depends on the kind of piston, but generally, cast pistons in older engines (not modern) run around .003" as new. Rebuild clearances can be looser.

So I did a quick check and it looks like I have .010" - .015" clearance all around the piston.

Is my best bet to get oversize pistons and rings and have the bore machined out for those pistons?

Or would it be okay to get .020" (.50mm) oversize pistons and rings and clean and rehone the block as is? 87.5mm piston in a 87.6mm bore. That leaves about .002" clearance between piston and cylinder wall. Honing might increase the bore like an extra .002" maybe.

Also, is there a difference in the pistons used for the 720 vs the 200SX? The 720 looked like it had more of a dish than the 200SX.

[datzenmike]

Piston to wall clearance should be 0.001" to 0.018" What you have measured is 10X what it should be. I'm confused with all your measurements so just try to fine 1mm over size (88mm) pistons for 720 Z22 and let the machine shop do the measuring and the boring. Specify a finish for chrome rings.

 

All 720 Z22 pistons are the same. This same piston was also used in the '81-'82 S110 200sx, BUT in Jan '82 this was changed to a piston with shorter pin height. Dish volume* is unknown but the rings are the same. This later Z22 piston will NOT work on the earlier car or the 720 Z22 engines.

 

There was no high compression Z22, so the two different pistons are probably going to be very close in dish volume.

 

 

[mojojojo78]

Thanks for that clarification. The 200SX I saw with the 2.2L was an 83.

[datzenmike]

The '83 model begins in July of '82, the previous year. Although the piston change is early in the new year it is really about half way through the model year. The build date of the car is likely on the drivers door or door jam.

[Stoffregen Motorsports]

9 hours ago, mojojojo78 said:

So I did a quick check and it looks like I have .010" - .015" clearance all around the piston.

Is my best bet to get oversize pistons and rings and have the bore machined out for those pistons?

Or would it be okay to get .020" (.50mm) oversize pistons and rings and clean and rehone the block as is? 87.5mm piston in a 87.6mm bore. That leaves about .002" clearance between piston and cylinder wall. Honing might increase the bore like an extra .002" maybe.

Also, is there a difference in the pistons used for the 720 vs the 200SX? The 720 looked like it had more of a dish than the 200SX.

We are getting ahead of ourselves.

 

The measurement of the bore is...? Using digital calipers or a calibrated bore gauge.

 

You found markings on the tops of the pistons? Or not?

 

If the bores look and feel ok (with your fingertip and fingernail), there is no way in hell the bore is worn to the point of needing a re-bore or another oversize piston.

 

With the numbers you've given us, it feels like we're having some difficulty with the difference between metric and standard measurements. So let;s clarify the actual measurements before proceeding. Decimal points are important.

Edited February 9, 2023 by Stoffregen Motorsports

[docbainey]

Also, make sure to measure the pistons in the correct spot

See below

[mojojojo78]

That is some helpful information. Thank you Doc.

[mojojojo78]

So I have been really lazy and have only worked on my car when I didn't feel lazy. Finally last night I got the oil pan off and pulled all 4 pistons.

#1 is okay

#2 has broken ring landings

#3 has broken ring landings

#4 has a broken skirt

I was able to find the correct pistons and I just test fit one last night and it went in snug. My caliper broke so I couldn't verify the diameters.

Anyways here are some pictures of the messed up pistons:

What is the best way to get the pin out? They are pressed in and I don't want to mess up my rods.

That chunk missing from the skirt had to have been missing for a while. I didn't see any metal chunks in the oil pan and nothing fell out when I pulled the piston.

The other two with the broken ring landings just fell right out.

All the damage is on the passenger side of the block. Does anyone think this could be caused by the fact that the coolant holes are missing on the Z22 block?

Edited August 8, 2023 by mojojojo78

[datzenmike]

The right or passenger side is the major thrust side on a clockwise turning crankshaft. Pistons are offset slightly on the pin/rod to help counteract this. Any chance the pistons were installed 180 with the notches to the rear?

 

Broken rings/ring lands would indicate that the ring end gaps were set too small and not allowing for heat expansion. Or was the engine over heated?

 

There were two different pistons for the Z22. Truck and 'early' S110 200sx car and later S110 200sx car. Check the center of pin hole to piston top. Truck/early should be 35.5mm and later pistons 32..1mm for use on a longer rod. Measure the old ones to be sure the new ones are a match.

[mojojojo78]

The engine did overheat twice. On hot days it would run hot. After putting in aftermarket gauges it would get up to 220-230F. It was never low on coolant though.

I didn't see any notches on the old pistons. My new ones do have a notch. I will compare them when I get home.

[Stoffregen Motorsports]

Broken ring lands indicate too much timing or too high compression ratio. Pinging can be cause by too much timing, and you can usually hear that, but high RPM detonation, from a timing curve that's messed up, you can't always hear that.

 

FWIW - 10:1 is totally fine, so I doubt it was CR that broke the ring lands. Too much CR usually cracks the top of the piston.

 

You need a pin press to remove the pistons. Installing is tricky too. Get the rods too hot and you can crystalize the metal. Too cold and the pin will grab before it's ion all the way. I heat with an oxy/acetylene torch and get the rods blue. It's what I call chasing the ghost. You'll see a shadow form around the flame. Once you see that, it's hot enough.

 

The pin fit in the piston should be verified before you try to install them. Lube up with light oil and work them back and forth in the pistons a few times. This will kncok down any burrs.

 

Sometimes new pistons come with a dot instead of the notch, indicating the front of the piston.

[datzenmike]

You can put the pins in the freezer also.

 

I used a press used for concrete testing. My pins took between 1,300-1,550 pounds to press out.

[Stoffregen Motorsports]

If you get the pins part way in, and not all the way, before the rod cools, it's a bitch to get them centered. Using a pin press on new pistons isn't ideal.

 

I should also add, use a rosebud style torch, not a cutting torch.