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LZ22 Piston Ring Source and maybe a machine shop


mojojojo78

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Over the past week my car had been smoking a lot. It was blowing smoke out of the breather on the valve cover. For the past few weeks I had noticed an excessive vibration when the engine was under load. It only happened if I was in 5th and accelerating around 4K RPM. If I accelerated slowly I didn't get the knock. So I thought there was just something loose on the engine. I couldn't find anything.

On Saturday I decided I should check my valves. I had been meaning to for a while. I adjusted them to .007-.008 on intake and .009-.010 on exhaust. I had seen those numbers in a few posts so I went with them. I then did a compression test and was very disappointed and bummed out.

#1 cylinder - 180 PSI

#2 cylinder - 100 PSI

#3 cylinder - 120 PSI

#4 cylinder - 180 PSI

I poured a little oil into #2 and #3 and rechecked the compression. Both cylinders shot up to around 220 PSI.

So I figure I at a minimum need new rings. I still need to start taking the engine apart to see if there is any additional damage to the cylinders and pistons. I am worried that the sound I was hearing was rod knock.

My plan is to try and do everything with the engine in the car for now. I don't have a hoist or a stand. I need to do all my steering linkage, so I can remove all that and probably the front cross member. Then I can drop the pan to get to the rod bolts.

I just don't know where to get a good quality set of rings from. And if I need to get the cylinder cleaned out where to take my engine too.

Anyone have any recommendations for the OC area in California? It would be nice and convenient if there was someplace close to Brea, CA. But I can transport the engine.

Whats a good source for the rings and maybe pistons?

 

 

1972 Datsun 510-Engine 26.jpg

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Local engine machine shop. There has to be one near you, and they can source the parts for the motor for you. They have access to parts that aren't easily found online.

 

For your type of rebuild, I would suggest Hastings "sprayed chrome" rings. They break in fast, but are better than standard cast rings. I'd stay away from chromoly rings as they can take forever to break in.

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220 PSI????? Just how much oil did you pour in????

 

Low adjacent cylinders could simply be the head gasket is blown between them. 2&3 is common as head warpage is maximum in the middle. Not saying your head is warped but check this when head is off. I think you'll simply find the gasket is blown here.

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So I was finally able to pull the head off. The cylinders look fine. The head gasket was fine. No signs of any damage. Could the rings have prematurely worn out and lost their sealing capability? I am going to measure the cylinder bores tonight for any wear with telescoping gauges.

I really didn't want to tear the engine apart any more, but I think I am going to have to pull the pistons to verify any damage.

What do you guys think?

I felt the bores and I didn't feel any deep grooves. There wasn't even a ridge at the top.

The guy I bought it from said that it had been rebuilt a couple years before and he barely drove it. Could it have not been properly broken in and the cylinders got glazed?

Also, I saw another posting about the Z block with the L head and there was talk about coolant passages. So on the passenger side there are 8 holes (2 per cylinder) on the L head but not on the Z block. Since I have the head off, should I drill these out? Will that help with cooling?

Pistons 02.jpg

Pistons 03.jpg

Pistons 04.jpg

Cylinder Head-Valves 01.jpg

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Lots of hone marks on the cylinders so probably was rebuilt.

 

I don't understand the 100 and 120 compression on 2 and 3 nor the 220 readings. An open chamber head on a 2.2 liter displacement would be a 9.84 compression ratio. 180 seems very good. If the 220 is wrong then maybe the others are too??? Perhaps the valve seats and faces are bad? 

 

Head is off. Have you checked to see if the head is warped? I would pull the valves and lap them by hand. This will give a good indication if the seats are alright.

 

Cylinders may have too aggressive a hone and it's unknown what rings were used. If chrome then the cylinder has to be perfect and the cylinder finish a certain way. For home made rebuild that does not include over boring and perfect cylinder finish a softer cast iron ring should be used so they break in quickly. Chrome rings can wear out before the bores smooth out.

 

Measure the bores. If stock 87mm then this was a home made 'hone and ring' job. If over bored there's no excuse for the rings to not be sealing. I think this is stock bore so pop the pistons out, re-hone and replace the rings with cast iron ones that seat in faster.

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Maybe the valves were tight when you were doing the compression test? Everything looks good. The bores, the hone, the color on the piston tops, and in the chambers.

 

???

 

Maybe #3 has a lighter color and that flaking off of carbon could be a sign of using coolant.

 

Check the block for cracks around the head bolt holes.

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I haven't had a chance to check the cylinder head for warping. I will do that after work. Same with any damage to the block as far as cracks or any surface irregularities.

My car had been running hotter than normal, like in the 190-210 range. Could that have been burning off the oil?

I am guessing that this is a home made hone and ring job as DatzenMike put it. The pistons look like the stock ones and I didn't see any stampings on them like Stoffregen mentioned that might indicate they were over size.

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1 hour ago, Stoffregen Motorsports said:

Maybe the valves were tight when you were doing the compression test?

 

 

Said he set valves in first post before the compression test.

 

Running at 190 is fine 210 is a little hot. Big question is was it using coolant and did it need topping up all the time. An unexplained loss of coolant could be a blown gasket but not severely so. Head may have slight warp and some compression leaking between the #2 and #3 but not as obvious as a severely blown out gasket. In the early stages. 

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Likely blow by. You said it ran hot. Maybe owner (not you) ran it too hot and the rings are broken... fits. The fix is take the pistons out and see. New rings but ring lands may also be broken too.

 

 

 

Pistons 02.jpg

Not all the holes in the block and the head are used. Find someone with an L20B and see what ones are used. You may need to drill out some coolant holes in the block. I think there are more holes on the spark plug side on an L series engine. The Z series head has 4 coolant passages out of the spark plug side where the L series does not so it needs more holes up into the head.

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Yeah, I saw another topic about this configuration. There are 8 holes (2 per cylinder) on the spark plug side that are on the L series head and not on the Z22 block.

There are 7 holes missing where the red arrows are. Would drilling these out to 1/4" help with over heating issues?

Z22E Engine Block Coolant Passages.jpg

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It probably will.

 

The L20B and the Z22 blocks are basically the same. The Z head has an outlet under each of the four intake ports on the right side because it's a cross flow head, so there is circulation of coolant out of the head on this side. The L series head needs flow up out of the block on the right side to push the stagnant coolant away from this side.   

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I wasn't able to check the head surface on either the block or the head yet.

I have been looking for the Hastings piston rings and it seems no one seems to have them in stock. What is a good source that will actually be able to get them? Is there another brand that will work as good or maybe better?

I checked Napa, O'Reillys, Autozone, Amazon and eBay. Even Rockauto says that they are out. I can find some unknown brands, but I don't want to do this again in 10K miles.

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I wouldn't worry about drilling out those holes. They newer design forces the coolant to the back of the block first then it circulates to the front through the cylinder head.

 

Overheating can cause broken rings, but not usually broken ring lands. That's usually from too much timing. A broken ring can damage the cylinder walls, with deep scratching that can't be honed out. The cylinders in the pics looked pretty good, but there is some scratching, though not the kind that make me suspect a broken ring.

 

The blow-by out of the valve cover is weird, and I would have guessed that pulling the head would have revealed more. Keep digging.

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Don't buy parts until its torn down and measured except gaskets, any decent shop should be able to help find parts.

Those scratches look like what you get when rings are not filed to remove burrs before installing and the gaps are all in one location, too uniform to be debris with more than 1 cylinder having the same pattern.

Edited by Ooph!
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I finally checked the bores and surfaces yesterday. Both the head and block were nice and straight with my straightedge. I didn't see any thing that would indicate warping. I only checked the center two pistons. 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. I can't even tell there is a ridge there by feeling it. So my plan is to remove the pistons and check out the rings. Do a light hone to clean up the walls a little. Replace the rings if necessary and hope for the best. If the rings are bad, I was going to order the Hastings 2C6149010 from the list that Stoffregen posted. I figured the .025 oversize is what I need. Hopefully I can get them. Everyplace I have looked at says they are out of stock. Summit Racing says it is a special order from the vendor.

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