The compression would be obviously low on that car maybe even lower with the SC crank which is a shorter stroke. However there are other things that go into the mix.

Someone mentioned a problem with wrist pin size. The wrist pins are about 1mm larger. My guess is that the busging could be bored out that much. or bore out the rod end a little to accept the larger bushing.

Cylinder heights are about 1mm different. The dome shape and placement of the wrist pin also effect CR.
The coating seems to kill the deal anyway.
It was worth a shot!

There's a scale on the lower right of all those EM photos. It might say 10 um, that's 10 microns.

I'm really stoked about this rebuild. I will be sealing up the case this weekend, my cams are on their way back from EBS (330 grind), I've got my heads back from the valve rebuild, and now it looks like these cylinders are going to cooperate. I've still got some painting and transmission work to finish, so it's looking like another month before it's all back together. So it'll be that long before we know if this reconditioning worked.

Is anybody else here thinking about trying this AN-30 polish (besides anh911)?

Ok, i know this thead has gone on for what seems eternity with enough information on ausil to write a doctorit on it. I just got my parts back yesterday, including the cylinders. I gave my old boss a call, who runs the shop, to give me the smack down on everything that was done.
In his exact words, this is what he had to say about the cylinders. "We measured the cylinders, they were in spec. We sent them out to this place that does a "special" type of honing that they call lapping. The process involves a silicon paste that's slightly acidic. The reason for the acid is so that the paste will take a small layer of aluminum off and the silicon will replace it. Therefore the piston rings actually ride on a microscopic layer of silicon, which came from the paste, and never contact the aluminum. Put plenty of oil on the rings when you reinsert them into the barrels and break-in should be no problem."
I haven't read through the entire thread and all the theories that were posted on ausil cylinders and how they are "freshened up". But from scimming through, what he tells me seems along the lines of what some others here have mentioned. If anyone likes, i can take a close up picture of one of the inside walls and post it, they looks kind of different compared to when they left.

1fastredsc,
I think they got it partially right, in that silicon paste is used...AN-30 from Sunnen. It does not contain any acid, but it does remove the aluminum of the bore through mechanical action using a felt honing device to re-expose the silicon particles that are dispersed throughout the substrate. However, (Rondinone can correct me if I'm wrong) the paste does nothing more than lap the surface and does not deposit any silicon back into the aluminum substrate. They are also correct in saying that the rings actually ride on the peaks of exposed silicon particles, never actually contacting the aluminum. I think however, if the car has lots of miles, the rings finally machine the silicon particles even with the aluminum surface, and as a result, a severe pitting of the bore occurs.

Rondinone,
I have made arrangements to purchase a (relatively) low mileage set of alusil P&C's, whihc I am planning to polish with AN-30. I figure for a couple hundred bucks, if they last 50,000 miles it'll be worth it. If I get more then it's gravy but at least I'll have seen it with my own two eyes and will just have to pony up for a reconditioned set....

R/
Dustin

Rondinone, I think you will be very sucessfull with the rings sealing properly. Considering the method I used, I am confidant.
Maybe it's time to consolidate the into. Maybe Wayne can post an article in the tech section. He could possibly put together a kit.
How much of the AN-30 did you use anyway? What did it cost?

Konish, I bet they will last longer. anyway by that time someone might have resolved the overbore piston avalibility problem.

I used about 1/5 of a 1 pound can, and I could have used much less. The total cost was about $32.50 for the paste and a few bucks for the felt. As of this weekend all six cylinders are polished, and the new rings and pistons are installed back in the cylinders.

If this works on my car, and a few other people are willing to try it on their cars also, maybe we could consider a tech article. Although I'm also confident that this is going to work, I'm a bit hesitant to recommend this to anybody else until we've tried on some willing guinea pigs. I'll have mine up and running in a month or less.

Konish, yes the AN-30 is only mechanical. When I started out on this epoch I was thinking about using some sort of acid etch, or electrochemical etch, but then decided on the polish because of it's availability and some control problems associated with etching (not to mention that it's used on the cayenne). It's possible that some shop has developed their own procedure that works based on an acidic polish. It's interesting that we've now heard of two shops that can recondition these cylinders. It would be nice to have that sort of information available to the rest of the community, for those who don't have an adventurous spirit.

1fastredsc,

Please post those pictures you mentioned. I'd like to see if they look anything like mine. Thanks,

Rondinone,
Not a bad price on the paste, you mentioned a few bucks for the felt.
What did you use in the end? Did you happen to price sunnen's portable hone and their felt pads?
Who supplied it to you?
I like your idea about posting info about shops that will do this as well.

Rondinone,
I well remember when we were going down the road of etching, but the upside of allowing that "free thought" brought us to where we are today. I think too, Jack (aka Snowman) offered up some ideas about the grape hone that we have quasi-confirmed but was intially thought of a heresy by the circles of elders. I would conisder myself a willing guinea pig...can't wait to give it a try. Of course you're right in saying that 1fastredsc's shop may use a acidic paste for etching as well as the mechincal lapping action of the silicon. However, I am still a little suspicious of claims that the paste re-deposits silicon particles of any significance to the surface. Also, as you mentioned I would think that using acid in the silicon mix would result in the same control problems you mentioned about controlled etching. Having said all that, I will say that I have no idea what I'm talking about, but I am willing to learn. When I do get my cylinders, I'll have them spec'd and proceed from there....:-)

R/
Dustin

The felt was actually a turtlewax miracle towel from Advance that was cut, doubled over and wrapped around the stones of a cheap engine hone. Real felt would probably work better in hindsight, because the miracle felt tore up a bit too easily. I never looked into the portable hone, but if I ever do this again I'll probably think about it.

The paste can be ordered directly from Sunnen. Here are two numbers from the order sheet, but I can't remember which one I called.

314-781-2100
1800-325-3670

The part number is just AN-30.

I posted a patent earlier in this thread that detailed an etching procedure from Daimler Benz. It contained a pretty good technical discussion on the problems associated with etching, and that really sealed it for me. Being that I'm a chemist, and not an engineer, I was sort of enamored with coming up with a chemical approach. But there are just too many things that could go wrong, especially with a cylinder wall that might have lots of little invisible pits.

When I first removed my cylinders I thought that they looked pretty good. After cleaning them up I noticed that two had some pitting that wasn't visible before. Etching them would have been a disaster.

You guys must excuse the blurryness of the pictures, my digi cam doesn't compensate for the fact that i don't hold it still enough i guess. Anyhow, here are some photos, i'll give the cylinder a second shot this week before i put them on with the heads and close up the motor.
http://forums.pelicanparts.com/uploa...1075784769.jpg http://forums.pelicanparts.com/uploa...1075784794.jpg http://forums.pelicanparts.com/uploa...1075784824.jpg http://forums.pelicanparts.com/uploa...1075785153.jpg

1fastredsc,
Would you mind telling us where your cylinders were sent to have them cleaned up? They look great!

Also, does anybody remember the reply to this thread about a small shop in Canada that did another set of Alusils...there was also a mention of the old timer doing a bunch of vega work too...not that I own a vega...no, really....

R/
Dustin

Dustin,

PBH was the one who mentioned the "old timer" in Toronto, Canada. You can email him at: harper "at" fhwelding.com

His replies are on pages 12, 13.

Ok, there's one pic with a flash and one without. Extra credit if you can figure out what book that is under the cylinder. Anyhow, the shop i sent my cylinders to i believe sent them out to someone else to have this done. So i don't know who did the work, but the shop that took care of it for me was PowerTech Porsche in Rockaway, NJ. Just to repeat what's already been stated about this, the more permanent fix for this is to switch over to nikasil cylinders. This is more for the financially challenged looking for a temporary fix until funds permitt more costly upgrades.
http://forums.pelicanparts.com/uploa...1075834922.jpg http://forums.pelicanparts.com/uploa...1075834945.jpg

That's Wayne's rebuild book.

Please send the Kinesis wheels I won to................. :D

I thought the topic mostly dispels the belief that the Alusils cannot be reused with confidence, unlike reusing a Nikasil cylinder? :confused: The big slam against the Alusil was the "rings won't seat" issue. The refreshed cylinders pictured on a microscopic level here look to be ready to seat some rings and not be a temporary solution. As long as the P's & C's are in spec., switching to Nikasil P's & C's seems like a waste of alot of money. That is, unless you're increasing displacement or changing pistons for cam, valve clearance, or induction system (or all of the above) issues.

Looks *slightly* familiar...

I haven't read this entire thread, but I do have some opinions. You can reuse the Alusils, but do so at your own risk. Just about every expert rebuilder I spoke with does not like Alusils on rebuilds because they sometimes will not seat new rings. I guess if you're rebuilding your own engine, and you can afford the time to tear it down again if the rings don't seat, then fine. I have also heard that the Alusils may wear out very quickly after a rebuild - but I have also heard the contrary too.

It would seem that Nikasil is the only *sure* bet, which is why I recommended this approach in the book. While I'm sure that you could use Alusils in a rebuild, you may want to rethink that if you don't have time to swap them out later on...

-Wayne

Wayne:
Some have been waiting for your opinions here. When you get the time I invite you to read the entire thread. There really is alot of factual based knowledge in it. I especially treasure the info we recieved from the cylinder manufacturer (KS) and Sunnen. They have both developed a procedure and endorse it by providing the materials to do it. I think with the recommended procedure the longevity after rebuild is most likely extended and the risk of ring seating failure is signaficantly reduced.

What is great here is that enthusiast community has come together and found some viable options where before little information was known.

Many are rethinking the "Nikasil is a sure bet" because of the reported experience within the BMW community.

Then again if I were an expert rebuilder I would most likely recommend new parts every time as opposed to reconditioned parts. In that situation my reputation, and the consideration of warrantee claims would be on the line. (I think I've said that before.)

Again, a quest was made for anyone to report problems they had with rings seating following a ring-job on Alusils. After the few month's life of this thread we have only herd sucess stories and no failures.
(Many of the sucess stories were with very unconventional methods because of the lack of knowledge we have today.)

Please read all the information and circulate it among your engine experts and I would love to here their comments.
I have no place or intention of challenging anyone's wisdom and especially the knowledge you have consolidated into you book which I believe is a tresure as well.

For those of us that can't afford new P&C's and want to extend the life of their engine we have an option based on facts. Your endorsement and or comments would mean a lot.

The reason i stated this is because the shop that i sent my stuff to, although stands behind this procedure for ausils, still doesn't like them. The vibe i'm getting is that from their experience ausil is just flat out inferior for the performance minded to nikasil. That vibe might be because they are all racers in that shop, and that's all they think about. If ausil is every bit as good as nikasil, well than maybe i'm wrong. I do know that when i have the funds, some 98mm nikasil barrels with some 8:1 compression JE pistons will be in my sites (and a garrett turbo to go along with it :D). But until then, if i can get 60k miles out of these ausils, i'll be happy.

Understood 1fastredsc.

Thanks for the clarification.

Wayne,

It's about time you chimed in. Excellent rebuild book, by the way.

My only question is: how many expert engine builders have tried the Sunnen procedure for refinishing high silicon aluminum? My own wrench had never heard of it (he's owned a porsche shop for 20 years).

The "Problem" the experts have is that they are changing someone bokoo big bucks to rebuild their engine for them. If you were the big bucks rebuilder "expert" would you
a. experiment and use something that might not work, give you a bad name, and make the customer unhappy?

b. Use the best materials and methods known to man to give your customer the best possible service and never have a comeback?

If you are not quite the stellar "expert" but want to maximize the bucks your shop makes, then you ALWAYS use brand new cylinders...etc Never give the customer a break even when possible. Are YOU going to re use these cylinders?

If you are selling parts, are YOU going to go out of your way to tell the customer to re use his old parts? (and NO Wayne is not the object of this comment, as it is a generality, and generalitys never apply to everyone).

The whole point is that it is not in the general best interests of the "EXPERTS" to even look into the question possed by this thread, consequently why should we be suprized to learn that they are not up to snuff on the subject. If you have read this carefully you will realize this is not a slam against "experts". Its only what rational people who are concerned about their business and reputation would do under the circumstances. IE ignore a risky, unknown, process with little likely hood of return.

This is the kind of thing the avid amateurs must pursue, but using true expertize.

I beg to differ snowman, the "experts" are there to make money, yes. But that doesn't mean reusing the old parts won't make them money. I'm sure that if the "experts" where more in tuned in our methods of avoiding $$$$$ charges they'd indulge. For example, this sunnen product must still be boughten from somewhere. If i were an "expert", i'd test the procedure then advertise it myself. Why? Because from the little i know, most shops make the most money from labor, not profit off of parts. And the procedure of lapping your cylinders from the way i understand it is mostly labor. Or someone like wayne can sell a felt tool to lap the cylinder, along with this AN-30 product you gentlemen speak of. Make sense.

I just edited out my own response as not relavent to this thread. its gone. I changed the last sentance and left it in.
suffice it to say I disagree with 1fastredsc.

I am especially suspicious about the talk about silicone deposition and etching. I frankly do not beleive it, my opinion. The information produced so far on this thread is probably much more accurate, and usefull.

Well, as it turns out I HAVE re-ringed my Alusils ;) The used Nikasils I purchased were well out of spec, & so I returned them for a refund. Given the information which has come out in this post, and putting my faith in the my Goetze colleague, I've rebuild my motor with new Goetze rings and just a quick wipe clean of the bores ie no special treatment. It will be a few weeks before the car's running but I'll keep you updated as to how it goes.
Fingers crossed!!

Nathan,
Just goes to show you just can't trust those junk Nikasil cylinders...everyone knows that they are basically a one-time use part anyway. ;-)
Wow, that was liberating...

R/
Dustin

This has been an incredible thread!! Sorry for my confusion but I wanted to ask for clarification what the concensus is:

1. The Nicasil cylinder is harder than the piston, and if it's still round you can put in new iron-coated aluminum pistons (sized individually to match) and Goetze phosphate-iron rings?

2. After honing with AN-30 and felt, the honing compound is left in the cylinder because it fills in the pits? A low speed is beter than high because it allows the felt to dig the aluminum between the silicone particles better?

3. Stone honing(even fine grit with oil) is too rough on the Nicasil surface because it creates undesired deep crosshatching? What about for overboring .30(or whatever the standard is) at a higher speed in a pressure wash solution so it cuts the top of the surface better, followed by fine finishing? Still a non-no?

4. Break in new engine using heavy loads so the outer ring material wears into the walls and creates a quasi-mist of iron coating similar to that of the rings/pistons? These are both relatively soft and hold oil and flex slightly to create a low drag surface after break-in?

Nice work gentlemen. I'm sure there more to come.

John,
I think you are confusing Nikasil coated cylinders and the Alusil cylinders that have been the subject of this entire thread. Nikasil cylinders do not require iron coated pistons...aluminum pistons are used. Also, the purpose of the iron coating on the pistons of Alusil cylinders is to prevent galling between the the cylinder and piston. Stone honing is possible with Alusil cylinders provided they are done by the method outlined by Sunnen and finished with AN-30.
AN-30 does NOT deposit anything on the surface of the cyls...it is simlply a lapping paste that cleans up the folded, distorted metal left behind by either the rings or by the honing process to re-expose the silicon particles within the aluminum substrate of the cyl. After the process the reminaing AN-30 compound is removed via parts washer, or simply wiped out. Basically, at a microscopic level, the silicon particles are left proud of the aluminum substrate of the cylinder...essentially forming islands of silicon particles. The piston (rings, actually) never actually touch the aluminum material of the cyl becasue they ride on the peaks of the silicon islands (see the profile graphs on earlier pages). Obviously, the rings will eventually wear the peaks down flat, and the contact between cyl and piston will cause pitting of the aluminum. Hopefully, if oversized pistons are sourced with the proper coating, the cyls could be overbored leaving a surface (after the proper procedure) similar if not exactly like the factory surface.
Again, the problem with overboring Alusil cyls at this time is that there aren't oversized pistons available with iron coating...but some Pelicans are looking into that as well. With any luck a manufacturer will realize that most folks rebuilding SC's and Carreras using Alusils would jump at the opportunity to reuse their old cyls and buy new, over-sized, higher-compression pistons...simply by taking an exisitng product (ie aluminum piston) and coating it with the ferro-coat and tin.
I'm not sure what you mean by the last statement, but ideally the silicon particles would stay exposed forever and not get clogged by the ring material. From what I understand, the randonly dispersed silicon crystals exposed on the cyl wall provide and ideal surface for oil to accumulate in the "wells" between the silicon peaks....like an ocean surrounding a thousand little islands. When the area between the peaks begins to accumulate ring material and piston material, I would think that the wear at this pint would rise dramatically....near the end of the cylinders life expectancy...say 200,000 miles :-)

R/
Dustin

Nathan,

300 posts and the best you can do is a quick wipe?

Just kidding. How many miles were on your cylinders?


John,

I'll answer #2, because that's the only one I know anything about. I'm also going to yammer on in summary of what we've learned.

There isn't yet a real consensus about anything, but what we have done here is to dig up a bunch of info about alusils. Some of the most important information includes:

1. Alusils are a high-silicon aluminum eutectic. The silicon particles are formed in the casting process, as the aluminum-silicon mixture cools and the silicon solubility in the aluminum decreases. The silicon particles precipitate in the aluminum just like rock candy does in cooling water. The silicon is not put there afterwards like it is with nikasil (spit). Hence, the silicon particles are present everywhere in the cylinder casting. The silicon particles were originally exposed by etching back the aluminum after machining the bore. The exposed silicon particles provide a wear surface for the rings. There is no direct aluminum-ring contact, or at least there shouldn't be.

2. KS still produces alusil blocks for the Cayenne, and some mercedes and bmw engines. Rather than chemically etching the aluminum back as before, they now use a procedure developed by sunnen. A very helpful KS engineer seems to think that the cylinders can be reconditioned pretty easily. So did a certain phone rep at Sunnen.

3. Sunnen also markets it's procedure and all the parts necessary to carry it out. Others have posted both the procedure instructions and the relevant catalog page numbers in this thread. The most important part of the procedure is the use of AN-30. Although there is silicon in the AN-30, it's there only as an abrasive, because it matches the hardness of the silicon in the alusil. It's like drilling hardened steel with a hardened steel bit. You won't get very far. But you can drill aluminum with a hardened bit.

4. Some reckless types on this board have tried to recreate the sunnen procedure at home using a cheap spring-loaded engine hone wrapped in felt, plus AN-30. According to some measurements posted earlier, it seems that about 8 minutes of polishing at 100 rpm was adequate. The sunnen procedure calls for 2 minutes, but that's with much beefier equipment. A good indicator for the home job seemed to be the shiny area around bdc. When it started to take on a bit of texture, the rest of the cylinder was ready. It feels like a real fine chalkboard, btw. You can even screetch your fingernails.

5. Some electron micrographs were posted earlier in an attempt to understand how alusil behaves. Those were taken of a very worn cylinder (220k), so there was alot of pitting. Although the polishing compound could be left behind in pits, that's not the intention. Highly pitted cylinders would be poor candidates for a rering anyway. (on edit: Jerry StGermaine's contribution of a used cylinder was very important to this endeavor. It provided practice plus information, which resulted in the confidence to try out the AN-30 on my own cylinders).

My cylinders were slightly pitted in #2 and #5. One interesting note was that the pits were not clearly visible when the cylinders were first removed. After polishing they were obvious. One might ask if the polishing caused the pitting. Maybe, but unlikely. I think they were filled with oil when first removed. When they were oiled for assembly the pits became less obvious.

I just finished the longblock today. Hopefully we'll be starting it up in a few weeks or so.

If you listen to cartalk on npr, some guy called in this week and asked about #4, i.e. break in easily like the factory says or run it hard to seat the rings. Click and Clack said follow the factory procedure. With alusil, there is a compacted debris layer that forms, but I don't really know enough about it to say anything intelligent. I'll probably follow the original factory break in, because I believe that I have recreated the factory cylinder finish. We'll see, won't we?

Great re-cap guys.
It's getting hard to add anything useful except wish Nathan, Rondinone and other's well on their rebuilds. Keep us posted!
Next continue urging Anh911 on his quest for oversized coated pistons.
Any news?
I'm not usually in to this but what about a name for this quest?
Th Myth-buster theme has run it's course. I would say case closed.
We got SCWDP but that's another story and leaves out the Carrerra guys.
I also am intrested in keeping the thread alive as we seem to be in intermission until something new comes up. (Lobby music is playing in my head.)

BTW 3600 miles on my Scotch Brite job today and getting smoother and stronger! It's supposed top be a balmy 45 in D.C. Today!

Rondinone, my cyls have done approx 79k. See my earlier post regarding surface finish. I had mine checked and were within spec for a new cylinder, hence the "quick wipe". I figure if it works, we'll all be laughing, if not, I'll just have to blag another set of Goetze rings from work and start again!!

My bet is that you will be fine!
Good luck!

Bump. Sorry about the typo with the two cylinder materials, plus an idea.
When washing out the AN-30, use a baking soda/basic oil-based wash so it neutralizes(for a day or two) the acid residue in the pits. Is rust neutral Ph?

I think AN-30 is neutral, ie not acidic and therefore dosen't require anything but plenty of washing with hot water with a little Tide laundry detergent, original formula, mixed in, a good stiff bristle brush and a very good rinse. (note don't forget to wipe down the cylinder with a fine coat of oil after cleaning to prevent rust). Can this be confirmed with the Material Safety Data Sheet?

It is a bit hard to get good photos of the surface, but I have two shots that seem ok.

My cylinders were done witht the Sunnen method on a Sunnen machine (by the old-timer who used to do Vega's, the car not the city).

Can someone post higher res pictures? Mine are way too big...

I sent them to Jeremy but he has not replied....

Yes, Jack, AN-30 is not acidic. It's made up of oil, sodium stearate (emulsifier) and the silicon. I cleaned my cylinders by wiping them with mineral spirits, then acetone, then a good hosing with brake cleaner.

Rust is a mix of iron oxides and iron hydroxides, depending on the conditions under which it forms. pH is a measure of proton concentration in solution. It's calculated as -log(proton concentration), so low values indicate higher proton concentration. Acids are solutions of high proton concentration, or low pH. Although rust can be dissolved by low pH, and is more quickly formed at high pH, it's not considered acidic or basic. Laundry detergents, bleach, and most cleaners tend to be higher pH, while naval jelly and soap scum remover are lower pH.

Thank You.

Rondinone et al,
Quick question. I just bought a set of Alusils (P's and C's) which are reported to have 108k miles on them. The bores look fairly fresh...not anything like the pitted experimental cyl that Rondinone sacrificed at the Alusil altar. However, I have noticed lateral scratches on every cyl (save one) that are not only shiny in appearance compared to the rest of the cyl, but are easily detectable with my fingernail. For some reason I just don't remember this type of scratching on other cars I have rebuilt, but to be fair, they were water cooled VW's, and I don't think I scrutinized them very hard. The scratches are consistent with the movement of the rings (along the paralell plane of the piston travel) and are perfectly paralell to each other around the circumference of the bore. One is particulalry bad...the scratch runs the entire length of the cyl for the entire piston path...almost looks like a perfect manfacturing seam. I would assume that some of this is normal (since it occured on every cyl to different degrees), but if prepped with the Sunnen method, should the scratches cause that much of a problem for ring seating? I'm not overly concerned becasue they were really purchased for two reasons: experimentation and to act as a stop gap measure until I can REALLY build the motor I want...say when I retire :-) Are scratches more indicative of a motor that let go a bearing (or some other nasty piece) and the resultant material getting trapped under the rings to cuase them. I was a little dismayed when the box they arrived in was from Motor Meister...but the cyls were in a Mahle box (lol)...dude I bought them from built his motor with FRESH Mahle P&C's, that must have been painful on the old back pocket. At any rate, I'd like to hear any and all thought on this matter if y'all would be so kind...Jack, Rondinone, PBH WIlliam Miller...calling all believers...

R/
Dustin

I think that if you can feel it with your fingernail it needs to go. Either with local polishing eg scotch-brite (short term fix) or Sunnen method (long term fix?).

Mine had scratches in some of them. One was pretty long and deep, like you stated I could feel it with my fingernail. My guess was that at some point a piece of dirt (something hard) caused this. You have to be very careful (Clean) while the inside of the cylinder is exposed to the elements. I think that's part of the reason why Wayne recommends not even taking the pistons out.

Cylinder #4 had no noticable dammage from the broken ring. My guess is because the ring material is softer than the silicon. The broken ring was worn like a mushroom shape on the edge that meets the cylinder.

I wonder if some of the smaller scratches could be from silicon particles
comming loose from the cylinder wall. They are probably too small to see.

Anyway most or the scratches were gone after scotch brite hone. Only the one being notable.

For me this was a budget rebuild to extend the life of the engine.
Luckily the expensive parts were in spec. So, the bottom end is fresh as well as the heads. (New valves, guides, springs.) I ported out the intake side of the heads to match the larger Euro intake runners.)
My P&C's were in spec except for the one noted scratch.

So I am good to go for a while I hope. 10,20,---50K I don't know.
Hopefully anh911 finds someone to supply the oversized coated pistions before I need to do it again.
I plan to do a leakdown, and valve adjust the next time I change the oil. Within a month or two. I will report my results. I don't have a good comparison in terms of performance because the fuel injection was bastardized from the time I bought the car. I finally found a rebuilt Euro fuel distributer that solved 99% of the problems. I think the last 1% is will be resolved when I have some time to spend on dialing in the CIS.

Off Topic Rant:
This may be true for most K-basic CIS but as the car warms up there is a period of time where the cold running compensation components (Auxilliary Air Valve & Control Pressure regulatior) have warmed up to their normal warm running positions and the engine has not reached it's normal operating tempatures. This creates a lean condition until the engine temp catches up. This is only causing a rough idle for 5-10 minutes. (Longer on colder days and shorter on wamer days.) Anyway I need to run it a little rich to compensate.

I bought a new control pressure regulator and the system pressure and the control pressure are dead on the high end of the specifications.
My guess is that when the Fuel distributer was flowed it was done at a slightly higher control pressure. I may need to raise mine up a bit but I hate to open up an new part. Off idle it is always on the rich side probably a little too rich.
I am currently tuning with an analog A/F meter.

Sorry to divert, but we have some pretty good problem solvers here. I'll start another thread if anyone wants to follow.



It's plenty rich on initial warm up.

My cylinders had light scratching also, although I don't believe that any scratches were really that deep. After reconditioning I don't recall any scratches being left behind, but they may have been masked by the added texture.

Check your ring lands. The bad cylinder may have suffered from a broken ring.

Barring a problem with the ring lands, I probably wouldn't worry about it. Can you post a picture?