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I had this block reworked up the street by a small machine shop that is attached to an independence auto shop, both have great reviews. There were a fair number of aluminum I-4 heads sitting around when I went in so I figured my needs for a stock rebuild should be no issue. After picking the block up and reading about MLS headgasket surface roughness requirements I'm a little concerned...

There were a few bits of gall that had re-embedded in the aluminum that I got picked off with a razor but there are also some fairly deep hairline scratches in the aluminum that are distinguishable with fingernail. Out of curiosity I took a piece of 400grit wet/dry on a pane of glass and ran it over the deck a few times, careful to manage even pressure/strokes/direction. Certain areas between cylinders but still in the "shadow" of the liners smoothed out with other areas being untouched. Note that my thinnest feeler gauge sill wont pass under a straight edge. The liners are perfectly smooth, it's almost like a bit of the liner on the trailing edge of the cut broke off and gouged the aluminum as it was dragged by the cutter.

So am I being reasonable or neurotic? Again this build isn't intended to do anything but beat around on the street with barely over factory power numbers.

Thanks,
-Nick
 

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Hi spot blueing can be used to check for flatness, and is probably your best bet for something you can do at home. The surface finish, doesn't look bad from the pictures in my opinion. I worked in a machine shop that made parts for honda, water pumps, oilpans, rock shaft, cam shaft holder type of stuff.
Generally, if you can feel it catch on your fingernail, it's something that needs measured if it's high Some of what you see may be porosity, all cast stuff has porosity.
Take this all with, we didn't make heads, and I'm unfamiliar with tolerances on heads.
 

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Discussion Starter #3
Hi spot blueing can be used to check for flatness, and is probably your best bet for something you can do at home. The surface finish, doesn't look bad from the pictures in my opinion. I worked in a machine shop that made parts for honda, water pumps, oilpans, rock shaft, cam shaft holder type of stuff.
Generally, if you can feel it catch on your fingernail, it's something that needs measured if it's high Some of what you see may be porosity, all cast stuff has porosity.
Take this all with, we didn't make heads, and I'm unfamiliar with tolerances on heads.
The 10 or so lines on the right side of the cylinder in the first picture are easily distinguishable with a fingernail unfortunately.

Are you just talking about Dykem blue or something different?
 

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Dykem Hi Spot Blue. Doesn't dry, and will get everywhere if your not careful. I only say try hi-spot because without a granite block, using feeler gauges is difficult. You could do the * pattern if you had a true straight edge and catch a large issue.
With surface roughness, we had a special electric tool that would check, it had maybe a 2" stroke, so would measure areas of concern rather than a entire part. I cannot think of anyway to do this measurement at home.
If your concerned, your best bet is to call around at machine shops. Your not really needing them to have tooling to machine a head right now, just tools to measure flatness or surface roughness.
 

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I had this block reworked up the street by a small machine shop that is attached to an independence auto shop, both have great reviews. There were a fair number of aluminum I-4 heads sitting around when I went in so I figured my needs for a stock rebuild should be no issue. After picking the block up and reading about MLS headgasket surface roughness requirements I'm a little concerned...

There were a few bits of gall that had re-embedded in the aluminum that I got picked off with a razor but there are also some fairly deep hairline scratches in the aluminum that are distinguishable with fingernail. Out of curiosity I took a piece of 400grit wet/dry on a pane of glass and ran it over the deck a few times, careful to manage even pressure/strokes/direction. Certain areas between cylinders but still in the "shadow" of the liners smoothed out with other areas being untouched. Note that my thinnest feeler gauge sill wont pass under a straight edge. The liners are perfectly smooth, it's almost like a bit of the liner on the trailing edge of the cut broke off and gouged the aluminum as it was dragged by the cutter.

So am I being reasonable or neurotic? Again this build isn't intended to do anything but beat around on the street with barely over factory power numbers.

Thanks,
-Nick
Looks horrible. Should be almost glass like.(or at least fairly smooth) Many aluminum heads require an Ra of at least 30 for their headgaskets.. Some higher. Ra is roughness average and is measured with an Ra gauge. If the Ra is wrong,it will lead to poor HG sealing and eventual HG failure.

Id find another machine shop.
 

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Looks horrible. Should be almost glass like.(or at least fairly smooth) Many aluminum heads require an Ra of at least 30 for their headgaskets.. Some higher. Ra is roughness average and is measured with an Ra gauge. If the Ra is wrong,it will lead to poor HG sealing and eventual HG failure.

Id find another machine shop.
What Ra is glass like? What is a good milling operation?
"Glass like" is past any fly cutting, milling, surface grinding, and DEEP into a polishing as far as Ra is concerned. I've seen "2 micron" lapping tape used for rocker arms, but this wasn't ever referred as "glass like".
 

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Discussion Starter #7
Looks horrible. Should be almost glass like.(or at least fairly smooth) Many aluminum heads require an Ra of at least 30 for their headgaskets.. Some higher. Ra is roughness average and is measured with an Ra gauge. If the Ra is wrong,it will lead to poor HG sealing and eventual HG failure.

Id find another machine shop.
I assume you mean Ra less than 30?
 

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What Ra is glass like? What is a good milling operation?
"Glass like" is past any fly cutting, milling, surface grinding, and DEEP into a polishing as far as Ra is concerned. I've seen "2 micron" lapping tape used for rocker arms, but this wasn't ever referred as "glass like".
Perhaps glass like isnt the right wording. How about really,really smooth?
I assume you mean Ra less than 30?
No. "glass like" was a poor choice of words. With out knowing the spec for this head/block Ill say in general terms, acceptable aluminum finishes are in the 30-80 range. Your chosen shop should know what is correct.

All I can say is the pics you posted look unacceptable to me and my 25 years of experience in the repair industry.....
 

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Perhaps glass like isnt the right wording. How about really,really smooth?

No. "glass like" was a poor choice of words. With out knowing the spec for this head/block Ill say in general terms, acceptable aluminum finishes are in the 30-80 range. Your chosen shop should know what is correct.

All I can say is the pics you posted look unacceptable to me and my 25 years of experience in the repair industry.....
What repair industry were you in? I know to always question my 12 years of O.E.M. machining, and my quest for more info.
 

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Automotive.
That's very vague. There's a lady in my town that repairs automotive seats, and she's excellent in her automotive repair. She did seats from 1960s and earlier, and I'm just waiting to use her services.
 

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That's very vague. There's a lady in my town that repairs automotive seats, and she's excellent in her automotive repair. She did seats from 1960s and earlier, and I'm just waiting to use her services.
Im a 25 year Master Certified automotive repair technician. Ive literally replaced hundreds of HGs and have done at least several dozen engine rebuilds. (although now I mostly do electrical/drivabilty/diagnostic work)

The matter being discussed here is engine rebuilding 101, its not that complex at all and best practices for HG/cylinder head replacement are commonly known.
 

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Discussion Starter #16
So I finally got around to getting the block back to the machine shop. They were kind of embarrassed that it left the shop in the condition that it did. They re-decked it and it is nearly flawless. They don't have an Ra meter but it is about as smooth as I could see it being without having it done on a surface grinder.

Now I've had a chance to start gapping the rings and find that the ring gap is at or over the honda service limit with brand new rings... First one I checked was the cylinder that was bored for a .25mm oversize piston and it's .027" gap on first ring and .017" on the second ring. Lovely place to be since the whole point was to replace my bottom end with the Honda TSB for oil consumption.

Even if they were willing to redo or refund the cost of the boring I'd still have to buy a full set of new pistons which I did want to do... FML.
 

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So I finally got around to getting the block back to the machine shop. They were kind of embarrassed that it left the shop in the condition that it did. They re-decked it and it is nearly flawless. They don't have an Ra meter but it is about as smooth as I could see it being without having it done on a surface grinder.

Now I've had a chance to start gapping the rings and find that the ring gap is at or over the honda service limit with brand new rings... First one I checked was the cylinder that was bored for a .25mm oversize piston and it's .027" gap on first ring and .017" on the second ring. Lovely place to be since the whole point was to replace my bottom end with the Honda TSB for oil consumption.

Even if they were willing to redo or refund the cost of the boring I'd still have to buy a full set of new pistons which I did want to do... FML.
Bummer, at least you learned a little something about machine work and what should be acceptable.

The fact that the block looked the way it did initially kinda points to the quality of their work. Machinists tend to be perfectionists and that block screamed "I dont care".....
 

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Bummer, at least you learned a little something about machine work and what should be acceptable.

The fact that the block looked the way it did initially kinda points to the quality of their work. Machinists tend to be perfectionists and that block screamed "I dont care".....
They've got a younger guy that appears to be doing the bulk of the work, very enthusiastic but I don't think he's very experienced in engine machining, and I also don't think he's getting much guidance. Very nice guys to deal with but that won't be any consolation if my build fails.
 

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I'm sorry you had a bad experience with a machine shop.
I've discovered that unless you go to a shop that specializes in your particular motor (whether it's a Honda, Mitsubishi, Subaru, whatever), most machine shops only care about V8s. Sucks, but true.
 
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