1G Pitting in combustion chamber

[AWD-Tony]

Pitting is pretty bad and I don’t want to take too much off. Should I bother polishing this?

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[Kryndon]

From what I've seen that's more or less normal after lots of miles on these engines. Yours isn't so bad, mine was a bit worse with the exact same style of pitting. When it's really deep, if you try to smooth it out and blend it you'll end up increasing combustion chamber volume which will throw other things off by a fair bit. In your case I think it's safe enough to blend it out a bit more, and then do some hand polishing with wet sandpaper. Personally I used those small bits for a dremel, the ones that look like little sand papers sticking out like flaps. Don't know the proper name. Grit 120/160 or so. But frankly you can just run it like this in my opinion.

 

[AWD-Tony]

Thanks for the input kryndon! This is my first time so I think I’m gonna stop there and not get in over my head. Just gonna rid the rough casting and smooth where machining ends.

 

[Kryndon]

You're on the right track. That's also exactly what I did recently for my first try. Take it easy for now and keep going more and more in-depth as you get to know these cars.

 

[1990TSIAWDTALON]

Flatten out any high spots, and as said, dont take out too much. You won't get perfect, but you and the motor will feel alot better!
High spots get hot and promote pre-ignition which is KNOCK so take those out and take your time.

 

[AWD-Tony]

That’s the plan guys and I realize it’s a ton of work to get it completely smooth. There are some spot where it’s extremely hard to get to with the limited tools I have. I’m staying away from the floor on the intake side and I noticed this. Should I leave this?

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[AWD-Tony]

Here’s a better pic

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[motomattx]

You can easily do more damage than good messing in that area, I would leave it if I were you.

 

[Alex_ jamaicanEvo9]

I have a 2G Head with similar pitting issue . So base on these recommendation im gonna flatten and polish as best as possible , But wont i interfere with the compression ratio in the cylinder?

 

[ThunderChild]

As long as you don't take an appreciable amount of material out then you won't noticably alter or affect the compression ratio. Just smooth the rough stuff and any high spots with a light sanding or scotch-brite ball and that should be sufficient. If you start going for a perfect finish, you'll have to recontour every CC the same which is near impossible to do for the average diy mechanic and basic tools.

As for the port floor casting flash, it shouldn't affect anything majorly, but you could smooth it out with a light sanding drum in about 30 seconds. But I highly doubt you'd notice a gain, it would only satisfy piece of mind.

On another note, I've noticed alot of my head castings have this pitting and rough finish tooling to the CC surface. Alot of my heads are Hyundai or N/T heads, but the one true mitsu 1g turbo head I have looks vastly superior in quality.

First two are Hyundai 1.8 and 2.0 heads, third is mitsu 1g turbo head. You'll have to zoom to see the finish in the CC, look to the left chamber, but I think the difference is pretty noticable even from a distance.

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notice purity and cleanliness of the casting finish on this head VV

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[AWD-Tony]

I have a 2G Head with similar pitting issue . So base on these recommendation im gonna flatten and polish as best as possible , But wont i interfere with the compression ratio in the cylinder?

If it looks like mine, you’ll have to remove a decent amount to get it completely smooth. I used a 320 grit scotch brite on a dremel for 1 minute durations per chamber.

 

[motomattx]

Hyundai and other brands used what seems like a much less pure aluminum maybe its recycled aluminum, and the castings seem like they were old Mitsubishi molds that were past their useful life, that or they took a Mitsubishi head and just made a cheap mold off of it and used that rather than using Mitsubishi blueprints to create a high quality mold.