Hello, has anyone ever polished the intake and exhaust ports in the cylinder heads? I suppose it would be best before having the head rebuilt.

I have heard that on gas engines the porosity of the surface of the intake port helps to keep the fuel atomized. I was thinking on our diesels there is only air that flows through the intake and exhaust ports so it would'nt hurt to polish up the surface of these ports....but am not sure.

I am not interested in removing material from the head....rather just clean up any suface imperfections and give it a bit of a shine.

How well does polishing work on cast iron?
Thanks.

Back in HS when I was into American V8s we used to port match the intake and exhaust. we'd take the gaskets and place it on the head and then grind away the extra metal so every port matched the gasket, and then did the same on the manifold. The idea was to provide a smooth transition from head to manifold.

As I grew up and learned more about engines... and had my time eaten up by "adult responsibilities" I haven't gone back to polishing or porting anything. Your going to invest a lot of time and get neglagable power gains. Its an excellend project when you have more time then money... like when I was in high school lol Its not that its a bad idea, its just a bad time investment.

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Forum member Doktor Bert has done this to his 617, among other modifications. In the 1st thread he posted to this forum way back in 2005 he describes some of his work.

New member First Posting:

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Joe

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1980 300SD - 495k miles - 'The Ambassador'
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I ported my manifolds, head, turbo adapter, and turbo (exhaust inlet side). I didn't polish any surfaces because I'll be spraying methanol in the intake, and the exhaust's coating of soot will smooth things out.

My OM617 Build

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$60 OM617 Blank Exhaust Flanges
$110 OM606 Blank Exhaust Flanges
No merc at the moment

Wow - nice thread - I think I should venture to other sites more often...

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
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I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

The stock exhaust manifold can make significant improvements, there was a grape-sized irregularity in one of the runners.

Unfortunately I don't have any photos of the turbo, but my GT2056V's exhaust inlet was a good 1/4" smaller than the gasket.

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$60 OM617 Blank Exhaust Flanges
$110 OM606 Blank Exhaust Flanges
No merc at the moment

Thanks for the link, I have started already with a small sanding wheel that kind of looks like a cylindrical flap disc. It is probably going to take a sanding wheel with more courser grit cause this one is 80 grit and it is taking forever to get the sand cast finish down to a smoother finish that could be polished.

I got some felt wheels and some black clay polishing compound. I have never used this stuff before. Am I suppossed to melt this clay bar and dip the felt wheel in it or something? This clay bar is made by Enkay. I have scraped some of the clay into powder but it just blows away. I am starting to think that this is ALOT of work and perhaps why you guys are saying it is alot of work for nothing.....

I'll clean it up as best as I can but can't see myself having the patients for a magazine quality polish job like I had envisioned before I started.

I can see this grape sized imperfection in the #2 exhaust manifold runner. It is hard to say because that is the cylinder that had the broken guide...but there is alot of carbon build up in that ex. runner compared to the others that appear to be fairly clean.

I think my time would be better spent removing that excess on the exhaust manifold.....so can I remove that grape sized addition without worry....meaning I am not going to find out it was cast that way for a reason? Did you guys remove it and make it entirely smooth?
Thanks

usually polishing compound is put on the wheel while it is spinning by just letting it rub on the wheel.

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1977 240D turbo

You might want to consider extrude honing. I don't believe that its meant to polish manifold runners to come out to exact gasket matching, but if you have already ground down the ports to match the gasket at the entry point then the extrude hone will do an amazing job on the internal passages. Almost truly a buffed mirror like finish.

I've never had it done, but used to have some conversations with an old hot rodder named Smokey Yunik. He swore by it, and of course it does the entire internal passage of the manifold runners, so the flow is smooth for the entire trip.

Seems like these projects are best performed on a spare manifold that you can work on at a leisurly pace.

Even the port enjection EFI pro guys dont go finer than 80 grit in manifolds or intake ports - and dont polish.

I am not sure if my exhaust manifold has the grape sized imperfection....I looked at it again and the surface is obscured by the intense amount of carbon build up on the number 2 port when comparing it with the others. It is actually chocking that cylinder off. I did'nt notice until looking at it more carefully what was in there....probably a quarter to three eights of an inch all the way around the port. I thought this ran good and can't wait to see it run with that cylinder working properly.

What is good to soak these parts in....intake and exhaust maniold...pre-chambers. I have them in varsol. Thanks

I would post more pictures but the camera is now broken

If you still want to polish:
You need to run your polishing tool on the bar of rouge until it melts into the wheel, then polish the metal, and repeat.

To remove carbon any basic cleaner will work: biodiesel, simple green, greased lightning. Just be careful with any of those on aluminum-prolonged contact will cause it to corrode.

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$60 OM617 Blank Exhaust Flanges
$110 OM606 Blank Exhaust Flanges
No merc at the moment

Thanks, I don't think we have any shops that do extrude honing around here (I wish we did). I used a different exhaust manifold altogether and used several different chemicals to get the crap out of the intake. I think there is still a wee bit left in there but I gave up. I am tired of cleaning parts and it is not very good for my health. The prechambers came out looking like brand new. I did use the advice on how to apply the polishing compound. I had visions of polishing everything aluminum on the car after doing the ports. The ports looked pretty and shiny when finished, but that is way too much work. I put all that polishing stuff in a coffee can and I guess that is were it will stay for the rest of its life. The valve cover will be keeping its dull finish as well as everything else I had hoped to polish...I now know why I don't see more of these with all their aluminum polished up....it's just way too time consuming, just like you said Sir Nik 84.

see post #10