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Started to do some porting.
https://slantsix.org/forum/viewtopic.php?t=32902		 Page 2 of 3
Author:  stonethk [ Mon Dec 22, 2008 8:43 pm ]
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I went easier around the exhaust stem-I dont think high temps. & thin metal work well together.
Keep em comin runvs-I wish more people would post pics of their port work :D
Its a good thing to exchange notes.
Author:  stonethk [ Mon Dec 22, 2008 10:48 pm ]
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The gasket is from GPRS not Aussiespeed.
Author:  terrylittlejohn [ Tue Dec 23, 2008 6:01 am ]
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nice job and photo`s, also who are gprs gaskets? and what was the price?
Author:  stonethk [ Tue Dec 23, 2008 6:13 am ]
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Here a link to the gasket, fast shipping and well packed too-
http://www.gprsmopars.com/shopping/pgm- ... ?id=5&=SID
Author:  Rug_Trucker [ Tue Dec 23, 2008 9:18 am ]
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I didn't have a camera when my head was done. When it comes off I will clean and do some pics.

What year head are you doing?
Author:  wvenable [ Wed Dec 24, 2008 4:58 am ]
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Stone, that gasket looks just like the one I got from Aussie Speed. I wonder if they are one and the same. Great job on that cylinder head! I will pick your brain after the holidays. Thanks, Wayne.
Author:  Reed [ Wed Dec 24, 2008 8:19 am ]
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I hear dthat intake ports should be polished but exhaust ports should have a rough finish. True?
Author:  stonethk [ Wed Dec 24, 2008 8:39 am ]
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The head is a '68.

Reed, from what i understand it is the other way around.
The intake should have some texture to keep the mixture-someone here used the term "charged" by having some turbulence.

I think :idea: that a smooth intake would be akin to dew on your windshield, any idle mixture would have an easier time sticking or puddling to a smooth surface rather than a semi rough one. But I dunno.

the exhaust you want smooth just to help the spent gases flow out as quick as possible with no turbulence.

I am sure there are some technicalities but this is what I have found so far
Author:  slantvaliant [ Wed Dec 24, 2008 8:43 am ]
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It's generally good to have some texture to a wet intake tract - one with fuel in the mix. If you were running EFI with injectors right at the valves, it would be less important. Hard to do in a slant head, so ...
Exhaust ports should be smoother.
Correct shape and a lack of obstacles to flow are more important than the exact surface finish.
Author:  runvs_826 [ Wed Dec 24, 2008 11:06 am ]
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Quote:
I hear dthat intake ports should be polished but exhaust ports should have a rough finish. True?
Like everyone has metioned, right idea, but backwards. The intake should be a little rough so their is turbulence, and for fuel injection assuming you just have air no fuel, the air like water to a boat will form a cushion and slide on itself easier than running against the cast metal. So, what's the finished product like? Happy with it? Looking at your pictures I'm going to have to go back and open them up another .2 in or so. Good to know I can because I know some guys were getting about 220cfm out of their slant heads which is darn good for a stock head. Idea would be about a cfm per a cubic inch, so with my 170 flowing a head with eh.... 190cfm and a blower :twisted:
Author:  slantfin [ Wed Dec 24, 2008 11:36 am ]
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It is my understanding that there should be a step up from the exhaust port to the exhaust manifold, with the manifold having the slightly larger cross-section, to create a slight obstacle to keep the emerging gasses from flowing back into the port.
Author:  Reed [ Wed Dec 24, 2008 12:17 pm ]
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OK, thanks! I knew it was one or the other. I have also been told that the intake port should be filed with a 40 grit stone. Does that sound about right?
Author:  runvs_826 [ Wed Dec 24, 2008 11:28 pm ]
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Quote:
It is my understanding that there should be a step up from the exhaust port to the exhaust manifold, with the manifold having the slightly larger cross-section, to create a slight obstacle to keep the emerging gasses from flowing back into the port.
I've never heard of this. I don't understand why your exhaust would flow backwards. I know that the intake can work like this hence the plenum, but I didn't think the exhaust worked like that. I thought it was more like the the correct length would fill the pipe the best at a given rpm blah blah. But the overall point is that porting would help open up the most amount of flow from the carb to the exahust tip. So your headers, intake, piping should all be a continually smooth flow.
Author:  68barracuda [ Thu Dec 25, 2008 3:02 am ]
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Quote:
It is my understanding that there should be a step up from the exhaust port to the exhaust manifold, with the manifold having the slightly larger cross-section, to create a slight obstacle to keep the emerging gasses from flowing back into the port.
Correct - help the anti reversion action - ie - it helps prevent the pressure waves forcing exhaust gases back into the cylinder while the valve is still open - to a degree
Author:  DusterIdiot [ Thu Dec 25, 2008 8:44 am ]
Post subject:  And...
Quote:
I hear dthat intake ports should be polished but exhaust ports should have a rough finish. True?
This is reversed, the intake port should be worked over but left a bit rough or turbulence, this also assists in keeping some fuel in the air stream during cold weather running until warm up can occur. Polishing the exhaust port decreases the surface area that any left over carbon from combustion can stick to and decrease the port cross section.

When gasket matching make sure you double check your intake against the gasket also, any port mismatches will have to be lined up/corrected, if there is a 'shelf' that will need to be blended as this creates some problems in the airflow: smaller ports can keep velocity 'up' but restricts the amount of possible flow in the runner, going from a smaller runner to a bigger runner will slow the velocity of the exiting mix/gasses a bit.

Everything looks pretty good.

-D.idiot
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