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Jeep Street and Performance Do you like to go fast in your Jeep?

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  #1  
Old May 11th, 2008, 17:52
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Talyn Talyn is offline
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Polish and port, take 2

Started on the good head this weekend. I opened up the intake and exhaust ports a bit. Not entirely the size of the gasket. Then blended the ports back and clean up the casting. I cleaned up the guides to make the smoother. Same thing with the remaining guide in the bowl (remove them completely if possible). I didn't do a lot of work on the bowl other than feathering any sharp edges between the machining for the seat and the bowl. The Short side radius was the same.. not a whole lot of work. I think I have most of the mass work done.

I'm going to attach some images, but most are in a quick gallery I set up here: http://jeep.blackonyx.net/forum/pnp2/

I don't know if I should do any more work on the guides or the bowls. I know I still have to clean up the exhaust side some more and I haven't even started on the combustion chambers yet.

Where the bowls meet the valve seat machining there is some casting sticking out on the sides... Should I grind that down a bit?

You can see it in these two pics pretty well, on the left:


and on the right:



Some more pics, rest in the gallery mentioned above.










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  #2  
Old May 11th, 2008, 20:34
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Re: Polish and port, take 2

Its always hard to judge a port from pictures, its just nowhere as detailed as geting your hands on the head and feeling the contours of the ports. It does look good in the pictures. Just get around the guide with the sandpaper roles to reduce the casting bumps to keep the fuel/carbon from sticking there.
When it comes to the intake manifold, make sure the intake opening is the same size as the head to .050 larger. If the gasket side of the intake manifold is any smaller than the port in the head it will hurt the power, a little large has no negative effect on power.
If the head has already had its valve job then it would be a good idea to place an old intake and an old exhaust valve in when doing chamber work. If the stone or sandpaper slipps it will not be able to hit the seat and cause any damage.

~Alex
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  #3  
Old May 11th, 2008, 20:49
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Re: Polish and port, take 2

I have someone sending me some not so good valves to use for that purpose. The valve job has not been done yet though, but I also don't want to gouge the seats. What do you recommend that I do with the area where the seat machining meets the throat? its not like that on all of them, just a few, and IIRC its mainly on the intakes.

As for pics, It is pretty hard to take pics and show depth.
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  #4  
Old May 12th, 2008, 18:25
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Re: Polish and port, take 2

Quote:
Originally Posted by Talyn
I have someone sending me some not so good valves to use for that purpose. The valve job has not been done yet though, but I also don't want to gouge the seats. What do you recommend that I do with the area where the seat machining meets the throat? its not like that on all of them, just a few, and IIRC its mainly on the intakes.

As for pics, It is pretty hard to take pics and show depth.
Just blend the sharp edge from the carbide cuter (the 60*) into throat of the port. Do not blend the angles up to the seating angle (narrowing angles) of the intake port, it will actually hurt the flow. Before the days of the flowbench, head porters would blend all of the narrowing angles to form a radius. Ex: the intersection of the 60* and the 45*. The air can stay atached to the port wall if the angle is 15* or less, for most ports.

~Alex
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Old May 17th, 2008, 19:50
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Re: Polish and port, take 2

Made some more progress today. I got rid of the remaining casting form the valve guides on the exhausts and feathered the intakes some more. I'm down to the 80 grit rolls on the exhaust side. What grit should I stop at on the intakes? Some people have told me 40 grit, others 80. I've been pretty careful not to touch the valve seats, but I did hit them a few times.. not too deep, but I will be getting a valve job anyhow. As for the casting that went up to the machining under the valve seat I flattened that out a bit. I figured that it was only on 3 of the intakes and the others weren't that way.. just made them all match.
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Old May 18th, 2008, 08:10
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Re: Polish and port, take 2

Ok.. went back and re read the previous thread (I knew someone said it, just couldn't remember where)and you guys say 80 grit on the intakes. I thought it was pretty smooth, but I guess at a molecular level that is pretty rough.

I should have some more pics tonight.
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  #7  
Old May 18th, 2008, 13:33
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Re: Polish and port, take 2

I would stop at the 80 grit for the intake, the little bit of roughness will keep a boundary layer of turbulant (sp) air that will help to keep the fuel from sticking to the walls.

~Alex
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  #8  
Old May 18th, 2008, 14:31
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Re: Polish and port, take 2

I left mine at 80 grit.
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  #9  
Old May 18th, 2008, 20:08
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Re: Polish and port, take 2

After about 32 hours I have the intake and exhaust are done. The exhaust was polished and the intake was stopped at 80 grit. I think the results are pretty good. The cross buffs that came with the kit are pretty useless as they are too larger for the Jeep's exhaust ports. I ordered some 3/4" ones and they are a perfect size.

I still need to do the 5 remaining combustion chambers. I decided I won't be de-shrouding the exhaust valve as after tracing the gasket onto the head I really don't have that much room for de-shrouding before I hit the gasket. You can some what see the scribed line in the first image below.

Any tips for getting into the light space in the combustion chamber? The rolls seem to what to disintegrate when they hit the base casting.

Anyhow, let me know what you think. Some pics below and the rest are here: http://jeep.blackonyx.net/forum/pnp3/










Oh yeah... about my combustion chamber measuring episode... paint thinker and acrylic don't mix well.. one dead buret and no measurement.. long story short: started with some tranny fluid and alcohol.. they didn't mix very well... so I used some tranny fluid and paint thinner... but didn't think ahead to realize that the paint thinner was going to melt the acyrilic buret. In goes the fluid... some drips down the side.. interesting... the graduations are moving down.. and its fogging.. oops. Oh well

Two questions on that.. 1) what size should the hole in the plexi be and 2) what do you use for the fluid?
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  #10  
Old May 18th, 2008, 20:55
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Re: Polish and port, take 2

water will work just fine as long as you dry the head and wd-40 it when you are done. the hole in the plexi should be a little larger than the burret and drilling a vent hole above or next to the hole will help you out alot too.

~Alex
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  #11  
Old May 18th, 2008, 20:59
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Re: Polish and port, take 2

I thought about the vent hole.. but I thought it may throw the results off. I'll give that a try if I run in to problems.
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  #12  
Old May 20th, 2008, 19:01
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Re: Polish and port, take 2

More progress. I have 5 of the 6 combustion chambers done in 80 grit. One polished up (seen above) I saved the last one for when I cc for a base line. One thing that has been bothering me... do other head gaskets have different "bores"? I have the Mopar performance one and I don't see how anyone could unshroud an exhaust valve... there is just not enough room.

-Chris
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  #13  
Old May 22nd, 2008, 18:15
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Re: Polish and port, take 2

I CC'd the head tonight. I started with the chamber that I hadn't touched yet that is #1

1: 57.2
2: 58.4
3: 58.6
4: 58.2
5: 58.0
6: 58.4

Should I do anything to bring them all alike, or is the variance not enough to worry about?

Also, I have been thinking about my manifold gasket. I used the one that Doug Thorley sent me. When I port matched the intakes I didn't need to remove that much material. Now I am debating getting another gasket and port match to that if it is larger. Would that give me any gains or not?
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  #14  
Old May 22nd, 2008, 20:18
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Re: Polish and port, take 2

I forgot to add a bit of humor..

After reinstalling all the springs I got #1 cylinder ready to cc. Put the plexi with vaseline on the head and started adding water... it started pouring out the chamber.. i them remembered that I need to install the spark plugs.
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  #15  
Old May 22nd, 2008, 23:44
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Re: Polish and port, take 2

I've done that a few times, either forget it all together or put it in the chamber next to the one with the plexi and valves. Those are good consistent numbers for a hand polished chamber.

~Alex
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