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.

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

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.

Talyn said:

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.

Click to expand...

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

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.

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.

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

I left mine at 80 grit.

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?

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

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.

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

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?

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.

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

Your volumes are definitely within measuring error. I always used a set of telescoping gages to try and reproduce specific dimensions throughout the port.

I dropped the head off at the machine shop. Asked for it to be checked over and a 3 angle valve job with the valves back cut at 32*. They were impressed with the work I had done.

Good tip on the telescoping gauges. I uses some pieces of plexi cut to various sizes or circles to compare the sizes on various items.

I started on opening up the intake manifold a bit today (1999+ style). I'm not going to go all the way to the gasket though, just a bit inside it. I figure its better to have a smaller port on the manifold side than a larger port on the manifold side and a smaller port in the head.

The bosses for the fuel injectors are interesting. Cylinder's 3 & 4's project more than 2 & 5 and 1 & 6 are even less so. I figure this was done on purpose as the longer runner corresponds to a smaller boss. I don't think I am going to do much to them unless someone can say otherwise. I could take a good bit off and smooth them off, but I don't know if that would be a good idea or not.

Any suggestions on the intake manifold?

Talyn said:

I started on opening up the intake manifold a bit today (1999+ style). I'm not going to go all the way to the gasket though, just a bit inside it. I figure its better to have a smaller port on the manifold side than a larger port on the manifold side and a smaller port in the head.

Click to expand...

Its actually the other way around. Make the intake manifold the same size or .050 larger, any smaller and you will loose power. It has to do with the barier layer on the manifold wall.

~Alex

Alex how about a little bit deeper explination of that.........As i to would have beleived that the air stream hitting a wall,(head face of port, being larger then manifold))
would be lost performance........Not gain????


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