OMG- What a pain! Used the air die grinder- emphasize die. Also used a dremel for some hard to get areas. Had to delay working on them until my kids bronco was painted and outside.

After a few hours of stone grinding hell I had a friend give me a xmas tree shaped carbide cutter for my air grinder. What a differrence that thing made- gotta be careful cause it removes some metal quick but it makes MUCH shorter work of the porting AND it leaves a nice semi smoothe surface that is still just a tad bumpy to get the air flowing better- at least thats my theory.

I was amazed at how much metal came out of the ports when I collected the dust with a magnet. I put air to the valve and could tell how the air flows and worked on it accordingly. Would love to get them flow tested.

polishing the combustion chamers was a whole different animal but I found a tool for the dremmel thats like an abrasive scotch pad that polishes nicely once the bumps are removed- they do remove some metal too and one will last for both heads if you don't cut them off by mixing it up with he spark-plug hole. Saved a lot of work. So they are off to the machine shop tomorrow for intake and exhaust seats (stainless) and 2.19, 1.71 valves- shrouding will be an issue of course with the 2v heads.

getting closer!

 

That kept you busy for a few hours. Please post the part number of that dremel polishing pad.

 

i threw away the packaging- will buy some more and get the # to you then.

 

No need to go out and buy anything special. I am glad I am not the only one that throws away the packaging without noting the number for next time.

When doing head work an old spark plug without the side electrode is useful as are old valves.

 

I've read some places and seen some sites which sell stones and discs only. I would never attempt to port iron heads without a carbide burr. Even at that I'll bet I had at least 5 hours in each head. Hope the fruit of your labor pays off big!

 

can you post some pics of your porting and polishing job??? i would be intersted in doing this but i know nothing about doing anything like this. how hard of a job is it? and how nice and even does it have to be?
thanks
Mitch

 

The exhaust port should be smooth, but the intake port should have some roughness. Roughness creates turbulence and prevents wetting of the wall by the fuel. Of course with Fuel Injection, there is no fuel to wet the wall, so the intake ports should be polished in that case. The valve pocket should be cleaned of all edges, and the bowl blended into the port.
I am not sure that the combustion chamber should be polished. There should be turbulance in the combustion chamber for the best burn.

 

The polishing of the combustion chamber is supposed to get rid of possible hot spots that can cause detonation- supposed to be important if your running hotter fuel etc. polishing still leaves plenty of uneven surface area to help with mixing the air/fuel. Not much to polish in the closed chamber heads.

I didn't do much at all to intake runner- I spent time blending the bowl under the valve to try and help the air flow better to the edges of the valve- I don't know how to describe it but most of the air seemed to flow on one half of the runner and thus one half of the valve- I don't think you can successfully get the air to flow anywhere near equal in the port and bowl areas so I figured it was best to get rid of the edges etc that disrupt the flow in the high flow areas. It has been said that over porting in the wrong areas hurt the flow dynamics so I was pretty careful and did not go anywhere near overboard so I would imagion there is room to play in my heads. I already have too much $$ in these aussie heads to screw them up.

The exhaust ports are another story and I was far more aggressive there. Again the flow is in half the port- so getting that pathway a bit bigger and smoothed out was a major goal- the carbide cutter left the surface just how I wanted it. Then taking a little off the bump where the water passage is and where the head bolts come down was secondary without aggressive tooling.

hope this helps- the first head was a lot more work than the second as i got a routine down but I still spent 4 hours on the second head and my air compressors are still whining. the carbide cutter is like new- amazing! I still used some stones as they work better in some areas- I have a couple that I like cause they were the right shape for one area when i started then they fit into the other areas as they ground down. It felt good to drop them off today but I didn't take pics- i'll do it when i get them back- before i put em together which will be another 1st.

 

Turbulence in the combustion chamber does not come from surface finish. It comes from airflow direction and velocity in the port. The polished combustion chamber surface reduces deposit formation and hot spots that can cause predetonation.