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B/RB big block performance tricks

Discussion in 'Performance' started by TWX, May 21, 2008.

  1. dana44

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    Brock, you just figured out the truth. Polished surfaces are great when you start out on the line with a torque converter allowing a stall of 3000rpm and above. This is not what a person does on a daily basis, unless your friends are the local law enforcement and can get away with it. One reason so many people have a negative perception of ported and polished heads for street engines is because the fuel sticks to smooth surfaces and the air keeps going, after a time the engine carbons up and that's why you see so much excess revving to "clean out the carbon" because of the fuel that has baked and stuck to the surface start catching even more fuel and then it just gets worse, essentially washing the port surface from the excess coking fuel to make her run better.

    Now comes the fun part. I have seen guys use sandpaper rolls of 60 grit. This makes deep scratches and rings around the port surface, and the problem is, it is going the wrong direction, kind of like panning for fuel. If you culd get them to go the direction of the flow it would be a different story, but you can't. Discovered a long time ago, as you noted above from an earlier post of mine, carbide burr cutters leave little chips and thiny, almost invisible dimples in the surface. As it turns out, this keeps the fuel from sticking to the port surfaces at very low air flow speeds, so the fuel remains suspended.

    Couple months back I had to remove the intake manifold on my 02 PT Cruiser for a leaking thermostat housing. Somehow I managed to drop one of the bolt into the bottom half of the intake (it is a two piece unit), so I had to pull the bottom half off to get the bolt out, it was too deep for the grippers and fat fingers I have. Back in 2005, with 34,000miles, I ported the head on this engine, never took it apart except for a timing belt, but no change in anything with the head. I did this at 105,000miles and I got to look at what the ports looked like. When I ported the head the ports were black and mild crud inside the ports, maybe .020 thick and a little greasy from the PCV valve fumes that get sucked into the ports. All the heads look this way, I had purchased a head with 45,000miles on it, looked the same. When I looked into the head and it was just as shiny as when I ported the head except for the two outside sides of the port. In looking at the flow, the entrance to the port is narrower than the outside, which slightly flares outward to the ports, which is expected given the shape, nothing can be done about it without widening the port at the intake manifold, and the intake manifold. the thing was, the dirty part was about the size of a pecan half on either side, the rest was spotless. I have seen ported and polished heads that looked like stock heads after 2000 miles, mine had 71,000 miles on it and I could see 80-90 percent of the chips in the surface from my carbide burr cutter still.

    To your 906 head, as I said, don't use sandpaper rolls that are rougher, it will act the same way as a supposed professionally polished head, it has to be the burr cutter. The key is the little cupping thing the burr cutter does, it gives the surface tension to keep the fuel suspended in the air.
     
  2. Brock1980

    Brock1980 New Member

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    Wow that's alot of info thank u. Lots to think about. I don't really no the order of how to redo my heads cause I haven't done this before. But I am guessing. 1 I take the heads to the guys at Almax where I got my block done at. And get them to take it apart. 2 then get them to tell me what to die grind I a pretty sure I can figure it out. 3 then take them back to get all new parts.
     
  3. dana44

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    You can do a search on porting heads, the videos can show you where to take the metal out, how to do the short side turn, bowl work, gasket match the ports of the head, intake and exhaust, remove all the sharp edges. When it comes time to take the sandpaper rolls to the ports to supposedly smooth everything out, forget it, that's where the heads become worthless for the street. Magazines can do the same thing, they are constantly showing what to port and how. They will show flow numbers like a stock head flows 225cfm, then through the steps they get it up to 275-300cfm, and then they polish the ports and get between 3 and 5 cfm more cfm. These last couple cfm aren't going to be noticed anywhere on the street, Smooth flow keeping the fuel and air suspended is more important than 3-5cfm.

    You are going to need a very large capacity air compressor, a die grinder, and carbide burr cutter, I prefer one about the size of your index finger, rounded on the end. There are little electric ones, some are OK, others are junk.
     
  4. Brock1980

    Brock1980 New Member

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    Great thank u. I am hoping my order of the way to do it is right. I will search for videos for more help. And I have both electric and pneumatic grinders. So good there. Leave it rough ok. Port and polish but hold the polish. Lol
     
  5. dana44

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    The carbide burr cutters make it smooth in a way that flow remains moving at low rpm, which is the problem with polished smooth surfaces.
     
  6. triple j

    triple j Guest

    When I worked at the engine shop, we did a lot of gasket matching and porting and not much polishing. I've heard about this extrude hone process and it seems to work well. Also, if you go to zero deck height, with the compressed distance on the head gasket, you will have almost perfect quench distance. I'snt that cool!
     
  7. rockosocko

    rockosocko Member

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    Has anyone tried/still using Water/meth injection on the 440's? (or if anyone is CONSISTENTLY using it, and the results)

    Found a '75 Motor Home for screaming cheap and only showing 32K.
    440 and a BIG 727. Going to 'saw-zall' the sides off and pull what I need from what's left.

    thought it would be a good candidate for my '66 yorker.


    AND, if using water/meth. is there any pre-requisites for compression of such a usage?

    Thanks E
     
  8. hemi605

    hemi605 Member

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    for information only the new trick flow heads for big block mopars will be available july 2015.
     

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