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Head Questions

Discussion in '40- & 55-Series Tech' started by offcamber40, Sep 26, 2003.

  1. offcamber40

    offcamber40

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    OK,

    I just picked up a used head that I am going to have rebuilt for my fj40. I believe it is off a 77. My vehicle is a 76. On the believed 77 head there are six sort of injection ports right where the intake manifold hits the head. On my 76 I have screw in blockoffs (with square heads for removal) at these locations.. my question is what are these little ports (something screws onto them because they are threaded at the end)? Each one goes through the head into the intake ports right near the valves. They are obviously removable with a socket or box end wrench, but will my 76 blockoffs screw into the same holes? I have no idea what I am looking at, so any help would be appreciated..

    Mike
     
  2. cruiserman

    cruiserman

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    Sounds like fittings for the air rail. Scroll down.
     
  3. Rice

    Rice SILVER Star

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    Double check to be sure they don't screw into the exhaust port. As Cruiserman said it sounds like the air injector nozzles go there. The function is a part of emissions ... air is pumped into the exhaust (and it's done at the head because there is still lots of heat energy left over) in order to help use up left over hydrocarbons. If someone removed smog stuff at a earlier time they would have simply plugged the holes and removed the air pump from the engine.
     
  4. offcamber40

    offcamber40

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    Cool, thanks guys.. That is exactly what I am looking at. After going over the head today, it looks to be in pretty good shape other tghan the fact that the PO obviously never changed the oil. Im going to have it magnafluxed, hot tanked and decked, then put it back together with new seals. Another question.. Looking down into the water jacket fromn the no 1 cylinder, it looks like there is a ton of casting waste/sluff off at the center seam. Is this normal? It looks like a bad casting job to me. Im afraid little bits will slowly come loose and block the radiator? Thanks for the help!
     
  5. cruzer

    cruzer

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    I don't think the casting flaws will cause you much concern. Two suggestions

    1) make sure you get GOOD valve seals...not the crappy FelPro umbrella kind they suck and will leak. Makre sure they have the wire retainer rings on them...just go to and engine rebuild place with a valve and the head(probably the place you are getting it decked will have this stuff on hand for you).

    2) When putting the new head gasket on as you look at the head you will see on the passenger side a seires of bananna shaped holes..these are water passages in your head. Now if you look at your head gasket you will see some of them are blocked off(i think the front 2 or 3) and the rest have very small(less than 1/4in) holes) but that the head has like 3/8th(or bigger) holes. This was done by Toyota to increase the head temperature so that it would burn off the unburnt gasses better. If you have access to a Whitney Punch (hand punch for Sheet metal) that is big enough i suggest you open the holes in the head gasket up to the size that the ones in the head are. This will help with cooling your engine better because you will have more flow. I did this on my engine and it dropped the temperature down about 5-10 degrees after my rebuild. (next time i rebuild a 2F i am going to do all the holes but don't suggest this cause i don't know for sure what will happen :p)

    Oh and i used Felpro head gasket and intake/exhaust manifold gaskets and they worked great.

    HTH

    Stew
     
  6. offcamber40

    offcamber40

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    Ok, a couple more questions.. when I get the head decked, does it requiree shimming? If so, how do I determine how much? Also, the number 4 intake valve was slightly bent, it pulled through the valve guide with some tension.. can I just replace one valve and retain the seat that is in there and match them by pasting the valve and seat? Ok now a couple more questions.. Im putting in a new RV grind cam, probably Downey or MAF. Downey says use reground stock lifters with high comprssion rate springs, MAF says buy new lifter with no new springs required.. what is correct? Also anyone with good experience with a particular cam? And one last question.. where if anywhere, can I get rocker arm replacement bushings.. mine have some play. Thanks everyone.