Intake Manifold

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When a so simple device wants to get all the attention...

I never thought that I would have a web page dedicated to an intake manifold, but here it is...

While I have an EA-81 engine, the EA-82 manifold allows for a simpler radiator hose installation.  The outlet is exactly where I need it.  Some people also believe that the EA-82 manifold enables a higher flow of gas/air mixture through its larger diameter passage.  But this is a debatable point.  The manifold needs a few modifications to allow the installation of a Holley 5200 carburetor onto it.  

It was supposed to be a fun and exciting day.  My goal was simple... start the engine!  That day, I connected the starter cable to the starter, put oil and coolant in the engine and then...

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I found that the intake manifold was leaking!  :(   It was not fun at all.  I removed the intake manifold and brought it to a local "pro" in making aircraft parts and welding.  He spent the better part of a day helping me to correct the situation.  Under pressure (1 to 10 lbs), it was leaking from all around the adapter plate both inside and outside.  This is most probably due to a pinhole in the weld that was sealing the water passage in the back of the original carburetor mounting plate.

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At the end of that day while the plate was now sealed all around, the water passage was still loosing pressure during our tests. I tested it underwater to see the origin of the problem and found it was now inside the manifold where it is impossible to reach with a TIG welding equipment.  I had a choice between cutting the manifold to remanufacture a part of it or starting over with a fresh intake manifold.

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This is the "fresh" intake manifold being converted.  It comes from a Subaru Loyale year 198?  that had a SPFI EA-82 engine (did'nt take time to check the particular car for year).

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Everything needs to be removed.  I kept the throttle body for possible future use.  I then cleaned the manifold, put a plate to block off the EGR thing, tapped some of the holes so I can put standard off-the-shelf plugs and more importantly, I enlarged the intake hole to match the pattern of my adapter plate still to be made.

I then made an adapter plate from a 1.5" X 5" by 4" block of 6061-T6 aluminum purchased at Metal Supermarket.  One of my friends has a small lathe/milling machine that he made available to me.  It took me 1.5 days to do this on his machine with a including several hours of setup or preparation time.  Oh... it took some more hours to cut the block in two parts using a vertical band saw before starting the milling job.  Thanks SO MUCH Gilbert!

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I tapped one hole on the side opposite to the thermostat to 1/8" NPT and I inserted a plug.  I also tapped the PCV valve hole to 1/4" NPT and installed a plug.  I cut the heater steel tube in front of the manifold to a shorter length and had a bracket welded by my friend at a more convenient location.  I also asked him to solder a wire around the end of the tube to have something looking like a bubble flare.  I also plugged a vacuum hole with a rubber cap.  Finally, I enlarged the bolt holes to accommodate the new size of my engine (heads are shaved .045").

 

 

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