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Re: Throttle Body & Intake Manifold Polishing

In a message dated 8/30/99 5:09:30 PM Eastern Daylight Time, 
River6822@aol.com writes:

<< Although this issue has been covered in the archives, I still have a few 
 I have an 88 80q I5.  There is a leak in the intake manifold gasket, or that 
 it what I assume, so I have to take it apart anyway.
 1) What should I use to polish the throttle body and the intake manifold ?
 2) Is there a point where the throttle body and intake manifold can be too 
 smooth ?
 I can have the whole thing electropolished, but will it be too smooth ?
 A friend voiced a concern that with carborated motors, you could get things 
 too smooth and the fuel would not mix correctly.
 3) Has anyone done this before, or even high grade polishing ?

    I have ported a few intake manifolds.  It is quite easy on the later two 
piece, I have used a sanding stick and sanding rolls to do most of the work, 
and finished with a medium cross buff (from Standard Abrasives).  A sanding 
stick is a 1/4" rod with a 7/8"cut in the top to hold an 8" piece of 
sandpaper strip that is rolled around it.  First hit it with some 80 grit 
sand paper rolls (WD40 help here) till all the roughness is out of the 
casting (port matching should also be priority).  I'm not sure how importand 
turbulence is in the IM, but it is important to have a reletively rough 
surface in the intake ports in the head (say a 120 grit finish).  I also work 
the insid of the chamber where the TB bolts up, removing a little material 
here and there and smoothing things up.
    I would not spend too much time on the TB, a little polishing there is 
going to be very negligable.  Dont forget that that basic TB is also used on 
the 20valve's which are flowing quite a bit more air than your 10v.  We are 
not talking huge power with any of this stuff, put is will help in extenting 
your rev range slightly as it did in my coupe GT (see web.csuchico.edu/~javad)
Javad Shadzi
88 80Q