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Registered
Join Date: Sep 2003
Location: Granbury, Texas
Posts: 47
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Boring out MFI throttle body
I purchased a complete MFI system from a Pelicanite and the throttle bodies are not as pristine as I would like. There is some pitting of the bores that I have tried to smooth out the a brake M/C hone. It has smoothed some but not completely. I know this sets me up to need larger throttle plates but that is what I have. I don't want to send them off the Eurometrix because I cannot justify the $1000 to do it. Does anyone have experience with this? It looks to me that the bore is a "simple" taper unlike the throttle stacks that taper from both ends to the middle. I know there is one DIYer who has tackled this. Oh and by the way I don't have a machine shop in my garage!
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03-11-2004, 05:16 PM
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Join Date: Jan 2002
Location: Long Beach CA, the sewer by the sea.
Posts: 37,720
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Where are you going to get the bigger plates to fit your boring job? (That didn't sound right, but you know what I mean
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03-11-2004, 05:28 PM
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The plates are actually all the same size between T,E,S and RS.. 38mm if I recall correctly. The difference is the narrowing after the throttle plate. I'm having a set bored out to 32mm from 31mm (to match the ports on my heads) by my machine shop. I didn't see the justification in the $1000 either since my throttle shaft bores were just fine.
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Tim 1973 911T 2005 VW GTI "Dave, hit the brakes, but don't look like your htting the brakes...what? I DON'T KNOW, BRAKE CASUAL!!!" dtw's thoughts after nearly rear ending a SHP officer |
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03-11-2004, 05:31 PM
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Join Date: Jul 2001
Location: Springfield, MO
Posts: 1,422
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Talk to your local platers. They might have some ideas about what you could do to fill in the pits.
Good luck with your project. David Duffield |
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03-11-2004, 05:37 PM
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hmm.. just a thought.. if it's not in a critical area(throttle bushing or seating area but just for general smoothness what about JB weld? Just a random thought
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Tim 1973 911T 2005 VW GTI "Dave, hit the brakes, but don't look like your htting the brakes...what? I DON'T KNOW, BRAKE CASUAL!!!" dtw's thoughts after nearly rear ending a SHP officer |
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03-11-2004, 05:39 PM
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Join Date: Sep 2003
Location: Granbury, Texas
Posts: 47
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Interesting thoughts guys. If it ends up I need larger butterflies I will convince one of the machinists I work with to make me some. They aren't that sophisticated a part. Has anyone taken these apart? Look at how large the butterfly shaft is. I remember 20 years ago on carbs everyone wanted to make this part thin to remove an impediment to air flow. Has anyone else tried to machine down the throttle shaft?
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03-11-2004, 05:44 PM
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Join Date: Jan 2002
Location: West Lafayette Indiana
Posts: 1,421
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Find a common holley carb butterfly plate that is slightly larger than the stock 38mm, purchase six of them, and then bore you throttles to that dimension. You can get some sets that don't yet have mounting holes in them so you can have the new butterflys mounting holes made to match your thottle plate shafts.
 You realize the bottom of the throttle body is taperd to a small diameter hole for the T, E, or S engine. If you open the bore up all the way down, you will have a shoulder where the body meets the head port and that ain't to good. Whether or not to open up you ports and the corresponding bottom throttle bore is for another thread though.
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Dennis H. 72 911E 2.7 RS stuff 72 911T with a 2.7(Sold 5-13-2011) 2012 Kona Blue Metallic Mustang GT Convertible 6spd 67 Mustang coupe future SVRA group 6 car 63 Falcon hardtop 302/4spd |
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03-11-2004, 06:05 PM
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1973 Porsche 911 2.4 MFI
