porting throttle body.......how much off!?

[hyland770]

today i set about cleaning my throttle body inside and out...... great success!
then after that thought i may as well have a go at porting it, so i got the correct drill and drill bit out and started sanding down the sides of the throttle body above the butterfly, but then realised i had no idea how much to grind out!!?
i searched in the search section and on none of the diy's does it say how much to take out!
so what im wondering is how much do i want to grind out?
do i want the walls of the t/b to be really thin and thus the hole bigger (if you know what i mean)
if someone could post some before and after pics of theirs so i know what im trying to achieve that would be a massive help...
p.s. i realise this would be best with pics but its dark outside and i didnt take any at the time, im guessin you know what im on about as a lot of you have already done this mod!

[Khare]

at the bottom on the front there is a large hump, remove that.

At the top, on the back there is a bigger hump, remove that too. Job done 

[hyland770]

i was trying to find these humps and couldnt see any, maybe its already been done!? 

[Khare]

i was trying to find these humps and couldnt see any, maybe its already been done!? 

You must see them....post some pics.

[VW BUSH]

Front at polishing stage

Back at polishing stage

More front 

Back with core shut off highlighted with cutter

[axewielder]

just smooth off the steps as much as poss, you want smooth transitions, just dont take it off where the butterfly is when shut or youll get dodgy idle like khare

[Horney]

Knife edge the butterfly and fill and smooth the screws in the butterfly shaft while you're at it.

nick

[Baskey]

Is it worth doing? Iv found keeping them clean is vital on these engines but does going to the trouble of polishing them help the engines performance??

[Khare]

Knife edge the butterfly and fill and smooth the screws in the butterfly shaft while you're at it.

nick

Don't.

I learnt the hard way. Scrappy hunting tomorrow for a new one 

As DH said, it wont make much difference if you knife edge it, yet it can cause so much trouble.

[Horney]

Knife edge the butterfly and fill and smooth the screws in the butterfly shaft while you're at it.

nick

Don't.

I learnt the hard way. Scrappy hunting tomorrow for a new one 

As DH said, it wont make much difference if you knife edge it, yet it can cause so much trouble.

Yes if you do it badly and try on a spare one not one you actually need! I've done this to loads of carbs and 2 of my MKII golfs but always picked up a spare TB or carb and done it on that then fitted it. I need to pick up one for the current MKII to do.

nick