MIG & Lathe Ported TB
MIG & Lathe Ported TB Well I finally got around to porting my TB since I had Vets day off. I decided to do mine differently; chucked it up on the lathe and bored it out that way, and also machined the front half of the shaft off. Instead of filling it with epoxy, I welded it in with the MIG welder, then put it back on the lathe and milled the two holes for PCV and IAC. I also bored out the IAC port to get more air in to help with cold idle. Just thought I would post all this so people with these tools would know about another method of doing it. I'm sure the performance is no different than the grind and glue method.
I was surprised how big that bump is just before the throttle plate! I took out a lot of metal here. When I removed the throttle shaft, I noticed that it's supported by a pair of sealed ball bearings; this is a nice design.
While welding, I had to pause frequently to avoid overheating the ball bearings.
I was surprised how big that bump is just before the throttle plate! I took out a lot of metal here. When I removed the throttle shaft, I noticed that it's supported by a pair of sealed ball bearings; this is a nice design.
While welding, I had to pause frequently to avoid overheating the ball bearings. Last edited by Cal; Nov 12, 2003 at 11:35 AM.
Yeah that's basically the same thing we do.
You have to bore the lip out because you will not get it all by hand. The only problem with MIG welding, or any welding of the TB is the heat. The heat needed to cure the powdercoat on the TB is not bad, but the heat from welding will easily cook the bearings. Not saying it can't be done but it's a big risk since those things are a bastard to get out of the TB. Plus just filling in the viod in the TB is not all that the epxoy is good for. It really does help to have the epxoy around that to help with flow.
BTW I know all of this because I have welded up throttle bodies in the shop.
Bret
You have to bore the lip out because you will not get it all by hand. The only problem with MIG welding, or any welding of the TB is the heat. The heat needed to cure the powdercoat on the TB is not bad, but the heat from welding will easily cook the bearings. Not saying it can't be done but it's a big risk since those things are a bastard to get out of the TB. Plus just filling in the viod in the TB is not all that the epxoy is good for. It really does help to have the epxoy around that to help with flow.
BTW I know all of this because I have welded up throttle bodies in the shop.
Bret
Yeah I was a little concerned about cooking the bearings also, so I paused frequently and let it cool (and squirted a little cooling water on the bearing area from time to time.) This took a while to do, but then on the other hand there was no waiting for epoxy to set up doing it this way. The bearings were still moving smoothly when I got done, and the rubber/plastic bearing shields were intact. I got the shaft out pretty easy, but I could see the bearings were sweged (sp?) in.
I did end up with the outer rim of the air horn bulged out after the welding; but a light cut on the lathe restored it to better roundness than stock. Only problem there was I had to dial it in first with a four-jaw chuck since the air horn is not concentric with the throat bore.
I ran the boring bar through once parallel to the bore to get the hump out, then a second time with the compound on an angle to follow the bell shape of the air horn. (damn air horn is asymetrical as I'm sure you know!) After welding it, I made the same two passes with the boring bar to clean it up. I also used an end mill rather than a drill bit to make the port holes to get a smooth cut through the curved surface. Another thing I did was over bore the IAC seat a little to improve my cold idle. I noticed the IAC plunger is a cone shape, so you can get away with this. All in all the way I did it was probably more work, but I like the results. Sorry no pics; I was in a big rush to get the TB finished and back on my car.
Bret, I'm impressed that you guys machine the lip out; I just assumed everybody did it with a grinder by hand.
I did end up with the outer rim of the air horn bulged out after the welding; but a light cut on the lathe restored it to better roundness than stock. Only problem there was I had to dial it in first with a four-jaw chuck since the air horn is not concentric with the throat bore.
I ran the boring bar through once parallel to the bore to get the hump out, then a second time with the compound on an angle to follow the bell shape of the air horn. (damn air horn is asymetrical as I'm sure you know!) After welding it, I made the same two passes with the boring bar to clean it up. I also used an end mill rather than a drill bit to make the port holes to get a smooth cut through the curved surface. Another thing I did was over bore the IAC seat a little to improve my cold idle. I noticed the IAC plunger is a cone shape, so you can get away with this. All in all the way I did it was probably more work, but I like the results. Sorry no pics; I was in a big rush to get the TB finished and back on my car.
Bret, I'm impressed that you guys machine the lip out; I just assumed everybody did it with a grinder by hand.
Originally Posted by Cal
Yeah I was a little concerned about cooking the bearings also, so I paused frequently and let it cool (and squirted a little cooling water on the bearing area from time to time.) This took a while to do, but then on the other hand there was no waiting for epoxy to set up doing it this way. The bearings were still moving smoothly when I got done, and the rubber/plastic bearing shields were intact. I got the shaft out pretty easy, but I could see the bearings were sweged (sp?) in.
Originally Posted by Cal
I did end up with the outer rim of the air horn bulged out after the welding; but a light cut on the lathe restored it to better roundness than stock. Only problem there was I had to dial it in first with a four-jaw chuck since the air horn is not concentric with the throat bore.
Originally Posted by Cal
I ran the boring bar through once parallel to the bore to get the hump out, then a second time with the compound on an angle to follow the bell shape of the air horn. (damn air horn is asymetrical as I'm sure you know!) After welding it, I made the same two passes with the boring bar to clean it up. I also used an end mill rather than a drill bit to make the port holes to get a smooth cut through the curved surface. Another thing I did was over bore the IAC seat a little to improve my cold idle. I noticed the IAC plunger is a cone shape, so you can get away with this. All in all the way I did it was probably more work, but I like the results. Sorry no pics; I was in a big rush to get the TB finished and back on my car.
Originally Posted by Cal
Bret, I'm impressed that you guys machine the lip out; I just assumed everybody did it with a grinder by hand.
Bret
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Originally Posted by SStrokerAce
Nope, I do as many things by machine as I can. The throttle stop is all done by machine also. Some of the work has to be done by hand, and the final shape of the TB is done by hand.
Bret
Bret
After doing all this, I must say the price charged for having it done is very fair. But still, there is a certain satisfaction to having done it yourself. My hands were black with aluminum well before I was done, and that was another reason I didn't take any pictures along the way, I didn't want to even touch the camera with those hands!
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Originally Posted by Cal
You're right, I still had to blend the area where the two lathe cuts intersected by hand. I used an air die grinder with a stone then switched to a flap wheel to smooth things out.
After doing all this, I must say the price charged for having it done is very fair. But still, there is a certain satisfaction to having done it yourself. My hands were black with aluminum well before I was done, and that was another reason I didn't take any pictures along the way, I didn't want to even touch the camera with those hands!
After doing all this, I must say the price charged for having it done is very fair. But still, there is a certain satisfaction to having done it yourself. My hands were black with aluminum well before I was done, and that was another reason I didn't take any pictures along the way, I didn't want to even touch the camera with those hands!
It's dirty work. Add epoxy into the equation and it's a heath hazzard!
BTW we have a special on ported TB's right now with no core charge! $200 takes everything, and that's awesome considering that core charges are normally $200.
Bret