MFI - warped throttle bodies - seek advice

[jkeyzer]

Finally got around to working on the 911 a while this evening. Eurometrix advised putting a pane of glass against each individual throttle body to check for warpage causing air leaks. Well, I did it, and the bad news is that they are indeed warped. A PO (I plead innocent) most likely tightened them down too much and warped the flanges for each individual TB (one is even cracked). I very roughly measured the bowing to be 0.01" worst case, and it is visible to the naked eye upon close inspection of the flanges.

Seeking advice on a fix. Amateur machinist friend suggested sanding both TB banks against a known flat surface and if that fails milling them flat. Any potential pitfalls with milling away a small amount to make them flat? Cheap fix would be to use gasket goop but I am doubtful.

Thanks. I'll have this thing put back together someday.

[Bobboloo]

Take them to a machine shop and get them resurfaced. I don't think it will cost much. They do this to heads all the time.

Also make sure they're good and clean before reinstalling.

Bobby

[jkeyzer]

One more question, is this stuff weldable? I want to have the cracked flange filled in before machining.

[Bobboloo]

I would think so. They would just need to know what kind of metal it is. My guess is that it's magnesium but thats just a guess. I've heard of people welding the magnesium fan housings so it should be doable.

Bobby

[jkeyzer]

Does anyone else know if these are magnesium or aluminum?

[pwd72s]

Jeff, I've heard they can be either metal...but a good machinist should know by looking...color & weight.

[jkeyzer]

Thanks guys. A friend has offered to do the work at no cost so I may take him up on it.

Otherwise if anyone knows of a good machine shop here in SD I will look into it. Kurt or Rich?

[jkeyzer]

Turns out mine are indeed magnesium. Unless anyone has had success welding these, they appear not to be an alloy that can be welded.

I had everything resurfaced by a friend who ended up just using a flat machined surface and sandpaper. It turns out the plastic stacks were also not flat so I had him fix those as well. I think it's time for me to invest in an in-lb torque wrench and some new nylock nuts and washers. I know I've asked this before but does anyone have a torque spec for the TBs to heads and stacks to TBs? I can't find it here but I don't have the factory manuals.

Leaks between the TB and head may explain why #1 plug always seemed to look leaner than the rest.