Best way to get heat exchanger studs out of the heads?
 

Subject says it all. All of the heat exchanger studs are really rusty and probably pretty weak. The all look like these two:

http://forums.pelicanparts.com/uploa...1066397005.jpg

I was thinking of just trying to double nut them and unscrew them out of the head. Should I heat them up first? All suggestions appreciated!

Try heating the aluminum around the stud, and use a good stud extractor. If you are removing the heads anyway, may want to have a machine shop mill it out or even better, EDM it out.

I have been there done that.....

Chris

Kurt,

Since I assume you are going to send all of the heads off to have the valve guides and valves done ... why not just let the pros replace all of the studs? EDM would be my preference, but not that many shops are equipped to do that on 911 heads.

You may want to talk to CE, EBS, and German Precision before making the final decision as to who gets the heads. Then, again, John Walker could probably do all of them in one afternoon! I know that 'Super' Jim was impressed with John's work!

Use the blue wrench.

What is EDM?

leave them alone, or you're going to create a lot of work for someone, maybe you. they get glass beaded during the cleanup process, and probably will be ok. if they're broken or rusted to the point that there are no threads to speak of, then you replace them. i use a drill jig to deal with them when needed. there's too much chance of screwing up the head by drilling off-center otherwise.

The man has spoken! Heed those words.

John as you already know these heads are going to you to work your magic on them! I'll let you deal with the studs, thanks!

Rick,

EDM is Electro-Disharge Machining ... basically, the reverse of plating! Mini-sparks in a dielectric fluid blast away at the offending broken part at a microscopic level with a precisely-ftiting tool that is guided slowly down [or up] through the center of the stud, leaving a few shards of thread to be picked out ... threads in the base-metal casting are unaffected. Wayne's rebuild book mentions a specially-designed machine that fits under a 911 engine on a hoist ... that can remove single broken studs in place! It takes an hour or two for the sparks to do their thing!

Amazing! Thanks for the description Warren.

I am indeed impressed with John's skill and I place great value on his advice. Warren's too, BTW. Even before reading John's suggestions, I formed the opinion that those studs are probably best left alone. They will not "play nice" if someone tries to remove them. I think there is no penalty for ignoring them until one snaps. My suspicion is that the accessible part of the stud serves no purpose in removing them. I suspect they cannot come out except by drilling or EDM.

I too am very impressed with John's skill and knowledge and his willingness to share his knowledge with us. 3 years ago he sent me, at no charge, a throttle rod I needed on an MFI. I'm sure it was no big deal to him, he probably doesn't even remember doing it, but it sure meant a lot to me. I don't forget things like that. I could easily drive to Kansas City or St. Louis to have some stranger work on my heads, but I feel much more comfortable boxing up the heads and shipping them off to John!