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sjwright944

Cylinder Head Exhaust Manifold Stud replacement

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Hi all,

I need to rebuild my cylinder heads, and not surprisingly, virtually every exhaust manifold stud sheared.

I've spoken to a handful of machine shops, they will drill or mill out and helicoil, one mentioned using spark erosion to remove the studs to try to save the threads.

What's the opinion on the best method? I understand the original design was just threaded holes with no inserts, but working in aerospace, I don't see the problem with helicoils.

Any experience shared would be appreciated.

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If many of us can drill out broken exhaust studs without damaging the threads, laying on our back under the car with a hand drill, it will be a breeze with heads under a pillar drill.

Have a search for various post on on it.

Mark

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12 hours ago, SilverWT said:

If many of us can drill out broken exhaust studs without damaging the threads, laying on our back under the car with a hand drill, it will be a breeze with heads under a pillar drill.

Have a search for various post on on it.

Mark

I’m with Mark. I’ve just done seven studs on my neighbours 89 Turbo and the job is easy with care and the right technique.  A good central centre punch, small pilot hole and then gradually enlarge out to the core diameter.  Then gently use a tap set to clear out the remaining thread.  He did have some very good, sharp Milwaukee drills which helped a lot.  They now sell them in Screwfix

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^^^+1 I did several lying on my back in sub-zero temperatures using a cordless drill. Saved all of the threads. It would be a piece of cake with the engine on a stand. Slow and steady wins the race ;)

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I was thinking more of helicoil versus trying to save the threads. Did a load of searching and they seem to be very anti-helicoil over on the Pelican forum.

I've drilled out studs before, and was trying to save time, but you guys have given me the inspiration. I will get a second hand pillar drill and get onto it.

Thanks for your replies.

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Not sure how a pillar drill is going to help, you can't put the engine under that?

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33 minutes ago, Phill said:

Not sure how a pillar drill is going to help, you can't put the engine under that?

The heads are all off and stripped.

Hence the desire to get it done asap. Getting fed up with it being in pieces now. Need to drive it! 

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Fair enough but you could do it with a cordless drill easily enough. A pillar drill will come in handy for other things too though.

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Time sert if necessary after drilling the old stud out. Any good machine shop should turn that around pretty fast

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19 hours ago, Phill said:

Fair enough but you could do it with a cordless drill easily enough. A pillar drill will come in handy for other things too though.

This was how I did but I did have my friend keeping an eye on the angle of the drill from another side to ensure it went down the middle.  So if you decide to use a hand drill see if someone can help ensure you get the drill straight

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And buy some top quality brand new drill bits to do the job with. 

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