Threaded inserts for exhaust?

[Dinky26]

Anybody ever try these on an EA81 exhaust?

Need to drill out with a 31/64 bit first. Is this going to make the walls of the bolt holes to thin? The tap needed for them is a 9/16-12 tap, just wondering if that is going to compromise the holes.

Edited October 1, 2014 by Dinky26

[stratman977]

I have 1, I have been waiting to put into my ea82. I had a helicoil in there but I think I drilled the hole a little off because the helicoil threads didn't tap out too well. Theres a little for it to grab but not much. I am going to see if sleeve retainer will be enough to hold it before it put that thread insert in.

 

For what its worth I think it will work just fine but I don't want to drill the head with the engine in the car laying on my back under it so I didn't throw it in there yet. Don't know about the ea81 though.

[rdweninger]

The existing threads are 10mm x 1.25    So 10mm in decimal inch is .39"  which is just smaller than 13/32".   The Heli-coil kit comes with a 13/32" drill bit... which is just larger than the existing hole... and will accommodate the new tap and threads for Heli-Coil brand.

  Your 'new' studs require a 9/16" hole and drill bit... which is just over an 1/8" larger than the 13/32" required.

Personally, I would not drill out my heads with 9/16".   That is way too excessive in my opinion.  You're losing a lot of material that you cannot replace!  Ever.

I used Keenserts (stainless) on my heads. Google them.   Then used the stock 10mm x 1.25 studs (new, of course).   I don't remember the drill required, but they will tell you when you order the insert for 10mm x 1.25.   It is probably a numbered bit very close to 13/32"

[idosubaru]

that's a standard repair done by many people on here.  there's threads about it - and widely available studs with standard oversize thread on one side and the metric exhaust size on the other.  i'd search for the detailed threads on here about it. 

[Dinky26]

I've actually ended up just drilling into the extensions on the heads, I could only get the tap in so far, I probably should have taken them off, I didn't want to mess with tying to get those star bolts out though.

[stratman977]

The max major diameter of a m10x1.25 is 9.972mm (.3926in) and the max major diameter of 9/16-12unc is 0.5609. It's basically only an 85 mil increase per side which isn't a whole lot. The major diameter of a helicoil thread is proprietary but I'd guess it's about 1/2 way between the virgin thread and the 9/16-12. To me it doesn't look like its going to be a problem if you never have to remove that insert but it's really your last chance on the hole without welding.

 

I would use a helicoil or use a time sert before I went with one of these but you can install these for less than $15 compared to $50+ for a helicoil kit or a timesert kit.

[Dinky26]

I'll let you know how this works out once I get the gaskets in.

 

I put her back together tonight, just no gaskets to go in. They'll be here in the morning.

 

It is quieter now without gaskets than it was before I started this venture ..

[Gloyale]

Run a 7/16th tap right into the stripped hole.

 

Install 7/16ths stud and nut (11/16th nut, so 17mm socket still works)

 

Done.  And you've still got room for a helicoil if you ever strip it again.....which you won't.

 

 

*note* buy new nuts w/17mm outer for the remaining metric studs...then you can still use one socket for all exhaust.

[TomRhere]

Yep, 7/16 tap works great, no drilling involved. Leaves plenty of meat around hole for heli-coil later if one decides to do so.

 

Works most excellent if it's one of the long studs that go thru the spacer block on EA81 engines, as you only need to tap threads in it, not the head. Done that many times.

[Dinky26]

Cool, many THANKS people.