Rear heat exchanger studs 71 squareback

[Jared1969]

Hi all. I have a new exhaust (vintage speed) for my 71 SB. I've had a look at the studs holding the rear heat exchangers in and my gut feeling is they are going to snap. I've had this issue before with my bay and have drilled out and re tapped no problems. However is it possible if they do snap to drill and tap with the engine in situ? I'm apprehensive to start the job as I don't want to remove the engine if possible.

[937carrera]

To avoid snapping them can you get access to oxy-acetylene to provide sufficient heat to allow them to be removed in one piece?

[broady_6]

if you cant get a gas axe. A few options, take it for a drive get it nice and hot and try to work the nuts back and forth. Obviously be careful around a hot engine. A nut splitter my work, but space it tight. (I'm assuming but rear nuts your actually referring to the nuts on the front of the engine. The two which hold the heat exchangers to the head at the flywheel end?)

Another less fun option is a good old cold steel chisel to split the nuts. If it looks that bad though I would personally remove the engine to enable me to remove the complete stud from the head and put new studs in. If they look like theyre going to shear off, I wouldn't use them to fit my new exhaust

[purplepeter]

I very much doubt You'll be able to either get a drill in there or succeed in drilling it out squarely...Sorry!
If You really stuff it up though, it's possible to overdrill it & slip an M8 Nut in between the fins

[Jared1969]

Thanks as I thought, something so simple becoming a major job. Engine out it is then.

[937carrera]

Why not put some decent penetrating oil on and allow it to soak at least overnight, then try before you drop the engine ?

[Jared1969]

Yep done that this morning will do again over the next couple of days as want to do next week when my barn is emptied. Wanted to get plus gas, but found some stuff that Edd China has endorsed from Halfords. Will let you know if it works.

[s.unsworth]

Confused about Back and Front. Rear Heat Exchanger Studs to me would be for the Secondary Heat Exchangers i.e nearest to the Rear of the car. When I did my rebuild all the Stud Nuts came undone OK except for one on the Front Right ( Main ) Heat Exchanger. Felt like it was coming undone like all the others but it snapped off flush with the Cylinder Head. I managed to drill that one out lying on my back under the Variant. I used a Timesert Kit ( USA). That includes a special Drill, Tap, Countersink Bit, Insert and Tool to screw the Insert into the newly tapped oversize hole. Then a new standard size Stud of course. That was about 7 years ago, and it is still OK now.

[Jared1969]

Thanks have been soaking the the four nuts daily. And taking into barn on Tuesday to try and remove. If they snap it's engine I reckon but with everything clear and out of the way I may just have a fighting chance of doing.

Thanks