Scooterotica

I'm rebuilding a Jet200 motor and would like to get the case vapour blasted.

The cylinder studs are well tight - I've heated the casing with both an air gun and then a blow torch but they haven't budged no matter how much I swing off the spanner.

I'm wary of using anymore force in case I break something!

Any suggestions - diesel soak?

Chemodex Penol is very good if left to soak.

You might think I am crazy but what I do is, after soaking them and heating them up very well, hold the bare casing with your right hand and then put the rebelious stud on the vise. Make the vise tight and carefully start twisting the casing 360º. It has not failed me once. Now, you have to be extremely careful and it is much better if you have a mate helping you. The key is in the heat that you apply, previous to start twisting. Just a thought...

Kind regards,

Jaime

Presumably you have tried double nutting. There is always the possibility or the treads stripping out from the alloy if they are so tight in 50+ year old castings. Inter-crystaline corrosion and all that.
You mention heating, but maybe trying a few heating cycles will do the trick, with a splash of antiseize while hot, (this is best done out side).
Are you using a propane torch or a hairdryer thing? Maybe it just didn't get hot enough, but remember aluminium melts at 660C, and anneals at 300C. You can get wax sticks that indicate how hot a surface is or an infra red thremometer. Spit begins to bead off at about the right temp.
If you are really desperate they must come out, run a bead of weld just above the gasket face, a spritz of your chosen anti seize won't come amiss. Allow the heat to penetrate, then use a big fookoff pair of stilsons as close to the gasket face as possible. Repeat if no movement. Press and relax, press and relax, press and relax.
The studs I used to have to get out were shorter, so I'd weld a big nut over the end, worked everytime.
Don't break the studs off, and if you do, don't try stud extractors, anything that tight won't come out, straight to a spark eroder. Or cut out the stud and reweld and machine back.
You'll need new studs afterwards.
You could cover the studs with tubing, I used old nylon air line. Cut to length, ends square, washer and old nut on top.

if you can get the double nut method to hold the stud clamp the casing to a bench so that it is firm and then apply pressure on the stud with a ratchet and socket and then apply some heat to the area you may feel it give slightly if not try tightening it up even further this may just allow some give for you to start rocking it back and forth going a little more each time the studs are long and applying force evenly and squarely is a problem as it tends to buckle and put pressure unevenly on a thread the shorter the stud the more squarely you will be able apply pressure so POSSIBLY cutting the stud down to approx 50mm and then welding a nut on might be an option the problem with heating is that a hole expands three dimensionally and can if overheated clamp around the other object

heat then get some nitrogen and freeze them for the nitrogen supply i use computer key board cleaner, wilkinsons (the shop that sells crappy plastic things and paint) sell it for 2 quid a can,hold can upside down and spray it. the nitrogen propellent comes out at about minus 20 and the frost is instant,,,do not test it on your skin to find out how cold it gets ! !.. expansion then contraction,,you get the picture !,,it works

Leave them in I reckon !just mask them up before it gets blasted

Dean

swizz wrote:heat then get some nitrogen and freeze them for the nitrogen supply i use computer key board cleaner, wilkinsons (the shop that sells crappy plastic things and paint) sell it for 2 quid a can,hold can upside down and spray it. the nitrogen propellent comes out at about minus 20 and the frost is instant,,,do not test it on your skin to find out how cold it gets ! !.. expansion then contraction,,you get the picture !,,it works

Halfrauds sell "shock unlock" that does the same thing.... Plenty heat, then blast it to get lubricant down the hole.... leave, heat and remove.....

Thanks for the tips fella's...

yes just leave them in situ ,no probs