I should clarify: the round end of the ball-pein hammer or screwdriver handle is used very gently - enough to make a crease in the underside of the gasket material. Use of the vise is just to keep the part steady.

Though I have used the ball-peen method I never liked it.  I worry I'll damage the parts by using the hammer.  

Instead, I prefer to place the part (t-stat housing) on a sheet of gasket paper and use pencil to trace the perimeter and the mounting holes.  After cutting out the perimeter with scissors I use a hole punch to make the mounting bolt holes (a little on the tight side).  Then I place the un-finished gasket on the t-stat housing and use bolts to align the paper with the part.  A quick series of short cuts with an X-Acto knife completes the gasket. YMMV  

All that being said, when I recently wanted to make a couple of gaskets I had to spray my roll of gasket paper with WD-40 and let it sit for a while to "soften up".  It had been sitting on the shelf so long it felt like it was going to crack just from unrolling it.

+1 !!

If you have never cut a gasket, the easy way to mark the gasket material for cutting is to place the T'stat housing in a vise (after cleaning it) with the mating surface up. hold the gasket material snugly over the surface and very gently tap with a small ball-pein hammer or the rounded end of a screwdriver handle to gently emboss the housing holes into the gasket sheet. I like to do the mounting holes first, then cut them out and use 3 bolts to keep it in position before doing the main opening. If your housing is in good shape, you can also mark out the exterior profile.

I use a Mr. Gasket thermostat...last year instatesd a Gates...did NOT open at 190 F.

I have no idea about the gasket.  I always cut my own from gasket paper.

Thanks! That will make the trip easier :)

Good to know Doug, is the gasket the same also?

The later Midget t-stat also work, even those for the 1500.  

I think 74 is the last year a Midget stat will work. In 75 they switched over to the Triumph 1500 engine for emission purposes i am not sure if that one is interchangeable.

Small block Chevy t'stats work, or one for a mid 70's Midget.  And while you're at the local parts store, buy some gasket material and make your own.

73 MG Midget thermostat and gasket will work.
The GM thermostat is the one used in a small block 350 cu in Chevy but the gasket won't work.

Hi There. I remember a discussion years ago about equivalent Thermostats for use in classic Minis. I vaguely recall a certain GM thermostat and gasket fit.. does anyone recall this? I'd rather go to the local parts store and grab one as opposed to having to order online.