Once I had pulled the heater out of the Vogue I discovered that the heater core I was planning to use was not going to fit. The Vogue heater is 230mm wide and 83mm deep. The extra depth I thought I had, is taken up with a duct that runs up the back for the window demister.
Here is the original water heated core in the heater box.
The ceramic heater core out of the Heller heater is 91mm at it's narrowest dimension so it doesn't fit. I played around with trying it on different angles but nothing really worked very well.
This is the ceramic heater core as it started life.
Enter my trusty hacksaw, then a tube of high temperature RTV silicon (red high temperature gasket maker from SuperCheap auto, rated to 315 degrees C). Now it's about 215mm wide and 45mm deep (I'm calling it deep because that kind of how it fits in the heater box). The aluminium section is 200mm wide - the lugs add an extra 7mm either side. This new shape lends itself better to the airflow through the heater box as well. I removed all the spade terminal lugs and remounted them 90 degrees to give better clearance to the sides of the heater box. I had to use the old ones as they were stainless steel and since they were mounting on aluminium, I figured that I shouldn't use copper lugs. The center (top to bottom) sections of aluminium are joined (left to right) under the silicon mess in the middle to minimize wiring.
Next I made up a little timber frame 228mm x 83mm (internal). An old number plate surround (strange the things you keep) provided a perfect profile for mounting the core once it's finished. I cut the surround to make 2 of 225mm aluminium strips.
Here, the core is ready to complete "potting". I will use a tube of clear RTV silicon I already have to finish it. The clear stuff is only rated to 230 degrees C but that should be fine. (Hmm, the tube I "had" is as solid as a rock. Seems it doesn't last 10 odd years - even unopened.) That will have to be the subject of another post.