Thursday, 13 December 2012


It's a shame that the comments facility on Google blogspot attracts mainly spammers.  Nothing malicious, just some automated system that sends positive anonymous comments to probably millions of blogs simultaneously in the hope that we will be flattered and might reciprocate, thus increasing their viewing numbers.  I can only guess that the motive is financial, linked to some dodgy advertising income.  Deleting this rubbish is time consuming, so comments for the time being are de-activated.  Get a grip Google!

One serious shortcoming in every old car I've ever owned has been the heaters inability to live up to it's name.  I've resolved the problem in my 140 fixed head by fitting a Mazda MX5 Matrix and blower unit.  It works at least 5 times better than the original but I feel could still be improved on.
My requirement for the 120 is in a different league.  I'm not too bothered about de-misting but on cold days the heater will need to send out a constant blast of really hot air to keep me, and in particular my legs (which are invariably cold) toasty warm. 
As the car wasn't fitted with a heater of any kind, my only constraint is to try to make whatever I fit, appear reasonably similar to the optional equipment item. I also want it to work a good deal better than some of the modern after market heaters currently available. 
So, two areas to consider - first is as big a matrix as I can possibly accommodate in the very limited space available and second is a a multi-speed blower, capable of shifting serious amounts of air through the heater matrix. 
There is absolutely no point in having a matrix filled with slow moving warm water, and that I believe, is a major reason why many old car heaters are so poor.  The colder the day, the less heat they appear to produce.  I think (hope) the solution to this is to use an electric booster pump (EBP).

Bosch Heater Pump with PWM control.  Just need to hide
the knob under the dash.
This will work in conjunction with my electric water pump conversion (see post 42).  The heater will have (when required) first call on the hot water supply, with the main water pump, radiator and fan topping up the cooling as and when required.  As with the main water pump, the heater booster pump will have pulse width modulation (PWM) control to set its speed, effectively allowing control of the temperature in the matrix. 

My interpretation of how this will look and work with both
Electric Water Pump (EWP) and Electric Booster Pump (EBP)
shown.  The graph relates to the EWP control only.
The matrix needs to be enclosed in a box mounted on the engine side of the bulkhead with it's output passing to the other side, the passenger compartment just above the gearbox cover, more or less as the original heater.  The largest unit I can find that will fit comes from Car Builder Solutions and measures 8" x 5" x 2" high.  It also has its pipes running in the right direction for what I think will make for a neat installation.

£48.00 Heater Matrix from Car Builder Solutions
The worst part of the job is tackled first.  Not that it's difficult, but I hate cutting holes regardless of necessity.  It makes me feel a little better to know that this one is in the same place as the original would have been if the optional heater had been fitted, just a slightly different shape.

Hole for Heater Matrix output cut in bulkhead
Next I need to work out the design of the enclosure.  Air will be pushed into the top of the matrix from a blower which will be mounted under the passenger wing in a 140 style battery box.  The hot air will come out of the heater matrix into the cabin from two 3" vents, each with rocking and rotating vanes to direct the flow.  It may even be possible to fit an original heater cover over these (if I can find one)

Draw it first, half the fun, if like me you enjoy that sort of thing,
but still leaves some elements of 'making it up as you go along'

The enclosure is made from 1.5mm Aluminium sheet, cut, bent and riveted together.  Isopon sealed the joints airtight and high temperature silicone fixed the matrix in place and ensured no leakage between the input and output chambers. On completion, to check for leakage, I submerged it in water to see if any air bubbles emerged - none.

Inside of enclosure with chamber divider Araldited in place
Years ago I borrowed and used some cracking good and very clever 'sprung' rivets to temporarily hold sheets of aluminium together, mainly to allow accurate drilling of additional holes, but also to allow easy dismantling and de-burring before final assembly.  I lent the kit to someone and you can guess the rest.  I saw something almost identical advertised (again Car Builder Solutions) but under the brand name of 'Cleko'.  I bought the base kit, insertion tool and 10 1/8 inch Clekos and they were once again indispensable.

Side of heater matrix enclosure temporarily 'cleko'd' together.
Happy with the matrix enclosure, I give it a roughing up in my blast cabinet to ensure good paint adhesion, before applying a few coats of satin black to match the rest of the engine compartment.

Finished enclosure - Air inlet sits below bulkhead and has 4Nr
3/16 UNF inserts araldited on to allow fixing of 63mm flange
for flexible pipe from blower.

Water in / out side of enclosure

Finally in place on the bulkhead.  Just needs a couple of Smiths
Heater labels to fool all but the most astute XK aficionados.
The rivets will hopefully be less obvious without the camera flash.
The second part of the installation, the blower, to be ensconced under the passenger wing will be completed in February and finally, the booster pump and plumbing after the engine is re-installed, probably in April. 

Whilst I optimistically hope this will produce all the heat I could ever ask for, I am aware that it is at this stage mainly theoretical - The proof of the pudding etc.
My glass remains as ever, more than half full!!!

Rear wings and doors - Trial fit
Having secured the body to the chassis and carefully and continually checked the door gap measurement between two datum points, it's time to trial fit the rear wings and doors, just to ensure nothing major has occurred during the process. 
I also have the wing beading made up by the trim man so this is also trial fitted. Alex and Niel from Auto-Bodycraft arrive 7.00am prompt and spend a couple of hours hanging the doors and setting the gaps back up. Door and wing fit turns out to be as good as I have seen anywhere. The beading still needs a little 'tweaking'.

Doors will be taken off again to prevent damage, but I now
know for certain that the gaps and fit are excellent. 
Thanks to Alex and Niel at Auto-Bodycraft
Visitors invariably comment on the general tidiness of the workshop, but in reality they don't see the real mess it gets into on occasions.  I usually call a halt when I can't find things anymore.

Halfway through the heater enclosure job.  Picture proves that
it's not quite as organised as it sometimes seems.
Next Post Early January 2013