By Corky Guenther
As you may remember, our 1967 MK1 (MK1 designation is not formal but is consequential) Chrome Bumper MGB is undergoing an extensive refresh. Part of that refresh is to add Air Conditioning. I read a lot, had some conversations with Dean who has done one or two in various cars and perused the MG Experience where the discussions ranged from “Why would you do that? - If God (or BMC) – etc.” through, “I did it with pieces from eBay or other sources” to “I bought a kit”. Except for those who deem it a sacrilege to depart from the factory delivered configuration (not sure how they capture the factory delivered air when new tires are required), the majority opinions were positive with some observations about effectiveness in Tourers vs. GTs.
So, I sallied forth and, not being a thermodynamics engineer (if that is the right field) or any other kind for that matter, and thus not wanting to attempt to piece meal a solution, ordered a kit. The kit includes all the requisite parts, compressor, condenser, dryer, evaporator, bulk hoses with fittings, vents and bulk air hose, controls, and brackets for all the components. Should be a “bolt in and press on”. Well, not quite. It is kind of like trying to put 12 pounds of stuff in a 10-pound bag except in this case it is probably 7.5 pounds of stuff in a 10-pound bag. The problem is the shape of the stuff and the shape of the bag.
This discussion deals with mounting the AC compressor and alternator. The kit provides a set of brackets to mount both. First, to mount the supplied compressor bracket requires some trimming of the engine mount, not significant, done. After that, I bolted the compressor mounting bracket in place then mounted the compressor and the alternator on its brackets.
About this time, I started down a Rabbit Hole chasing the powering of only the compressor with the belt from the crankshaft. The water pump with fan and the alternator being powered by a belt from the second pulley of the compressor. This with the intent to lessen the strain on the water pump bearings. Because this is a MK1, the radiator top hose is on the right-hand side of the car which limits the space available for mounting the alternator above the compressor. This reduces the wrap of the belt on the compressor second pulley casting doubt on the ability to drive the alternator. Starting in 1968, the MK2 onwards the top radiator hose was on the left. So, I climbed out of that hole.
To the situation at hand then. After remounting the compressor and alternator following the kit instructions using the supplied brackets, it became clear that the alternator would come afoul of the upper radiator hose. I asked for photos of AC in MK1 and the only one I received utilized a radiator with the top hose on the left-hand side of the car. I tried several configurations of the supplied brackets mounting the alternator positioned outboard of the compressor. The result was insufficient space to run the AC and oil cooler hoses.
When I started this project, I had downloaded a copy of the instructions for the previously offered Moss kit. Referring to those I found that they used a set of brackets that mount the compressor closer to the block additionally using a bracket that is designed to mount an alternator when replacing the generator. They also mount the compressor further forward than the kit supplied brackets. Mounting the compressor further forward requires rerouting of the oil cooler hoses and the use of pre-bent hard lines to the condenser and drier. Not an option. So, I ordered the alternator bracket and set about fabricating a set of brackets using the Moss brackets as a pattern. To mount the compressor in the rearward position, I split the forward bracket into two pieces. One to attach the compressor to the generator pivot point on the water pump and the second to provide adjustment capability. The rear compressor bracket is the same as the front. To save time (and steel) I prototyped brackets using plywood. I found that I can make drawings using Microsoft Paint. I chose a scale of 1024 pixels per inch to easily subdivide into decimal and fractional measurements. Then, I opened the .bmp file with Photoshop Elements and resized the image to 1024 pixels per inch. There may be more efficient programs, but this is what I have. The result is printing a full-size accurate pattern which I attached to the plywood using double sided tape and cut out using a band saw. Holes with a drill press, slot started with multiple holes and completed with a rat-tail and flat/half-round files. I used a lot of plywood. Each iteration took a couple of hours so a lot of time too. The alternator mounting brackets were another iterative process. At the end, I have a set of four with adjustable tensioning brackets which I think will work. I’m not going to render them in steel which will take some time, until I have mocked up and routed the hoses. Another perfectly good two-hour task. Shouldn’t take more than a week – maybe two.
