MG Car Club of South Australia
MGC NEWS MGC conversations by Richard Mixture, April 2017
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A Supercharged Story
ello again, it’ s Richard here with supercharged story. You might remember last month’ s story about the‘ MGCs Down Under’ book that that nice young Register Co-ordinator is writing describing MGC in New Zealand and Australia. Well he passed on a note to me about this young fella, John Caffin, whose been racing MGs since the late 1950s when he started racing a MG TD that was supercharged. John, found it easy to maintain and very reliable. So, what better thing to do but supercharge an MGC.
John has been involved in historic racing for most of his life and has raced many different cars including a Ferrari, a Lotus Elite and a Cooper Climax with a 2 litre, twin cam engine. He decided to return to supercharging a car and chose a car with a roof but found he had a bit of a barrier with his Director General of Indoor Duties. Here’ s what the note said;
“ I had purchased a GEN3 M90 Eaton supercharger on E Bay and at the time I was negotiating to buy a Porsche 912 with the intention of supercharging it. This was the 4 cyl model based on the VW. In the early 1970’ s two of these had been supercharged here in Melbourne and they were very successful according to the Porsche Distributor who had told me about them. The only problem I had was my wife did not want a Porsche with a roof on it, see wanted another MG. There just happened to be rust free
28 automatic C Type Roadster for sale here so that’ s just what we purchased.
The C Type didn’ t require much examination to see that there would be no problem accommodating the M90. There were two bolt holes in the bottom left hand side of the block to locate the belt adjuster pulley and to support the front of the supercharger. The harmonic balancer also had 4 tapped holes where the air pump pulley was mounted( for North American MGCs), so there was no problem with the crankshaft Pulley.
I fabricated the manifold out of 1.6mm steel tubing clamped to a large piece of C section steel to avoid distortion. I bored the holes in the C section using an exhaust manifold gasket to locate the flanges for the head. Initially I made the carburettor to supercharger manifold to suite a single 2” SU. It was just not up to the job and it was replaced by twin 1¾” HIF6 SU’ s. Which are easy to tune.”
After sorting out a few teething problems John was out for a run in his white MGC when he noticed a flash from flames trying to escape from under the bonnet. Fortunately he had a small fire extinguisher so he popped the bonnet open and squirted it at the flames. The flames were reduced until, unfortunately, the extinguisher was empty and they were back with vengeance. I’ m sure you can imagine what happened while John waited 20 minutes until the fire brigade arrived. It was back to square one!