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 !