When the MGA Twin Cam was in production, the factory was dealing with a large number of warranty claims. They eventually offered the customers an exchange 1600 pushrod engine in place of the original twin cam engine, and there is a factory directive explaining how to do this. Below is a copy of a page from David Knowles’ book. There was an 18 page factory document covering the conversion to pushrod using service kit 48G157 dated March 3, 1960. David also lists two cars that were converted by the factory as a test of the kit. They would be listed in production records as Twin Cam with the appropriate Twin Cam chassis numbers. If these cars still exist, they may have the 1600cc pushrod engine number stamped on the Car No. plate. This offer for transplant would have continued until the warranty expired for the last twin Cam produced, and may have been performed at customer expense after the warranty expired. Click on the image below for a larger image.

Now the search can proceed for documentation of the 48G157 Service Kit, and the two cars that were converted at the factory. It is odd that there was no Confidential Service Memorandum directing the dealer service shops to do this under warranty.