Further to the brief note in the editorial, here is a more detailed explanation which was provided by Trad Harrison.
The after-market parts originally featured in the editorial in the August 2011 TTT 2 and reproduced here are thought to have been produced by Runyan, LA in the 1950s, possibly intended for the TD. Two of these parts were fitted to a cast aluminium tappet cover plate, which was highly polished and looked quite good. Customising was much in vogue at the time!
Because of the two vents, an improvement was claimed for crankcase breathing (re- oil being pressured out past the crank scroll). However, this claim was not really proven and Trad reckons that Abingdon knew what they were doing with their cheap pressed steel plate and the single pipe tracking directly down into the airflow beneath the car. The stock arrangement would have had the advantage of a certain amount of suction.
TF Clock – Polarity
A reader, who bought a clock/mile counter from a Y-type for the missing one on his TF was told by his watchmaker that the instrument was negative earth.
I asked Barrie Jones, the ‘T’ Register Technical Specialist for the TD and TF models, about this and here is his reply:
“The TF clock has always puzzled me. It clearly says POSITIVE EARTH on the casing, but I cannot see anything inside that is polarity sensitive.
I do know that a Y-type clock will work in a TF. I also know that both the TF and the Y-type were wired for POSITIVE EARTH.
I would do a bench test by connecting the clock to a 12 volt car battery. Firstly, connect the casing of the clock to the negative side of the battery, and supply a positive power supply. If it works OK, then try connecting it the other way around. Observe the reciprocating balance wheel as it goes round. Does it make a big spark, and is the spark brighter when connected the wrong way around? If it seems OK, fit it to the car”.
And finally… A useful contact for clock (and other instrument repairs) is John Ostick in Keighley, West Yorkshire (01535) 672125 – website jdo1.com