Even though the previous owner had bought a new electronic distributor – it was one that was advertised would fit any year of manufacture. That didn’t sound right as many different distributors were fitted to the cars as the engine specs were changed over the period of their manufacture.
The performance of the car seemed to flatten over a certain revs so i thought i would get a distributor that was specified for my year / vin which i found off eBay – date stamped 1075 (week no – year no) so definitely the correct era for a 1975 motor,
Cleaned it up, new springs and vacuum advance swopped the electronic ignition parts to replace the contacts and refitted and retimed. I was able to check that the engine revs and advance roughly confirmed to the correct advance curve i had found online – see below.
A noticeable improvement with the benefit of electronic ignition performing to the correct advance curve shown in the picture.
When you see the range of curves across the mgb years – see http://www.mgb-stuff.org.uk/curvestext.htm (a great informative website) – how can one distributor fit all. Add onto this vacuum curves as well then it is even more important to get the right part. Of course i guess ask this changes if the engine is tuned in any way – these are for factory engines.