[Mgs] MGA 180 out Distributor Mystery

PaulHunt73 paulhunt73 at virginmedia.com
Sun Oct 21 04:19:34 MDT 2012

As the points weren't opening on the original distributor, that was the 
original problem.  You then fitted several distributors.  If you didn't 
remove the plug leads from either the plugs or the original cap (did you 
reuse that with each of the replacement distributors?) then the assembly of 
the rotor and the drive shaft of the original distributor was 180 degrees 
different to the others you tried.

Whether it is right now or not is another matter.  Static timing with the 
pulley mark by the appropriate pointer will show the points opening when 
No.1 *or* No.4 pistons are at TDC, but only one of those will be on its 
*compression* stroke.  You determine that by removing the plug from No.1 
cylinder, putting your thumb over the hole, and turning the engine until 
compression pushes your thumb off, then turn to TDC.  If the rotor is now 
pointing to about 2 o'clock, then either drive gear and distributor assembly 
are both correct, or both 180 degrees out.  If it's pointing to about 8 
o'clock then one or other is 180 degrees out.  Whether it is worth doing 
anything about it is another matter.


----- Original Message ----- 
> ... Two sets of newly installed points would not open when fully
> adjusted out.  A club member suggested that the distributor bearing was
> wearing out. I took the 1800's original 25D distributor and base clamp
> and installed it.  ... I got used another DM2 with the same result.  I 
> installed a new Lucas 25D, same
> result. Then I switched the wires replacing #1 with #4 and # 2 and # 3
> figuring it was 180 out.  Bingo, it purred like a kitten.  Mystery.  How
> could the distributor drive gear get 180 out when I never touched it? 

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