[Mgs] MGA 180 out Distributor Mystery

Clayton Kirkwood crk at godblessthe.us
Mon Oct 22 17:40:37 MDT 2012

Correct me if I am wrong please, but it seems the only reason to set the
distributor up "right" with the rotor pointing to the 1st cylinder (1
oclock) is so that everybody does it the same way and nobody gets confused
like this. If the distributor is 180 degrees out, one only need change the
wires around. In fact, you could technically put the distributor in in any
orientation and as long as you get cyl 1 tdc on the compression stroke and
turn the distributor body to line up the rotor with the cyl 1 ignition wire
you would be ok. Of course, you may have problems with the vacuum advance
alignment but that is a different story. I think it basically comes down to
everybody agreeing to one convention like driving on the left side of the
road is wrong:>)


-----Original Message-----
From: mgs-bounces at autox.team.net [mailto:mgs-bounces at autox.team.net] On
Behalf Of PaulHunt73
Sent: Sunday, October 21, 2012 3:20 AM
To: Robert J. Guinness; MG List
Subject: Re: [Mgs] MGA 180 out Distributor Mystery

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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