Tuesday, September 2, 2014

Distributor and tuning

The weekend Nora got a timing tuneup.  Although Nora is a '41 she has the engine from a later model Plymouth.  The engine number begins with a P22 so it either a '51 or '52.  Many of the parts are still interchangeable nonetheless.

Tuning parameters for 1949 to 1952 U.S.-built Plymouths (P-17, P-18, P-19, P-20, P-22, P-23)
  • Spark plug gap - .035"
  • Breaker gap - .020"
  • Initial ignition timing - T.D.C.
  • Dwell setting - 34.5 deg. to 38 deg.
  • Firing Order - 1-5-3-6-2-4
Once I had an idea of the engine model I was able to order the proper points, condenser, distributor cap and rotor. Although initially I set the points to exacting precision, ended up adjusting the dwell but guess and ear.  Same goes for the timing, I started off at TDC (top dead centre) then had to adjust the timing slightly after the engine was warm. 
Internals of a IAT-4003 Autolite Distributor.
I suppose there was supposed to be a conical gasket between the engine and distributor so I fashioned one  from a couple layers of fibre gasket material and gasket goo.   I seems to work as well and didn't leak any oil after a 30min drive.

An artist rendering of a Distributor for a P22 engine.
After about a year driving on the old points and condenser set-up.  I swapped them out for an electronic ignition from Pertronix.  The model for my distributor and 6 volt positive ground was the 1362P.
Drilling out the rivets on the advance plate.  Won't be needing that any more.
The after removing the post, the pick-up screwed into place on the advance plate.  A magnetic ring slips on under the wiper.


Pick-up and magnetic ring.
This points replacement is a huge improvement.  The engine starts better, runs smoother, and has way more power.  Hundred bucks well spent.