Triumph Repair: 74 Spitfire Timing, compression stroke, spitfire 1500

Question
I have a 74 spitfire 1500 that I am finishing up the rebuild on.  I had a local machine shop assemble the short block.  When I picked the motor up I realized the distributer gear was in 180 degrees from what my shop manual said was the correct position.  I rotated the disturber gear to the correct position.  I now have the engine back in the car and have realized when trying to set the static timing that the rotor is pointing to the #4 spark plug lead when the notch on the crank is 180 degrees from the recommended timing position.   Shouldn’t the rotor be pointing to the #1 plug wire while in this position?  Does this mean that my cam is timed 180 off?

Answer
Wes,

There is a 2:1 ratio on the Cam to crank gears.  So when the crank is at #1 TDC the ignition rotor can be in 1 of two locations, 180 degrees out.

What you need to do is crank the engine over by hand and watch the valve timing to verify TDC for ignition.  Keep in mind that the cycle is Intake, compress, igntion downstroke, exhaust.

So when you see the intake open then both valves close the engine is going into the compression stroke.  At TDC (plus or minus a few degrees based on the distributor timing) it's time for #1 to fire.  

That's where you should align the distributor/plug leads to.


Cheers,

Jim