Installing Compufire
 

My 2 litre 1973 model now has the above installed.
When I did the BTDC timing with the vacuum hoses off and plugged the mark would not line up with the fixed point.
Performance wasn't great either.
I then timed it with hoses connected and got closer to the mark,performance was good.
It puzzles me why time the ignition with vacuum hoses disconnected when that's not the setup when driving the car?
Must be missing something here?

You time it with the hoses disconnected because you are measuring the timing with all of the centrifugal-only adjustment in. That's why you set it at 3500 RPM--the centrifugal advance should be all in by about 3000, but you go over just to be sure.

Twist the distributor until the 27 deg BTDC mark lines up with the notch in the observation hole in the fan shroud when the hoses are off and the engine is at 3500 RPM.

You can see where the timing lands when you have the hoses connected, but that will change depending on the throttle position and the exact vacuum level in the manifold.

--DD

Is it critical to plug the disconnected hoses ?
Thanks for the info.

In an L-jet car, it is. The mixture in a D-jet car does not get changed much by vacuum leaks, so it is not critical to plug the hoses. Don't leave them disconnected, though, and don't put them down into a pile of dirt or anything you wouldn't want to get sucked into the engine.

It is a good habit to plug the hoses when you disconnect them (in case you wind up working on an L-jet car or carbureted) but not critical on D-jet.

--DD

Thanks Dave,I took the car for a run and it was sluggish,back in the garage I timed to hoses disconnected but unplugged,the dizzy had to be turned roughly half an inch counter clockwise,close to timed spot on.Car ran like a rocket,Hallelujah.
Only prob now is the plug to Temp sensor one has a broken wire resulting in fast idle,meaning mixture controls are at minimum.
Is there a quick fix to soldering that plug wire?