A distributer question on the 1275 engine.

[DavidApp]

Having got the engine finished and on a stand I have been trying to get it started.
It has a 25D distributer and I believe the wrong distributer cap. The TR3 cap and the MG cap look like there is a 90 degree difference in the plug wire location. I will be ordering a new cap from Moss. At the moment it has the TR3 cap and I made allowance for that when I connected the plug wires.
I have the distributer drive set with the slot at about 7 and 2 with the slot below the center line. With the engine set at TDC on No.1 cylinder on the compression stroke the rotor arm is pointing to the 7 o clock position. I thought it should point more to 3 o clock. Could the drive dog on the distributer be in the wrong position?

It has fired and almost run a couple of times.

David

 

[JPSmit]

Congrats David - sounds like you are very close. I know that with the 1275 you can mount the distributer 190 deg out - but then you would have nothing.

Others smarter than me can come along but, with the 4 cylinder cap as long as it fits it should be fine - 90 degrees apart is 90 degrees apart. Similarly, the 'position' is relative to the piston and not to the engine. So the plug wire to piston one could be in any of the four positions as long as the spark gets there in time.

When I was where you were with Ms Triss, I had someone turning the key while I gently moved the distributer a few degrees forwards and backwards - and suddenly it caught. Then, once it had caught I used the timing light to find the sweet spot.

Good luck and keep us posted!

 

[DrEntropy]

David, as long as you have the firing order correct at the cap and the cap and rotor are made to be together, the position of the dizzy really has little to do with it. You say on #1 compression (TDC) the rotor points to 7 o'clock in relation to the engine? Use that as #1 firing by using a 12V static light. Should be close enough to get it running. Rotor turns counter-clockwise, BTW. So #3 firing would be in the 4 o'clock area.

As for the drive gear from the camshaft, it does sound like that is out of the "traditional" position. This is from a Haynes manual for the MGB (closest to hand) of the position but should be the same for the 1275:

 

[DavidApp]

The drive gear is in approximately that location. My clock must have been tilted a bit.

I have got it to fire a couple of times but not run.

I notice that the rotor does not point to plug wire contact in the cap when the points open. It is almost halfway between contacts.
Looking at the setup on my TR3A at TDC on No.1 the points are just open and the rotor cap is aligned with the No. 1 plug contact in the cap.

David

 

[bobhustead]

The body of the dist needs to be rotated so that the rotor is pointed pretty much at the distributor electrode you are trying to energize, i.e., the one connected to the spark plug that needs to fire.
Bob

 

[DavidApp]

Unfortunately I have no idea of the history of this car. It was not running when I got it and who knows what had been done to it.
On the distributer I found the drive dog was 180 degrees off. I corrected that.
I noticed the spark seemed very weak despite having new points correctly set, new copper plug wires, new plugs correctly set and a new condenser.
Full disclosure I did connect the battery +ve to the the distributer instead of the coil for a second. Brain fart. Big spark.
As the internal wire from the coil to the points took the brunt of the error I replaced that wire.
I check when it fired using a plug in No.1 plug lead and confirmed No. 1 cylinder was at TDC on compression stroke.
Spark still seemed very weak so I replaced the condenser and got a couple of very short runs out of it.'

As the engine is on a stand I plan to rig up a choke and throttle control and see if I can get it to run properly.

The photos show the drive with No.1 Cylinder at TDC compression stroke and the position of the rotor arm before I changed the drive dog.

 

[DavidApp]

It seems to start easier now.? Things get settled in with the first few starts?

Need to rig up the radiator so I can run it for a while while it is on the stand.

David

 

[DrEntropy]

It seems to start easier now.? Things get settled in with the first few starts?

Need to rig up the radiator so I can run it for a while while it is on the stand.

David

Just remember to account for torque if you plan to rev it much!