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timing!

Ive just gone through my Lucas dizzy on the 86 V12 which seemed to be lacking in centrifugal advance.

I found that the large spring was stretched so that it sat loose on its pins. Full advance just started to stretch it. It was probably giving far too much advance.

I crushed it back short with vice vice grips and got it back to what I assume is normal length. It is barely loose on the pins. Any motion and it comes into contact with both. It's very strong. Now the CAdv turns smoothly half its max travel then the second spring makes it quite difficult to turn the remainder of its stroke.

VAdv disconnected and plugged I ran her at 3000rpm and checked the timing. Should be set to 18 per my sticker. It was at 28. Retard the dizzy as far as it will go and I get it down to 24. I literally can't reduce it further as the VAdv capsule is hard against plug A4.

Trst drive shows no power at all. Dog slow and weak. Twist the dizzy clockwise and she starts to sound better, drives right, chirps the tires if I goose her. No detonation I can detect.

What is is going on here? It's like I have something completely wrong. She prefers somewhere around 28 BTDC at idle with VAdv connected.

My distributor reads...
42640A
36DM12
​​​​​​​1086

No chance this is the wrong part for my car is there? What could be making me so far off spec for the timing?

I have not confirmed the timing gauge on the motor is dead accurate yet, but it cannot have an adjustment range of 10 degrees in those slots can it? It's just ludicrously off.

 

A few things ring little bells in the empty head.

The timing plate can be out by 12deg.

The timing mark on the front pulley can also be out by any amount as the rubber that holds it where it belongs delaminates, very common.

#1A plug OUT, rotate the enguine, BY HAND (NOT THE STARTER MOTOR), and when compression air is felt coming out that hole, insert a soft wire probe, and FEEL the piston rising, and STOP when it gets to TDC. NOW check the mark under the front, and maybe make your own marks for now.

Rotate that engine again, BY HAND, almost 2 full turns, and STOP when the NEW mark under the front is at 10BTDC.

DO NOT ROTATE THIS ENGINE BACKWARDS, SOOOOOO, IF YOU GO PAST THE TIMING POINT, GO AROUIND 2 MORE TURNS AND PAY MORE ATTENTION TO WHAT YOU ARE DOING.

Set the distributor at this point with the micro at the FULL retard position.

As I mentioned before, I reckon the time has come to reset that distributor in its hole so the vac unit is pointing much more to the inner bit of the throttle pedastal. This jamming against #4A is really getting in the way.

My internet is still blistering along at 18kb/s, so I will attempt to add a file, haha.

Refitting the V12 distributor.pdf

 

Also, once those springs are damaged, they are throw away.

You will not reset them to the original spec, I have tried many times.

The V12 distributor is teh V12 distributor.

With NO Marelli engines, there are 2 units, PreHE and HE. Mine runs a PreHE base and HE top section, The PreHE has 3deg more mechanical advance, which is what I want.

 

Well, there's your problem right there!

TDC is at 10 BTDC on the gauge. I went through the procedure you provided and now she's running like, like, well, like a V12 Jaguar!

I did not move the dizzy a tooth. It was all the way retarded on the mounting slots so I rotated it's position clockwise and, combined with the change to the centrifugal advance, and the timing change, it's not in conflict with my plugs any longer.

One note. I assume the deviation on the gauge is because of moment of the pully with the "1A" timing mark on it. There is no way that the gauge on this model can be adjusted. It doesn't appear to have slots at it's mounting, and even if it did movement laterally would cause contact with the pully as it wraps around it very tightly.

So, do I need to replace that pully? Is this the "Harmonic damper"?

Here's a pic of the gauge.