A Odd Mi16 Conversion Fault

[Miles 331 1 Cars]

After yet another 16v transplant and getting the car MOT'd the other day I'd thought I'd give the car a very small blip going along the road, Then thats where it got a bit odd as I heard pinking of all things which is completly new to me on one of these so when I got back to the workshop I got the old vacume guage out and it showed the advance to be too much, so a couple of mins of head scratching and the first port of call was the TDC sensor which turned out to be the cause of this,

So one to watch out for

[pip470 61]

what was wrong with the tdc sensor, did you change it? And then it was fine?

[Mikey G 3]

So how do you check the ignition timing with a vac gauge?....

[Miles 331 1 Cars]

Yes the TDC sensor was faulty, replaced it with the later style one and all good

 

On the vacume guage it's got marked segments on it, The guage must be a good 40 tr's old but still works a treat

[Mikey G 3]

I think you have misunderstood my question. In what relation does vacuum pressure make to an ignition system that has no vacuum advance in the system as surely vacuum pressure bears no visible relation to physical ignition timing? Unless of course you are getting some sort of preignition that is pulsing positive pressure back into the intake manifold?

 

Sorry to be a bit pedantic, but i have never heard of anyone who has used a vac gauge to diagnose an ignition timing fault. I can understand that a bit of advance and retard can affect idle speed so in that respect manifold pressure could be up or down to maintain a preset idle speed, am i barking up the right tree here?