Timing marks

[DarnPB]

Need help on what ignition timing marks to look for on my 91 8v digi. Just had the engine apart to replace the rings and then went to set it up. The Haynes is as clear as mud, so I set the timing to what I thought were the ignition timing marks, a ´0´ on the flywheel, which I assumed was TDC, and a groove before it, which I assumed was the timing mark. But the engine ran horribly. Hunting idle, mis firing, the works. So I retarded it by sound and got it running a whole lot better, but I want it right.
BTW, what is the timing angle BTDC?

[richard s]

if u line the cam marks up. remove dizzy cap and line notch up with centre of rotor arm then take the green plug out of the gearbox when crank is spun to tdc you will see a notch in the flywheel. line these three marks up and your timing is done

[DarnPB]

But surely that is to find TDC to make sure everything is where it should be prior to any engine tuning isn´t it? Not for final ignition timing with a strobe? The book says that strobe timing should be at 2000-2500 engine rpm. But I´m confused which timing marks to set up by.

[takethefifth]

I havn't done it myself but i believe the large mark is TDC and the timing mark is 6 degrees BTDC.  Hope thats of some help. 

[rubjonny]

you need to use the big arrow mark, but it must be set at 2.25k rpm, when the engine oil is over 80degs, with the blue sender disconnected on a digifant!  Check my digifant tuning guide in the how-to child forums, this tells you everything you need to know to get a digi running sweet as a nut

[DarnPB]

Thanks. I did this as per you said, but could not get it to run right and the emissions were off the chart. Had to retard the ignition timing significantly to make it driveable.
I´ll have another go this weekend.

[rubjonny]

once you change the ignition timing you'll probablky need to adjust the idle & CO as well!
Worth replacing the blue temp sensor also...

[...joe]

i think you need to go back and re-check all the timing marks are where they should be. you can get it pretty close by using the pulley's as a guide as the cam pulley should have a mark, the bottom two pulleys have a notch and a mark, which will get them pretty close then check for the notch on the flywheel and the position of the rotor arm on the dizzy. then go from there. not doubting your skills but if its running that bad something is amiss. it should be running pretty spot on before final tuning using rubjonny's guide.

[DarnPB]

All this started a couple of months ago when I opened up a thread ¨Digifant systems¨.
I had emissions that were off the scale and worn rings were diagnosed. I tore the engine down and found that the bores were so glazed, you could have shaved with them. I check gapped the old rings and they were well out of serviceable limits. I dimentioned the bores and they were ok, so I just fitted new rings, and glaze busted the bores. I was maticulous in reassembling the engine and getting the marks all lined up, and they are spot on. Engine started first turn of the key, albeit roughly.Got it so that it was driveable and drove it for about 800km. (500Miles) Then went to set it all up and it just won´t come right. The blue sensor is new. That was the first thing I went for when it failed the ITV. (Spanish MOT) Set up the timing to the marks that are described both here and the haynes and drove it. The engine had power, but the idle was hunting and the on a run, the engine was miss firing. I went to set up the mixture and idle as per instructions on this site and also referring to the haynes, but could not get the emissions down below 8. Anyway, I got the engine running better by audibly adjusting the timing retarded. Then had to go north for work. I will have another go this weekend, but I do need some ideas of where I have possibly gone wrong.
Thanks for the replies.

[rubjonny]

Was it a VW sensor, the pattern ones are rubbish.  Also check the idle switch, throttle cable & stop adjustment as if these are out it will throw everything off.
Another thing tio try is another AFM, as these get older the spring looses tension and throws everything off too.