Setting The Distro Timing

[shalmaneser 26]

I'd like to have a play with the setting on the distributor as I think I'm missing a bit of top end. The car's brilliant up to about 6K but it starts to feel a bit breathless afterwards. Obviously I'm going to check the state of the vacuum advance diaphragm at the same time, but I'd like to get a good setup before I start fiddling with the vacuum bit.

 

It's the first time I've had a play with the ignition timing, what am i looking for? I guess the danger is 'knocking' at lower engine speeds, what conditions are likely to promote this sort of behaviour? I guess WOT at low revs in high gear? I've marked the currant position so if it all goes tits up i know where to go.

 

If i advance the timing a tiny bit every day until i get these symptoms and then back it off a touch will that confirm i've got the timing set up right?

 

And if worse comes to worse and my vacuum advance unit is gone (i'll try the suck it and see test) can I get a new diaphragm or is it a complete replacement?

 

Cheers for the help!

 

Adam.

Edited April 26, 2010 by shalmaneser

[Baz 421]

Yes basically as you've put it, listen out for pinking under load, like marbles being hit against each other, it should be pretty prominent with the windows down etc! When you find it doing so, back it off a little so it stops.

 

Tbh it really depends how you drive, i never drive under load in a high gear, say 30mph in fifth and full throttle, so if it does it then, it doesn't bother me as i'll never do that etc, i tend to test it as i'd drive it, then a little more/'worse', and set it to around there.

[The Arch Bishop 0]

The vaccum units are complete units but are not too bad price wise. Recent thread for part numbers etc here.

[Anthony 1,003]

To do it properly, you ideally need a rolling road.

 

However, the method you describe seems to work quite well for standard(ish) engines - fill up with the fuel you're planning to run, and then keep advancing the dizzy until it begins to pink between 2000-3000rpm at WOT, then knock it back a touch. Certainly that's how I've "tuned" the ignition advance on most of my 8v's, and they've all been pretty quick and given good fuel economy for what that's worth.

 

You'll likely need to adjust the idle speed after any changes, as more advance usually increases the idle speed.

 

However, it's also entirely feasable that you just have a poor/average 1.6 engine and that's why it's flat at high revs - I've driven lots, and there's a massive difference in performance between them. Could be that there's an issue somewhere as well - clogged fuel filter, poor ignition componants, worn cam, incorrect cam timing etc.

[shalmaneser 26]

Thanks for the input!

 

Will have a fiddle and see what happens - I don't really tend to labour the engine at all, I guess that's the legacy of learning to drive in a 55 bhp micra - I'm happy to stir the gearbox a bit!

 

It certainly feels like a good engine, she pulls strongly well past 90 (on a private road!) but I'd like to have tinker and see if i can squeeze any more horses out.