Club 80-90 Forums

That my dizzy seems to have its TDC mark in the wrong place. I mean the little mark on the dizzy housing which should point to 3 oclock ish where no 1 HT lead is.

The little read line is where the mark is


Or is that just a guide and as long as my rotor arm is on or just before no 1 ht lead at TDC on the pully?

Im only asking as my dizzy is electronic and was wondering if it thought that the mark should be over no 1 ht lead.

I also cant see any other way of putting it in as the vacumn unit would be in the way. I brought this dizzy secondhand from mega bug and they said it was the right one.

Ongoing crisis

If it runs and can be rotated to time correctly, then that's the main criterion, then if the lead splays make sense as far as neat routing (no crossing)...

But as far as it being the correct one, that really is down to the vacuum and centrifugal adv/ret ccurves inbuilt.. many aftermarket dizzies are supposedly OK, and engine will run, but not uncommon that some combination of economy/performance is compromised, usually economy for performance...

If it idles reliably, picks-up & runs smoothly,doesn't pink excessively or detonate at all, gives acceptable economy and performance without hesitation, then...

OK thanks that what I thought

I timed it by hand to 5 btdc. It wouldnt start before but it now starts on the button, it just overheats (other threads and i know I am really boring people now)

Need to strobe it now, might still be out hence overheating.

Cheers

And its this pinking and detonating that I have never really understood. It does sound a little link a machine gun

Sounds like it's too far advanced....also could try 98 ron which would minimise the pinking as it has a higher resistance to ingniting.

Martin

Red Westie wrote:Sounds like it's too far advanced....also could try 98 ron which would minimise the pinking as it has a higher resistance to ingniting.

Martin

Yeah need a stobey on it me thinks

Overheating can lead to pinking... which is usually associated with over-advancement (pinking is)

Overly retarded can cause overheating, not overly advanced

Hope that makes sense...

e.g. First make sure it isn't overheating for lack of cooling, or other reasons...
Its rare for an engine to be that retarded and able to be driven hard enough to overheat, but can happen.. basically the overheating due to too much retard would be exhaust valves burning first of all (popping back), high cylinder temps not necessarily reflected in the coolant temp

disi has been rebuilt and reassembled incorrectly me thinks, HacksawBob's was the same, made it hard to set up from the mark
5 degrees advance is correct for unleaded on 1.9 and 2.1
10 degrees on a DJ running superplus

I'm running 7-8 degrees for lpg, still ok on petrol, on MV running unleaded

his van is Aircooled aiden

jason k wrote:his van is Aircooled aiden

That it is

It does look like the dizzy has been rebuilt though, becuase it would be impossible to fit any other way becuase the airbox would get in the way of the vacumn unit

Cheers

HarryMann wrote:Overheating can lead to pinking... which is usually associated with over-advancement (pinking is)

Overly retarded can cause overheating, not overly advanced

Hope that makes sense...

e.g. First make sure it isn't overheating for lack of cooling, or other reasons...
Its rare for an engine to be that retarded and able to be driven hard enough to overheat, but can happen.. basically the overheating due to too much retard would be exhaust valves burning first of all (popping back), high cylinder temps not necessarily reflected in the coolant temp

Thats intresting becuase on type2.com its reconed that to far advanced causes over heating

No lack of cooling, flaps are fine, all tinware in palce and sealed

Thats interesting because on type2.com its reconed that to far advanced causes over heating

That's a very common misconception, or rather oft quoted synaptic copy & paste of someone else saying it... only believe 50% of what you see and 25% of what you read and 10% of what you hear

It also seems true in a way, because the symptons can be like overheating, which can bring on pinking if not high-speed detonation itself

That is, both over-advancement and over-heating mitigate towards pinking and/or detonation, but the former does not automatically lead to the latter...

Whereas excessively retarded ignition can lead to overheating and is classically known to, for very good reasons... the charge burn is delayed and can still be burning as the exhaust valve opens (risking burning the valve) and this poor exhaust stroke reduces scavenging efficiency, the fresh (cool) inlet charge is thus polluted (and heated) before it has even been compressed; round the wheel of (mis)fortune we go, with more & more heat building up in the main cylinder area...
The misconception also lies in the fact that retarding often (not always) makes an engine lacklustre and wooly, so isn't pushed, possibly won't rev well, and, well you get it, isn't lickely to overheat seriously, but per cycle, more heat is being put into the coolant (& thermal efficiency goes down). It might also pull quite wellat low/medium rpm... (might!, hard & fast often come with lots of caveats)

Light pinking (tinkling) from a slighly low octane or 'on the edge' advancement setting, doesn't really add much heat, although high speed detonation can easily strip any protective boundary layer from the combustion chamber, putting more heat into the walls and the piston crown (shockwave effect), but by the time this is seen as a coolant-tempreature rise, the game would normally be all over!