Herald 13/60 advance/retard curve or table

[Adrian Girling]

I'm considering building my own electronic ignition using hall sensors which is fairly simple but I'm wondering about using a MAP sensor and RPM to advance the ignition electronically rather than the original vaccum and inertia approach.  A throttle position sensor could provide additional data and bring the spark timing near the optimal achieved by modern ECUs

Does anyone know where I can find the advance/retard data for the original distributor?  The stationary advance is 9 degrees.  By locking the mechanical advance my concern is that the rotor arm contact angle may not be sufficient to accommodate the required range.

Thought I'd mention, for anyone thinking this is crazy, maybe it is, but I always like to challenge the conventional. I know there are perfectly good solutions available in the market, and there is not much wrong with the standard distributor.

[Nick Jones]

There are some listed here,

http://www.teglerizer.com/mgstuff/advance_curves.htm

but maybe not yours. Suggest googling the specific distributor number.

The curve won’t necessarily be right for modern fuels anyway.

There is considerable benefit to be had from a decent 3D ignition system WRT to torque spread, driveability and economy.

[Adrian Girling]

1 hour ago, Nick Jones said:

The curve won’t necessarily be right for modern fuels anyway.

Thanks Nick, interesting table.  Doesn't include the Herald but the range is probably something similar.  And googling has taught me that modern fuels need different curves so the standard distributor may be seriously sub-optimal and your point about 3D systems expresses my general thoughts nicely.  Getting it to work may not too difficult, but fine tuning will likely need a rolling road dynamometer.

[Nick Jones]

On the original version of Vitesse EFI, where the bottom end of the engine was still factory, I set the initial timing table up using the  numbers from the original distributor "Map".  I did mess about with the part throttle settings very considerably, especially at lower rpms, and it was surprising how much timing could be put in without bad things happening.  In fact, in some areas I took timing out purely to make the driving experience smoother (too much torque response to small throttle movements!).  This was the equivalent of messing about with the vacuum advance.

I never messed with the "top line" though.  That is, the full throttle line, or in mechanical distributor terms, mechanical advance only.  I did eventually go to a rolling road, where, amongst other things, we checking the full throttle timing numbers and found that they were still good.  The most fun part was setting up the part throttle advance in the cruising areas.  Set the RR to hold rpm, tap the timing numbers up until the torque peaks and starts to go back down, then back off to just short of the peak.  Did this on my PI as well.  Both cars were very fuel efficient.  

I have somewhat messed this up with the new ITB setup - goes just as well, even a bit better in places (much more tractable low down), but some economy has been lost.  Time to visit the RR again.

[Adrian Girling]

13 hours ago, Nick Jones said:

On the original version of Vitesse EFI, where the bottom end of the engine was still factory, I set the initial timing table up using the  numbers from the original distributor "Map".  I did mess about with the part throttle settings very considerably, especially at lower rpms, and it was surprising how much timing could be put in without bad things happening.  In fact, in some areas I took timing out purely to make the driving experience smoother (too much torque response to small throttle movements!).  This was the equivalent of messing about with the vacuum advance.

I never messed with the "top line" though.  That is, the full throttle line, or in mechanical distributor terms, mechanical advance only.  I did eventually go to a rolling road, where, amongst other things, we checking the full throttle timing numbers and found that they were still good.  The most fun part was setting up the part throttle advance in the cruising areas.  Set the RR to hold rpm, tap the timing numbers up until the torque peaks and starts to go back down, then back off to just short of the peak.  Did this on my PI as well.  Both cars were very fuel efficient.  

I have somewhat messed this up with the new ITB setup - goes just as well, even a bit better in places (much more tractable low down), but some economy has been lost.  Time to visit the RR again.

Many thanks Nick, I'm learning from your knowledge and experience.  Checking the rotor dimensions it does look like the rotor arm arc is easily big enough to make good contact with the cap HT contacts over these angles with a locked distributor - looked marginal until I remembered, it only has to cope with half the advance angle.

Although I'm also considering using a wasted spark coil pack with built in driver which is relatively inexpensive and electronically easy to implement.  Can't think of a reason why not, but I'm ready to be shot down on this....

[Nick Jones]

Wasted spark coil pack with built-in coil driver is the way to go IMO.

I binned the Vitesse distributor in 2005…..

[Adrian Girling]

2 hours ago, Nick Jones said:

Wasted spark coil pack with built-in coil driver is the way to go IMO.

I binned the Vitesse distributor in 2005…..

Excellent!  I will follow your lead 👍

[Adrian Girling]

Should have thought of this before.  Some advice on how to attach a crank trigger wheel?  And mounting the trigger sensor - I'm thinking of fabricating a bracket to bolt onto the plate which extends out to the left of the engine (as you look from the front) which is there for the engine mount....

[drofgum]

Adrian,

I attached the trigger wheel to the engine side of the crank pulley. For the sensor I built a bracket that bridged across the timing cover, using two of the cover mounting bolt holes. I used long bolts and spacers to get the sensor in line with the trigger wheel. There were slotted holes to allow adjustment of clearance.

The attached pic shows how it was done.

Cheers,

Paul

[Adrian Girling]

1 hour ago, drofgum said:

The attached pic shows how it was done.

Very nice Paul, thank you 😀

[Nick Jones]

Pics from my son's MkIV running EFI and wasted spark ignition via Speeduino ECU

Trigger wheel

Sensor

Absence of distributor and coil pack hiding on the bulkhead.  Coil pack is VAG one with built in ignitors.  Avoid the cheap ones......

The squirty side.