Some ignition advice please ?
Discussion
Hi,
Recently bought a Tiger kit car with 2.0 Pinto running Kawasaki carbs and a kent camb, with standard coil and dizzy.
I looked at the timing yesterday and found it to be about 6 degrees advanced beyond the 8 Deg BTDC as reccomended in the Sierra manual i.e. 14 degrees BTDC.
I put it back to the 8 Deg BTDC and it runs well, but start to "cough" around 3000rpm and backfies quite a lot when lifting off the accelerator when changing down.
I now realised that the dizzy has no vacuum advance pipe connected.
So the question is - did the prior owner advance the ignition because there is no vac-advance connected to the dizzy - so should I put it back to what it was.
However, will this not harm the engine (long term).
OR, connect up a vac-advance pipe from the inlet manifold ???
Advice gratefully receieved.
Cheers
Recently bought a Tiger kit car with 2.0 Pinto running Kawasaki carbs and a kent camb, with standard coil and dizzy.
I looked at the timing yesterday and found it to be about 6 degrees advanced beyond the 8 Deg BTDC as reccomended in the Sierra manual i.e. 14 degrees BTDC.
I put it back to the 8 Deg BTDC and it runs well, but start to "cough" around 3000rpm and backfies quite a lot when lifting off the accelerator when changing down.
I now realised that the dizzy has no vacuum advance pipe connected.
So the question is - did the prior owner advance the ignition because there is no vac-advance connected to the dizzy - so should I put it back to what it was.
However, will this not harm the engine (long term).
OR, connect up a vac-advance pipe from the inlet manifold ???
Advice gratefully receieved.
Cheers
The vac advance is for economy, track cars don't bother with it.
The best way to set it up is to run as much advance as you can without the engine pinking. Remember fuels are different now to when your engine was produced and because it's modified you cannot rely on the factory specs. A rolling road set up would be the most accurate however.
The best way to set it up is to run as much advance as you can without the engine pinking. Remember fuels are different now to when your engine was produced and because it's modified you cannot rely on the factory specs. A rolling road set up would be the most accurate however.
You can't expect the ignition advance for the standard engine to be applicable to to one with a performance cam shaft and bike carbs fitted - both static advance and the advance curve requirements will have changed. You should ideally run with some kind of engine load sensing since this will significantly improve part throttle economy, but with one choke per cylinder (i.e. 4 individual carbs or twin DCOEs) it's difficult to get a suitable vacuum signal, so the vacuum advance is very often left disconnected.
Ideally you need ditch the clockwork ignition and have a mapped system fitted with a throttle position sensor for engine load, and set up on a rolling road to give you the best power and economy. If you have to stay with the distributor it's a case of "suck it and see". You can try connecting the vacuum signal from each carb to a small plenum in order to smooth out the pulses and get a usable vacuum signal, but unless the advance curve has been modified to suit the engine you will just have to play with static advance to get it running as best you can without pinking under load.
Ideally you need ditch the clockwork ignition and have a mapped system fitted with a throttle position sensor for engine load, and set up on a rolling road to give you the best power and economy. If you have to stay with the distributor it's a case of "suck it and see". You can try connecting the vacuum signal from each carb to a small plenum in order to smooth out the pulses and get a usable vacuum signal, but unless the advance curve has been modified to suit the engine you will just have to play with static advance to get it running as best you can without pinking under load.
Thanks for that - sort of what I had arrived at myself via trial and error. I will re-set the timing to be as far advanced as possible with out pinking.
I was thinking about getting a mappable ECU later this year - so this should sort it out for me.
How would I recognise "pinking" is it audible or will I notice it in another way?
Cheers
I was thinking about getting a mappable ECU later this year - so this should sort it out for me.
How would I recognise "pinking" is it audible or will I notice it in another way?
Cheers
3rd gear 2-3000 RPM and put the engine under load on a hill. If it's pinking you will hear a tinkling/rattling type sound from the engine. Once you have this back the dissey off 5mm and try again till it sounds right.
The way "modern" systems work is with a knock sensor, when this detects pinking it backs off the timing a bit so no damage occurs.
The way "modern" systems work is with a knock sensor, when this detects pinking it backs off the timing a bit so no damage occurs.
Put the timing back to where it was if it was running ok with no pinking noises.
Then read this before you play with it further.
http://www.pumaracing.co.uk/PINTO.htm
Then read this before you play with it further.
http://www.pumaracing.co.uk/PINTO.htm
Hi there Pumaracing - I did drop you an e-mail yesterday, before you posted your comment - thanks. I have read and try to absorb your information - very comprehensive.
As I said in my e-mail, are you back into doing headwork or are you still on sabbatical ? I would like to go down the porting / larger valve route. I would like to acheive 150 / 160 BHP with the Pinto. Any more and I will change the whole lump I think. I did speak to a race engine builder yesterday who claimed to have got 240BHP out of a Pinto...
Many thanks
As I said in my e-mail, are you back into doing headwork or are you still on sabbatical ? I would like to go down the porting / larger valve route. I would like to acheive 150 / 160 BHP with the Pinto. Any more and I will change the whole lump I think. I did speak to a race engine builder yesterday who claimed to have got 240BHP out of a Pinto...
Many thanks
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