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Correct Ignition Timing Help


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#1 tamlamotown123

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Posted 09 June 2018 - 06:56 PM

Hi I have trouble setting the engine to start and run smoothly for some time. Engine is a 1293 Cooper S.
By pure chance a previous owner who owned the car from 1980 to 86 contacted me having spotted it at the local garage awaiting an MOT.
He told me he fitted a 649 Camshaft and a big valve head.

So can anyone advise the correct timing is for this?, The carbs have new M needles at the moment and LCB exhaust.

Any advise appreciated

#2 Thelowrider

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Posted 10 June 2018 - 12:32 AM

I set them up at 10deg as rule of thumb then adjust by ear

#3 Moke Spider

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Posted 10 June 2018 - 03:38 AM

That's a pretty wild combination for the street, to the point where personally, I wouldn't put up with it, but, that, just my take on it. The Factory 649 was referred to as a 'Full Race' Cam, with circa 300 degree duration and it wouldn't come on until around 4000 RPM.

 

As far as timing goes, crank the engine up to around 4200 RPM and then set the timing to around 28 - 32 degrees.



#4 Bat

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Posted 10 June 2018 - 06:51 AM

Hi,
With a full race cam in it you're not going to get it to run smoothly probably until 2000 rpm.

If you want to stick with that cam I'd recommend fitting a mappable  ignition system.
I did on a 1380 with a 285 cam and it made a massive difference, I had as much torque at 1500 rpm as a standard mini had in total.
All the power and drivabilty you lose with a bigger cam you can dial back in with extra advance.
Idle speed was fairly smooth at 1000 rpm as the ECU automatically alters the timing to suit.
It's stuff you just can't do with a distributor based system...
Cheers  :proud:


Edited by Bat, 10 June 2018 - 06:55 AM.


#5 tamlamotown123

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Posted 11 June 2018 - 07:04 AM

Thanks for your comments and advice, if I knew about the cam I would have changed it when the engine was on the bench.Thats what I intend to do when I have the appetite to strip it down again, kind regards to all

#6 Pigeonto

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Posted 11 June 2018 - 07:32 AM

Hi,
With a full race cam in it you're not going to get it to run smoothly probably until 2000 rpm.

If you want to stick with that cam I'd recommend fitting a mappable  ignition system.
I did on a 1380 with a 285 cam and it made a massive difference, I had as much torque at 1500 rpm as a standard mini had in total.
All the power and drivabilty you lose with a bigger cam you can dial back in with extra advance.
Idle speed was fairly smooth at 1000 rpm as the ECU automatically alters the timing to suit.
It's stuff you just can't do with a distributor based system...
Cheers  :proud:

Absolutely right. I've set 40 deg advance @1000 in the past and the idle is not bad at all. However come MOT time ( if you need one) remember to put it back or HCs will be off the scale.   And open up the idle stop screw quite a way to counteract the poor idle . Why HC issue I've never known when it's running better at that amount of advance  suggesting a better burn  :shy:



#7 nicklouse

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Posted 11 June 2018 - 07:56 AM

 

Absolutely right. I've set 40 deg advance @1000 in the past and the idle is not bad at all.

 

the last time heard of someone setting the timing to 40 degrees they had no idea what they were doing.

 

they set it to 40 degrees at 1.5k when it should have been 14 degrees at 1.5k. it went an made lots of noise but that was it.

 

no way a A series needs that much advance so low in the revs. see above.



#8 Swift_General

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Posted 11 June 2018 - 08:50 AM

40 degrees advance at 1000?! No A series should need that much advance, let alone at little more than tick over, for the centrifugal advance to provide even more higher up the rev range.

#9 Pigeonto

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Posted 11 June 2018 - 10:02 AM

Ever tried it ? I'm just agreeing with Bat. He didn't quote figures but I'm too long in the tooth to worry. and if it gets the guy the idle he wants...... This is with programmable ignition only; and IDLE advance. NOT POSSIBLE WITH A DIZZY

Need to know exactly what you're doing. Drops back to normal timing once going past 1200 or so and has to be set properly on load where pinking can occurr.  Just like you would when writing any advance map. It's only for  idle as Bat said. 

When using a cam with a fair degree of overlap the  fuel/air mix at idle is contaminated with exhaust gas, coupled with extremely poor cylinder filling, those conditions require much much more advance to get  decent running.

It's not for the faint hearted and you need to know how to set things up, cranking advance is fully controllable too with an ecu so can be set perfectly.

This is a discussion forum and people read, consider, ask, then make their own decisions. If no one puts their findings down then info can't be shared.

Regards



#10 Bat

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Posted 11 June 2018 - 10:41 AM

Hi,

Don't knock it until you've tried it!

With the massive amount of overlap when you're off cam there's pratically no compression. I had rimflow valves too.

See the dyno for the figures, it was geared 20mph per 1000rpm so the 30 mph figure is 1500 rpm.

It had a Weber 45 and it pulled like a train from idle and 35 MPG @ 70 MPH cruising.

Uploaded an ignition map for you to see too.

 

Dyno operator stopped at 100mph as he thought I was taking the p**s with a dodgy rev counter as it only read 5000 RPM when putting out 109 BHP.

If you read and research and look at my map you'll see that once you're past peak torque you can start to add advance again, this is why the torque curve is so flat.

Please make sure you know what you're talking about before rubbishing two peoples actual experience, thanks :proud:

 

Cheers,

Gavin :proud:

 

Attached Files



#11 Bat

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Posted 11 June 2018 - 10:55 AM

Hi,

My engine was built from 2 different ones to basically the same spec as the one on the back of Vizards original blue book.

I mapped the mini by driving around using the latest gadget at the time, a car PC.

I had it on the dyno to check I was doing it right and get the jetting sorted on the Weber.

We were both plesantly surprised I think it's safe to say. :D

Cheers,

Gavin :proud:

 

EDIT: I took it a stage further than Pigeonto and kept the advance going up rather than dropping back after 1200.

Idle parameters for the ECU to add or subtract advance from the map figure to stabilise the idle at 1000rpm were +12 or -5.


Edited by Bat, 11 June 2018 - 11:02 AM.


#12 Pigeonto

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Posted 11 June 2018 - 11:10 AM

It's under constant review and subject to change without notice lol !!

I've just been cautious. Now my Rolling road is up and running though I have much playing to do, have noted what Bat has put and will be using/adapting it. This is, after all, a discussion forum   :D

 EDIT, I should add that  it does indeed go on up after 1200, to above 40deg, on light load,  good for fuel economy too.   


Edited by Pigeonto, 11 June 2018 - 11:18 AM.


#13 Bat

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Posted 11 June 2018 - 11:13 AM

It's under constant review and subject to change without notice lol !!

I've just been cautious. Now my Rolling road is up and running though I have much playing to do, have noted what you have put and will be using/adapting it. This is, after all, a discussion forum  :D

Hi,

That was map 14 out of 17 that I messed about with and I didn't save it each and everytime.

When chucking buckets of advance at it an air temp sensor is crucial!

I had a cold air feed from the fresh air vent across the back of the dash to the weber box ;D

Cheers :proud:


Edited by Bat, 11 June 2018 - 11:16 AM.





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