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Ignition advance, possible damper pulley slippage?

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In preparation for the arrival of a 123Ignition Tune+ i decided to take ignition advance readings from my car as a starting point.


I got readings using a Gunsons Advanced timing light of :


Tickover, about 800 revs, 16 btdc

1000 17

1500 18

2000 22

2500 26

3000 28

3500 30

4000 36


I then backed the ignition off to 12 btdc and the idle slowed and was rougher, engine much happier at 16, and no pinking under load at any revs.


This doesnt seem quite right, as even though my engine is modified, i dont have full details but +60 forged pistons and possibly a 777 cam ( 145 bhp at the wheels at enginuity) 16 degrees at idle seems too advanced.




1, crank damper pulley has slipped, do they really do this and if so by only 4 degrees??

2, timing light incorrect, but i doubt its wrong in the basic mode with no advance dialled in?


I guess i need to measure tdc, but from what i read on the forum it wont be easy to get an accurate reading?


Thoughts please!


I plan to setup the 123 with the same curve as the existing dist to get started, then probably a proper rolling road tune to get the best out of it :-)



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I was just looking at such tools Peter!


I have no idea whether tdc on the damper is actual tdc, i guess now is a good time to find out :-)



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Hi Neil


I’ve not had a rr setup just a power run.

So i dont have evidence as to the state of the damper.


My car is a total mongrel, especially the engine !

So it jas a cr damper with a white line at 4btdc, but also a mark at 12btdc in white from the rebuild.


As above it doesnt run great at 12btdc.


I clearly need to confirm tdc, will buy some sort of tool.


I’d just need a 14mm tdc stop, and then mark either side of tdc and halve the difference for tdc?

or would a 14mm stop with a built in gauge be better??


Keen to get the car setup as best it can be ....... redy for trackdays and general use :-)



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Lumenition optronic at the moment Neil, so no points.


Runs great but i like the idea of the 123tune+, for bluetooth tuning and immobilisation.


I’ll buy a piston stop and check tdc, then set 123 to current adcance curve as a start.


Happy New Year you you too.



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Actually, scratch the buy a tool option - make a tool instead !


After an hour of fun in the garage we have a special tool





Old sparkplug cored out ( theyre tough little buggers!) tapped and long bolt inserted


The tapping isnt very strong as theyre wasnt much metal but should do the job, will try tomorrow.



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Thanks for the comments Roger and Barry


The serrations are from over enthusiastic clamping in the vice.....

I hadnt thought of the exhaust halve being an issue, will be careful!



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Engine built 20 years ago Neil!


Power run was in 2014 if i recall.


I’m not planning on toching the motor in any serious way until it demands attention, ie something goes wrong!


Swapping out for new ignition with the same advance curve is all i’m doing right now.


Although you make a good ‘it aint broke so dont fix it’ point !



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Keep the old dizzy in the boot ;)


Fitted with points and a condenser, exactly what i plan to do Neil


Tom, ingenious !

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So.... using the improvised tdc tool i am able to determine that the tdc mark is 8-9 degrees out.


Thats interesting as when i set the timing to an indicated 10btdc that idle was slow and rough, i then set it ‘by ear’ to the least advance that gave the best idle and that was 16btdc apparent.


With the 8degree error this equates to an actual 8btdc


This morning i reset to 18apparent which is 9-10btdc true, car idling and running great and no pinking.


So a useful test!


I determined that the damper has slipped and by 8-9degrees.

I guess it will slip again sometime but as long as i set the ignition to the correct tdc, that doesnt really matter.


Am pleased as if i had installed the 123 ignition and timed to ‘10btdc’ on the pulley the results would have been rough running and uncertainty. The 123 is due in the -ost this week so look out for that thread ...... :-)


Think i’ve earned a coffee and possibly cake !


Happy New Year everyone !



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If the damper has 'slipped' that much it implies the elastomer bond has sheared. What is to stop it becoming completely detached, perhaps at high revs ?

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If the damper has 'slipped' that much it implies the elastomer bond has sheared. What is to stop it becoming completely detached, perhaps at high revs ?

That is a good point Rob


I’ll check out replacement / refurb options but i think they ate limited?



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Nice day here so fitted the 123tune+ that arrived in the week.


What a nice easy job!


The distributor fits beautifully, only issue was a slightly fat o ring that i swapped out for a thinner one.


Did a basic setup and the car fired right up.


Have also installed the recommended Beru coil, which is a nice shade of red.


The app for monitoring the engine via bluetooth is nice, a little slow in responding but ok

I set the map as before to begin with, and a rev limit of 6000......and also set the built in immobiliser.


Took the opportunity to tidy some wiring, the lumenition was wired direct to the ignition switch so ive reinstated the ignition feed to be via a dedicated fuse.


Dont think i can hear or feel any difference from the new setup, as expected with the same timing.


Next ill buy a new damper and mark it for tru tdc.


Then its a rolling road to tune the ignition properly and see what difference that makes.


All in all a fun couple of hours tinkering



Ps, yesterday at about 7pm i asked Leeapk , the shop i bought from, a question about the coil to which they replied within an hour!, so thats a recommendation for leenapk.nl !

Edited by SDerbyshire
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