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A very strange question about testing ignition timing


Unclejake

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Shanks were good! Had potatoes too :shock:

Your suggestion makes sense. Let me get a photo to be certain we are talking about the same thing but at this stage I think increasing the air gap would require cutting the steel posts that 'activate' the trigger/reluctor.

I am grateful for the advice. I will get a photo tomorrow and post it on Wednesday.

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cant cut the posts

but you could reshape the ramp... the ramps just conditioning anyways IMO

keen on pics :D

glad i can help

anythign good to eat tonight ?

we had hotdog's and chips...yum

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You realise that with your setup the HT will never exceed 2 to 3 Kv. With that there's a possibility that your timing light might not be triggering properly.

In a "real" motor the HT will go up to maybe 25Kv under load.

I'd be doing a comparison with a "stock " cortina dizzy.

Steve

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i see whats forced is sayng

becauae the real motor has compression there is more resistance in the spark gap so in real world it will load up more and make more voltage to arc across the airgap

could be simulated by just increasing teh spark gap or putting a large ballist on the earthing plate

though this would show as a inconsistant spark or a weak spark ......it shoudlnt change the timming

its a reluctor setup so the trigger isnt dependant on the coil/points at all

if your static timming was 0

advanceing would be BTDC

retarding woudl be ATDC

hope this helps

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The signal to the timing light seems fine except at very low RPMs (on the test rig). Now that I have the rotor phasing right the signal is steady - even at 8,000 RPM

The issue is this retard at medium revs.

Photos will be taken tonight and we can look at widening the air gap to possibly solve the problem.

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i see whats forced is sayng

becauae the real motor has compression there is more resistance in the spark gap so in real world it will load up more and make more voltage to arc across the airgap

could be simulated by just increasing teh spark gap or putting a large ballist on the earthing plate

though this would show as a inconsistant spark or a weak spark ......it shoudlnt change the timming

its a reluctor setup so the trigger isnt dependant on the coil/points at all

if your static timming was 0

advanceing would be BTDC

retarding woudl be ATDC

hope this helps

tis true - one thing I learned from Sefton was you may get a decent spark out of a plug at 1 atmosphere but with compression

it may misfire.. not too sure how or if it will affect the timing because the signal should be the same but it will definetly affect the actual spark intensity at the plug electrode..

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The magnetic pickup (hall effect) has a slight fixed delay to it. The rise time in the coil also causes a slight fixed delay. The higher the voltage before current flows, the more delay.

So at low rpms, only a small fraction of a degree.

Higher rpms, more degrees

more voltage, more degrees.

As for coming right at the top end, I'll pass on that, too hard.

Steve

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Here is a photo.

This is the EXACT moment the spark appears. Don't forget the distributor runs anti clockwise and I have phased the rotor timing within a degree or two of perfect by observing the rotor with a timing light and a hole in the dizzy cap.

My problem is several degrees of retard as the dizzy spins faster

Look at the reluctor (or trigger??) - reckon I need a balast resistor???

dsc01025cw4.jpg

By unclejake, shot with DSC-R1 at 2008-08-

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you supply power to the dizzy at all ?

just makign sure

subaru is a vr setup

I don't know what 'vr' is sorry.

I have been supplying power to the dizzy as per the way I wired the race car. That wiring system is replicated on the test rig without the MSD gear. You can't really get it wrong with those dizzys as the don't sparj at all if the polarity is wrong. The dizzy is ex. Subaru Leone

The spark looks great. It is just the rising retard that shits me :?

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