Trouble with my timing light

johng

CCCUK Member
Thought I'd check my timing today, but I have a strange problem which hopefully someone can explain for me.
I hooked up my timing light and it was flashing away, but the mark on the torsional damper was nowhere to be seen.
The car starts and runs fine so I thought the timing can't be a million miles off, then I noticed that just occasionally the timing mark showed up and it wasn't far off.
By waiting a while to get the occasional sight of the timing line I managed to set it right and it was very stable, but any idea why it only works so rarely?
I used the light on my boat engine last week and it worked fine.
 

Oneball

CCCUK Member
Have you got an inductive pick up on the light if so number of reasons.

You’ve put it on the wrong way round.

The pick up is too close to another lead

The leads are running very close to each other and you’re getting an induced current in no 1 lead

The 12v source is iffy

You’ve got a very weak spark.
 

johng

CCCUK Member
Thanks guys, it is an inductive pickup. It's not the lead on the wrong way round, I tried reversing the direction and that didn't help. No1 lead is pretty close to No3, I pushed them as far apart as I could, perhaps I should make up a metal shield. I took the 12V from the alternator presumably that should be good enough. I did wonder if No 1 cylinder was only firing occasionally, but the plug looked a nice biscuit colour. If I had a weak spark presumably the light either wouldn't flash, or if it did it should be a the right time shouldn't it?
 

Oneball

CCCUK Member
Even if the spark was weak or intermittent on no1 it’ll still be firing at the correct point.

One more thing to check is that the rotor arm is aligning with the cap pick ups. But difficult without a hole in the cap but if you look at where the electrical wear is on the rotor arm Make sure it’s not right at the edge of the contact.
 

johng

CCCUK Member
Tried several things today that made no difference, better earth, different ht lead and reversed the direction of the pickup again. Had a look in the distributor and the electrical wear marks were slightly off centre. While I was there I cleaned up the contacts, this did make a small difference, the light fired at the correct time a bit more often. I also tried a non inductive timing light. This flashed constantly so I'm pretty sure cylinder 1 is firing, but the light was too dim to see if it was flashing at the right time. On another tack, I can't get the car to idle lower than 750rpm and it's not very stable at that. Is this normal?
 

Oneball

CCCUK Member
The only way I’ve got those non inductive lights to work is in the dark. They’re just not bright enough.

Have you got a plug out while it’s running to see what the spark looks like?

If the throttle butterfly is fully closed I’d look for a vacuum leak somewhere.
 

johng

CCCUK Member
You're right about the old style timing lights, I'd have to put some curtains up in my garage to have any hope of seeing anything!
Haven't tried running with a plug out, but to be honest at the moment I'm happy that the base timing is right and the vacuum advance is working. I'm going to need to borrow or buy a dial back timing light at some point to check what the total timing is, hopefully this will work better than my current light.
The throttle probably isn't fully closed as I have to wind in the throttle stop a bit to keep it running. If I take it down below 750 it dies. I've had it running with the vaccum advance, EGR and cannister purge lines blanked off and it wouldn't run below 750rpm, I'll try blanking off all the vacuum lines tomorrow.
 

Oneball

CCCUK Member
I got the wrong end of the stick thought you meant you couldn’t get the revs below 750.

I wouldn’t worry too much 750 is a nice idle speed. Check the secondary butterflies are fully closed. If they’re sitting open for some reason and you choke the air off on the primaries you loose fuelling too.
 

johng

CCCUK Member
Secondaries are closed, the emissions sticker on my car says the tickover should be 500rpm on the throttle stop and 600 with the air con solenoid on, so I was trying to get close to that. Don't think I've ever actually had a car that ticked over at 500rpm though. 750 would be fine if it was stable, but it's ranging from 600 to 800. Mind you, could just need a good run and clear out. It's been sitting idle for the last 2.5 years, can't really take it for a drive yet though with no interior.
Painter has now delayed the spraying to next month, so I'm imminently going to run out of things to do :(
 

johng

CCCUK Member
So the plot thickens. I tried putting the timing light on number 6 lead as I could get it clear of the other leads and it should be 360 degrees out from number 1. The light worked fine, but the timing mark was 90 degrees out. Tried number 3 lead and the marks lined up perfectly! Looks like the engine is running 90 degrees too far retarded, is this even possible? Checked the static timing and the rotor was pointing at number 2 instead of number 1, so I've moved it round, but my battery went flat before I could get it started. It didn't seem like it wanted to fire though. Is there anything else I'm missing?
 

Roscobbc

Moderator
Are you 100% sure that outer casing of harmonic balancer hasn't 'moved' in relation to where timing tdc should be? It's not unheard of with old balancers. If unsure perhaps check with visualising/using a probe through spark plug hole on no. 1 cylinder to determine tdc?
 

Oneball

CCCUK Member
If it was 90 out on static timing how were you able to pick up the timing mark dynamically when connected to number one?

Have you got the leads in the right order and direction?

Have you got the cylinders numbered correctly?


Other option is you’re timing in number 1 was done off an induced current in the lead.

I’d suggest starting from scratch.

Do as Rosco says. Find TDC on the compression strike for number one and work from there.

I always go for around 5 degrees BTDC for static timing on a fresh engine. Makes it nice an easy to start and it’s not going to be After TDC either.
 
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johng

CCCUK Member
I've been chewing it over whilst eating my dinner and I think you must both be right, the timing mark on the balancer can't be at tdc. I did remove the balancer to replace the timing cover seal and had a good look at it then. As far as I could tell it was still all in one piece. I can't have put it back on in the wrong position can I, as I'm sure it's keyed. It isn't completely loose as now I can see the timing marks they are stable.
I think my light has been working all along and that I just didn't see the timing line because it was so far out of place it was almost out of sight. The occasional time I saw the mark in the right place was probably induced current from cylinder 3.
I'll be seeking out tdc tomorrow! Lucky I've got time to kill whilst I'm waiting for the painter.
 

johng

CCCUK Member
So I found tdc, repositioned the distributor and have set the timing for 6 degrees before tdc. Also adjusted the idle mixture and it idles quite smoothly at 700rpm. Whilst I had the plugs out I also did a compression test which ranged from 145psi to 155psi, which seems fine to me. Think I'll need to get a new harmonic damper though, if the old one has managed to rotate over 90 degrees it can't exactly be properly stuck together. Not sure if I'm going to be able to fit a new one with the radiator in position or not. Last time I removed it there was no rad or body on the car, I had plenty of access then!
 

johng

CCCUK Member
With a screwdriver down the plug hole whilst I turned the crank. Probably not entirely accurate but good enough until I get a new damper.
 

Roscobbc

Moderator
Strangely John I have been having issues myself with setting up timing. The damper on mine is a bit dirty and oily, access is difficult and due that I managed to overlook the correct white 'spot' marked timing mark on the balancer. On my particular engine initial advance should be 21 degree btdc (leaving 15 degrees centrifugal advance in distributor - total = 36 degrees) Using white Tippex I marked what I thought was TDC and initially initially set-up static timing before starting-up. It wouldn't start, kept kicking back and almost seemed like a flat battery.
So (much like John) I went back to basics and found TDC by a process of elimination (and checking visually/physically that 1 no. piston was at TDC. I then checked rotor arm against distributor cap and it was pointing to no. 8 plug lead (rather than no. 1) - confused I visually checked the balancer and realised that mistakenly using the Tippex I had marked the first line I saw (there were two other lines) missing the correct tdc mark with its countdown degree markings. It is now running...........
 
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