Trouble shooting 123 dizzy

Technical advice Q&A

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rswaffie
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#21 Re: Trouble shooting 123 dizzy

Post by rswaffie » Fri Jan 11, 2019 8:54 pm

Cheers Tom.
I’m going to do a complete check of the ignition and charging circuits before I put the dizzy back as I can’t help thinking that some of the recent electrical issues I’ve had seem to have occurred since connecting the dynator through the relay to the ignition light.
Richard

S1 3.8 FHC Opalescent Golden Sand with Tan Trim 889504
Nearing completion of a comprehensive nut ‘n’ bolt restoration in my small, but utilitarian garage :wrench: :hammer: :fingerscrossed:

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JagWaugh
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#22 Re: Trouble shooting 123 dizzy

Post by JagWaugh » Sat Jan 12, 2019 7:57 am

Tom W wrote:
Fri Jan 11, 2019 8:21 pm
My 123 wasn’t good to 20v. At about 15v, it causes the ignition to cut out, thought it doesn’t seem to have caused any permanent damage. I had a faulty relay in the alternator circuit, this caused the regulator to see a lower voltage than the alternator was putting out, and concequently the car got overcharged.
As I understand it they have built it to handle up to 20(ish)V without permanent damage. What happens when the voltage goes too high is that the CPU does a reset, and can miss a spark for the brief period that restart takes.

I had a problem with a TR3A to which we'd fitted a 123/tune to. It ran flawlessly while standing still and revving through rpms (We put an ignition scope on it and it was perfect), but as soon as you took it out on the road it would cough just briefly about every 8-10 minutes.

Once we jury rigged a separate battery to run just the ignition the cough went away. Then I read somewhere that the 123 will reboot under overvoltage conditions.

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rswaffie
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#23 Re: Trouble shooting 123 dizzy

Post by rswaffie » Sun Jun 02, 2019 3:15 pm

It’s been a while since the original post, and things have moved on a bit.

I’ve had the 123 6-r-v pos repaired (not cheap).
I’ve fitted the engine earth strap.
I’ve manually set the timing to tdc on no.6 cylinder. I had to do this using a steel rod down the spark plug bore and hand turning the engine until the rod reached max height. I can’t get under the car to see the timing marks on the damper and I think they may have been painted over anyway.
I’ve worked through the 123 instructions:
Located the unit into the engine, drive dog engaged. Rotor points to no. 6 lead position at this stage.
Connected red & blue wires as per +ve earth diagram.
Left the black wire disconnected.
Turned on ignition and turned the body until green led noted. :bigrin:
That’s further than I got last time.
Switched off ignition.
Tightened clamp, fitted cap, attached ht leads in firing order from manual (making sure no.6 at rotor position).
Attached black wire as per 123 diagram.

Time to fire up.
Choke set to cold. Ignition on, whirring from fuel pump and fuel leaving filter and reaching carbs.
Hit the starter button, starter motor kicks in healthily. Let it turn over for 7 seconds. No firing.
Try again for 7 seconds. No firing.
And again. No firing.
Attached spark plug testers to 4 of the six plugs and turned it over again. All four lighting up so power getting to plugs.
Tried several more times, but still no fire up.
Battery is fully charged & plugs clean. Gaps good.

Any suggestions at all?

The only thing that I can think of is that the tdc position I timed it at was not on the compression stroke - is that a likely cause?
Richard

S1 3.8 FHC Opalescent Golden Sand with Tan Trim 889504
Nearing completion of a comprehensive nut ‘n’ bolt restoration in my small, but utilitarian garage :wrench: :hammer: :fingerscrossed:

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andrewh
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#24 Re: Trouble shooting 123 dizzy

Post by andrewh » Sun Jun 02, 2019 3:40 pm

the engine fires not at TDC but at 10 degrees before from memory. That could easily be enough to stop it firing.

Edit and of course you could be 180 degrees out on your TDC anyway without reference to the timing marks or camshafts
1962 3.8 Series One FHC

http://etype860897.blogspot.com/

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Turnip
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#25 Re: Trouble shooting 123 dizzy

Post by Turnip » Sun Jun 02, 2019 3:56 pm

I think the ignition fires on both strokes, so it shouldn't matter which stroke you set it on.
- Edit, forget that, I was thinking of my motorcycle's ignition.
The on-line manual for the 123 -R-V-Pos says it should be set up initially on the timing mark, rather than tdc ("verify that the static timing-marks of your engine align"),so maybe you're a few degrees out?
Try turning the unit clockwise a few degrees to see if you get some sign of life. If the engine starts and then chugs a bit, try rotating it a bit more. At least then you'd know if it's working or not.

Simon
Last edited by Turnip on Sun Jun 02, 2019 4:06 pm, edited 1 time in total.
1965 Series 1 4.2 FHC

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#26 Re: Trouble shooting 123 dizzy

Post by mgcjag » Sun Jun 02, 2019 3:59 pm

Hi Richard......you found tdc with the steel rod but was that on its compression stroke......which it needs to be..and not the exhaust stroke.....hence the 180deg that Andrew mentions...Steve
Steve
1969 S2 2+2 & Building a C type replica

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#27 Re: Trouble shooting 123 dizzy

Post by rswaffie » Sun Jun 02, 2019 4:16 pm

Andrew, Simon, Steve

Thanks for the responses. For clarity, as there appears to be differing opinions, does the plug fire only on the compression stroke? If so, then that will be the first thing I’ll look at.
Richard

S1 3.8 FHC Opalescent Golden Sand with Tan Trim 889504
Nearing completion of a comprehensive nut ‘n’ bolt restoration in my small, but utilitarian garage :wrench: :hammer: :fingerscrossed:

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Turnip
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#28 Re: Trouble shooting 123 dizzy

Post by Turnip » Sun Jun 02, 2019 4:23 pm

Yes.
With the plugs out, put a wine cork over the 1 & 6 spark plug holes. When a cylinder is on the compression stroke the cork will fall over.
1965 Series 1 4.2 FHC

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andrewh
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#29 Re: Trouble shooting 123 dizzy

Post by andrewh » Sun Jun 02, 2019 4:32 pm

you WILL be 170 degrees out if there is no puffs or bangs at all imho. ( 180 minus the 10 degree BTDC )
1962 3.8 Series One FHC

http://etype860897.blogspot.com/

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#30 Re: Trouble shooting 123 dizzy

Post by rswaffie » Sun Jun 02, 2019 4:38 pm

Thanks all - it’s now clear in my mind and I’ll have another crack at it tomorrow.
Richard

S1 3.8 FHC Opalescent Golden Sand with Tan Trim 889504
Nearing completion of a comprehensive nut ‘n’ bolt restoration in my small, but utilitarian garage :wrench: :hammer: :fingerscrossed:

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PeterCrespin
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#31 Re: Trouble shooting 123 dizzy

Post by PeterCrespin » Mon Jun 03, 2019 5:45 am

360 degrees out (two strokes) not 180 (one stroke, i.e. BDC). Believe nothing, verify everything, starting with the right stroke and timing marks.
1E75339 UberLynx D-Type; 1R27190 70 FHC; 1E78478; 97 XJ6L

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#32 Re: Trouble shooting 123 dizzy

Post by andrewh » Mon Jun 03, 2019 6:18 am

Thank you Peter. It was hot yesterday.. damn hot! Of course 360 not 180 duh Anyway. Use the timing marks that’s what they are for and check the rotor is pointing to number 6 when at 10 btdc.
1962 3.8 Series One FHC

http://etype860897.blogspot.com/

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#33 Re: Trouble shooting 123 dizzy

Post by PeterCrespin » Tue Jun 04, 2019 8:47 am

andrewh wrote:
Mon Jun 03, 2019 6:18 am
.... Anyway. Use the timing marks that’s what they are for and check the rotor is pointing to number 6 when at 10 btdc.
Sort of, but my own attitude is different. I don’t believe timing marks and have never cared where the rotor points....

If troubleshooting (as per thread title) the timing marks are suspect and not to be used until verified. There are plenty of ways they could be miles out ( e.g.120 degrees if someone fitted an XJ damper) or out just enough to mislead more subtly (e.g. slipping damper outer ring). If something’s not right then the timing marks are one of severaI prime suspect not a reliable witness, until corroborated. I only truly trust timing marks if I am finishing off an engine rebuild and have checked TDC before putting the head on. I then secure their future usability by a dab of paint across the rubber sandwich.

The rest of the time, I do a quick and dirty check with a screwdriver down the plughole every time I use them as part of any static timing check (after having a finger over said hole to check it’s the compression stroke. Even coming from a Belgian family, I find I have my fingers available more often than two fresh wine bottle corks like Turnip #28, lol.

The rotor can point anywhere it wants, depending how knowledgeably the distributor drive was assembled. The only troubleshooting diagnostic is that the correct anticlockwise firing order follows the timed cylinder 1 or 6, which could be any terminal on the cap, if necessary.
1E75339 UberLynx D-Type; 1R27190 70 FHC; 1E78478; 97 XJ6L

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#34 Re: Trouble shooting 123 dizzy

Post by rswaffie » Tue Jun 04, 2019 12:44 pm

Hi All,
Having considered all the hints & tips, and having had a chat with Steve, I had another crack at it this morning.

I charged the battery overnight, cleaned and checked all the plug gaps and found the timing mark on the damper and marked it with white paint pen.

To ensure I was timing on the compression stroke this time, I popped a rubber bung into 1 & 6 and turned the engine until they popped out. Using my mobile in photo mode under the sump so I could see the mark from above, I continued to turn until the pointer & mark roughly aligned.

Image

I then ran through the 123 setup once again. Turned the unit until the green light just lit up, checked the rotor was pointing to no.6, connected the black wire and fitted the cap.
Tightened up the pinch bolt.

Choke set to cold, ignition on, fuel pump whirring.
Hit the button and it coughed and spluttered into life at the second attempt !

It will need to be fine tuned next, but happy with that.

Thanks to all for the advice.
Richard

S1 3.8 FHC Opalescent Golden Sand with Tan Trim 889504
Nearing completion of a comprehensive nut ‘n’ bolt restoration in my small, but utilitarian garage :wrench: :hammer: :fingerscrossed:

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#35 Re: Trouble shooting 123 dizzy

Post by andrewh » Tue Jun 04, 2019 1:42 pm

Excellent news. Glad she has stared up ok.
1962 3.8 Series One FHC

http://etype860897.blogspot.com/

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#36 Re: Trouble shooting 123 dizzy

Post by 288gto » Tue Jun 04, 2019 11:13 pm

:bouncyyellow: :dance: :bouncyyellow:
Simon
1969 S2 OTS

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