SQ4 Mk2 starting issues

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berniejones
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Re: SQ4 Mk2 starting issues

Postby berniejones » Fri Apr 24, 2020 7:02 pm

Thanks both - Powerspark sounds good. I like that plastic film - clever stuff, will likely order some - £2.45 for a small piece seems good.
I'm going to take some pics of my timing marks and post to see if others think this is a decent way of strobe timing. Seemed a simple solution to me although perhaps limited in accuracy by the available diameter of rotor and stator parts. Would be good to know what folks think.

Regards,
Bernie
'56 SQ4
'52 BSA M21
'56 BSA M21 combination
'61 Dommie 99
'64 B40 SS90
'65 A50CC project
AOMCC# 4631

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Re: SQ4 Mk2 starting issues

Postby Paul_Linden » Fri Apr 24, 2020 8:54 pm

I’m interested to hear about timing with a strobe light.
I’ve sent you a PM about the magnetic plastic.
Ariel Square 4 mk2, Ariel Square 4 mk3 (yes, really), Ariel Colt, Matchless G12, BSA C12. Room for one more......

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Re: SQ4 Mk2 starting issues

Postby paul.jameson » Fri Apr 24, 2020 9:02 pm

I also timed on No3. The static point of firing was when the rotor arm centre line was in line with the centre of the rubber grommet through which the two wires exit the distributor base plate. I advanced from that by Guess and by God with a bit of experience thrown in but I am not far out. To date, the Healey has always started first kick, which is what I expect from a Mk II with SU carb and electronic ignition.

I may suffer in future for that, no doubt!

My post about Steve Carter being an inspiration a day or two ago was a reference to the thought of fitting a timing disc onto the rear crankshaft using 2 (singles) nuts, using a pointer for TDC and then strobing the timing, obviously with the primary case off. Given that once you have the timing right you scribe a mark between distributor and housing so that you can set it again if need be, this might be an easy way forward.
Paul Jameson
36 4G, 37 VH, 54 KH(A), 75 Healey 1000/4, 52/53 ex ISDT KHA (project).
Former Machine Registrar & Archivist, General Secretary and Single Spares Organiser (over a 25 year period).
Now Archivist once more - but not Machine Registrar.

Gui.dorey
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Re: SQ4 Mk2 starting issues

Postby Gui.dorey » Fri Apr 24, 2020 9:10 pm

Bernie, I used a strobe to time mine. It was messy but not too difficult. Mine’s a MKI, but should work just the same with a MKII.

I took off the inspection plug on the front crank shaft. Then made a mark on the Nut and the case (Edge of the inspection plug hole) with a marker pen - Edding or similar. One mark for TDC on Nr 1 and one mark for the given degrees BTDC. Oh and a mark for full advance BTDC. Then ran the engine, pointed the strobe at the front crank nut and case and adjusted the distributor as needed. Did this both at idle and at a higher RPM to check advance. Quite a bit of oil is spewed out as the inspection plug is not there, so a bit of a mess all over the workshop, but in the end easy to do really. Took me longer cleaning up than the timing itself.

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Re: SQ4 Mk2 starting issues

Postby berniejones » Sat Apr 25, 2020 2:31 pm

Gui - that's exactly what I've done. It's possible to remove the cap without disturbing the front pipe and I've just used typing correction fluid to make white base marks on both the crank bolt and the casing and then ink-marked radial lines for TDC and fully advanced using the standard rod-in-plug'ole technique.

This shows well under the strobe. Mine does jump around a lot though which I'm hoping will be cured when I fit the new components.

But.... I'm now a bit concerned as there's no oil coming out when I do this!!

Cheers,
Bernie
'56 SQ4
'52 BSA M21
'56 BSA M21 combination
'61 Dommie 99
'64 B40 SS90
'65 A50CC project
AOMCC# 4631

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Re: SQ4 Mk2 starting issues

Postby D.Ryan » Sun Apr 26, 2020 7:22 am

Electronic ignition (EI) strobe timing.
Hi, Dennis is my name and I am in Melbourne Australia. I have a 1950 MkI rigid square four that is really all 1949 except for the fork bridge, headlight and of course speedo location. The oil pump and distributor indicate 1950 so that is what I think the issue date is.
Having said all that I have now recently gone over to 12 volts and looked for an alternative EI to replace the home made 6 volt EI that was in place. I settled on an Accuspark kit no 39 (negative earth) for two reasons. Cost and not too much modifying. In fact all I had to do was open out the central hole in the plate to clear the advance/retard unit. I also had to drill/tap two 3mm holes to relocate the sensor unit to give distributor adjustment without fouling the oil tank. I relocated the screw holes 5mm anticlockwise from the existing holes. Marking out accurately is important and I also found that the two holes are not on the same PCD. As far as static timing goes I have found that the magnet has passed the centreline of my unit when it triggers so to find out where it fires this is what I have done. The distributor is off the bike.
1/ I arbitrarily placed a thin white line both on the top of the unit and on the magnetic ring. Note: Specify the biggest A/F ring they have for the Lucas line of rings (.700")
2/ with a spare coil, battery and associated connections I set the distributor facing my strobe light. (Always fire the coil through a spark plug to avoid excess current through the sensor unit)
3/ using a battery drill I rotated the distributor at around 100 to 200 RPM. This indicated the line on the ring was out a bit so I adjusted the position of the line to where I thought it should be and re run the test. The line being spot on I re fitted the distributor on the bike and set the timing with a dial gauge at .55 mm (8 degrees) BTDC. This is my preferred static timing with the 15 degree A/R plate.
4/ I do have a sealed degree plate I made that fits on the front crank and is driven by the slot in the crank nut. When I run the bike no oil leaks and the timing proved to be spot on. It is interesting that 38 degrees before BTDC seems to be the go to advanced timing.
Apologies for the long winded first post.
Dennis.

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Re: SQ4 Mk2 starting issues

Postby berniejones » Sun Apr 26, 2020 10:03 am

Hi Dennis,

Very interesting to read about another option for switching our 4's to EI ! I think that your method of determining the firing point would also work for other brands of units to set the initial point for static timing which would be very useful.

Am I right in thinking that the 15 degree A/R is measured in terms of camshaft angle? If so that would make sense as the crank angle would then be 30 so combined with the static advance set at the crank thatwould give 38.

I still haven't ordered a kit yet - usually I would take less time but with this lockdown still in place things seem very different. Am I the only one that has slowed down so much? It's almost as if I don't really want to hurry to finish a particular task as then I'll need to think of something else to occupy my time (before my wife spots that I'm looking idle!!).

Cheers,
Bernie
'56 SQ4
'52 BSA M21
'56 BSA M21 combination
'61 Dommie 99
'64 B40 SS90
'65 A50CC project
AOMCC# 4631

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Re: SQ4 Mk2 starting issues

Postby D.Ryan » Sun Apr 26, 2020 10:50 am

Hi Bernie,
The advance plate in my distributor is marked 15 degrees at the distributor and that does translate to 30 degrees at the crank.
The Accuspark unit is a shaped Bakelite and metal plate that fits straight on to the DKX4A distributor. As to the longevity of the unit I have no idea but time will tell. It would be an easy fix to fit a replacement unit of any make utilising the Accuspark magnet ring in case of a failure. Incidentally the same distributor casting is used on BSA c10 an c11 motors albeit without the 4 cylinder cam. The do make a good holding jig when machining the bore to clear the A/R unit at the very least. The EI path is the way to go as the wear in my distributor was mostly repairable except the cam itself varied from lobe to lobe by as much as 5 degrees. That is an unacceptable ten degrees in timing from one cylinder to another in my case.
In the past 6 weeks I have made a Bennet Longman alternator lookalike which works flawlessly and fitted the Accuspark. I work full time and fortunately have been on leave for the last five weeks with one week to go, so making hay while the sun shines even in these dark times.
Regards Dennis

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Re: SQ4 Mk2 starting issues

Postby john.bebb » Wed Jun 10, 2020 3:22 pm

Hi Bernie, please beware - ancient carb materials were not designed to be ethanol proof - (ethanol can leech Mazac & other alloys).
Deposition within jets etc will surely occur after a months or so of dormancy.
Some years back the Government deigned to warn us when UK petrol was destined to be lead free; - & most were able to compensate with whatever was necessary... however both Government & petrol suppliers remain remarkably silent wrt the inclusion of bio-ethanol in the petroleum mix (currently now at 5%) but destined to become 10% in 2021... this will exacerbate long term leeching & thus deposition of crud.
Cheers, John


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