Mk1 Sq 4

[Gui.dorey]

On mine as well, just a short bolt as a plug.
However, the rotation range of my distributor is still quite small. It either hits the float bowl or the oil tank. I’ve tried different positions for the flat - back towards the tank, 10 O’clock towards the bowl, and left it at 2 o’clock towards the outside front. I get enough rotation to set the timing but just barely.

I’m also using B6HS plugs. A colder plug should actually avoid pinging (or am I confused now?). Unless what you are hearing is not pinging, but something else. Still, From all I hear from you I still suspect the timing is too advanced, and now that you found out you can rotate your distributor more, it is hopefully solved.

[john.bebb]

"Standard" orientation of distributor body on Mk1 was "Flat" was toward rear - approx parallel to front face of the oil tank.
As a matter of interest - I would like to hear of the methodology used to actually strobe the ignition on a Mk1, thanks. John

[simon.holyfield]

As a matter of interest - I would like to hear of the methodology used to actually strobe the ignition on a Mk1, thanks. John

So would I. Marks/pointer on the engine sprocket I would think.

[Gui.dorey]

"As a matter of interest - I would like to hear of the methodology used to actually strobe the ignition on a Mk1, thanks. John

Hi chaps,

this is how I did it – on a MKI, not sure if it works on other versions of the Sq4. It’s a bit messy, so don’t wear your best clothes and a bit of warm oil spray on your face won’t kill you.

- Unscrew the plug for the front crankshaft.
- Find TDC on Nr. 1
- Mark this position on the front crankshaft nut AND on the edge face of the case where the inspection plug screws on. Use a felt pen, sharpie or confiscate the drawing paints from your yung’uns. I put my marks at 12 0’clock, so one has a straight line from the crankshaft nut to the case.
- Then turn Nr. 1 back to the specified degrees BTDC for the ignition advanced setting. I used a timing wheel for this. Download one from the internet, print it and glue it on a piece of cardboard, make a hole in the centre and screw it on to either the front or rear crankshaft. I believe I used the rear crank for this so I could have the front one free.
- Mark this position BTDC only on the case, not on the nut. Again I used the edge of the inspection plug hole.
- So now you have a mark or line on the front crankshaft nut, and two lines on the edge of the inspection hole on the case. Of the latter, one will be at 12 o’clock (marking TDC) and the other at about 11 o’clock marking the specified degrees BTDC for full advance.
- Connect a strobe light to the Nr.1 HT lead and start the engine (should be previously warmed up). This is when it gets messy. She shall spit gobs of warm oil at you like an angry dragon, but remain stoic and point the strobe light at the front crankshaft nut.
- At idle and if your timing is correct, the lines at 12 o’clock will line up. If not, adjust the distributor head until they line up.
- Then increase your rpms so that the advance kicks in. Now she will be really angry and spew warm oil all over you and your workshop floor, walls and ceiling. You will shake in your boots, but brave the storm and keep your timing light pointed at that front crankshaft.
- At higher rpms you should see the lines line up at your BTDC mark (somewhere around 11 o’clock.
- You can now play with the distributor head back and forth for a fine adjustment – about 12 o’clock at idle, about 11 o’clock at higher rpms, and using your ear to hear how the engine runs better. You will soon find the best setting.
- Shut her off, disconnect the strobe light, replace the inspection plug and get the wash mop out.

Hope I remembered everything....

[Gui.dorey]

Of course I didn't remember everything....

- TDC and BTDC on Nr 1 has to be on the compression stroke, of course.

Simon, Using the front crankshaft inspection hole instead of the engine sprocket is musch easier, because one doesn't have to disassemble half of the drive side, battery tray, etc.

[daveleek]

It should be possible to make a clear plastic inspection cap out of perspex or similar ,or fit a glass window to an inspection cap somehow like modern bike have on there crankcases ,older Harleys had a plug witch was replaced by a clear plastic plug to use a strobe light . I have an old inspection cap witch I will try to make one .

[paul.jameson]

Not wishing to spread confusion but won't the marking before TDC on the front crankshaft be at about 1 o'clock, given that the front crank is geared to the rear one and therefore runs backwards?

[Gui.dorey]

Not wishing to spread confusion but won't the marking before TDC on the front crankshaft be at about 1 o'clock, given that the front crank is geared to the rear one and therefore runs backwards?

You’re right of course! I’m the one whose confused trying to write it down from memory.

To be honest, I’m not sure if it is all worth it. I did it as I was rebuilding the engine anyway. I was curious, wanted to see if I could do it, second guessing myself... But in the end, it was just a good starting point and I finished the fine tuning on the road, finding the best position for the distributor, which in my case was slightly retarded from that starting point. So I suppose one can achieve the same by just finding TDC and points just opening and all that. Today, after all the experience gained with my Sq4, I wouldn’t do it again.

[simon.holyfield]

So would I. Marks/pointer on the engine sprocket I would think.

Did I really write that? Bit of a Homer Simpson moment.

Doh!