Sq4 MkI- new life

[Gui.dorey]

I think I may have found the culprit (2nd photo). The metal disc came loose from the lead and was just loose in the distributor cap. What do you think?

Nev, I don’t have any suppression leads - see 1st photograph.

[simon.holyfield]

Could be, especially if the lead was pulling out of the cap. The strands should be splayed out of the washer.

[daveleek]

Gui,with the Thorspark ignition maybe you need resister plug caps,what do they recommend in the fitting instructions

[Gui.dorey]

Good news! The fault was indeed the HT lead which had pulled out of the washer in the distributor cap. Today she ran without problems. Thank you Paul for pointing me in the right direction.

I just did a short ride of about 20 kms, and all went well. Kept top speed below 70 km/h and just cruised along. Still needs some fine tuning for the ignition timing and air needle on the carb, but that’s fine. The oil pressure gauge kept around 20-30 psi, once at temperature, on top gear and cruising along, so it seems all right for now. However the needle does drop to O when I stop at an intersection and running at idle… don’t like that much.

Cheers,
Gui

[paul.jameson]

I am pleased to hear it is now working ok. You don't have any ideas as to why my 1937 Square Four intermittently runs perfectly but then develops a serious misfire do you?

As I have said so often about Square Fours, it doesn't matter what the problem is, but the symptom is a misfire.

Going through France once, the Square started to misfire, so I stopped. Sure enough, John Bradshaw, who was with me, spotted that my rear tyre was going flat ! ( For the record, I had a sticking exhaust valve and a slow puncture, but the misfire was the first I knew of either.)

[Gui.dorey]

You don't have any ideas as to why my 1937 Square Four intermittently runs perfectly but then develops a serious misfire do you?

I would guess something to do with the ignition

Interesting enough, it didn’t occur to me to look at the ignition first, because she started and settled into idle perfectly, and ran well on the stand with no misfires at all. The misfires only came later. The most obvious symptoms after taking off was a lack of power and that the engine didn’t rev up once in gear. Thought it might be the timing but as advancing and retarding the distributor didn’t change anything, I started looking at the Solex with a displeased suspicion. Poor Solex, getting blamed for nothing.

[nevhunter]

Sticking exhaust valves are not that uncommon. Some of the anti friction additives can cause it particularly IF you are motoring a bit faster than usual, and moreso with IRON Heads which run hotter that alloy ones. Nev