Square Four MkI restoration complete - almost....

[pauldridge]

That's great news Gui. I found my own Mk II smoked and leaked like crazy for the first 50-100 miles or so, and seemed to be running hot. Now, with 800 miles on the clock, oil leakage is minimal and the engine seems to be running at a happy, moderate temperature.

Now get out there and log some miles on that beauty!

[allan burgess]

check the compression have you got compression on all cylinders are you using NGK plugs? if so? they soot up very fast a poor starter with sooty plugs allows the petrol to collect on the plug, clean the plugs and try easy start instead of the choke, when mine starts the 4g is first kick and the Mk1 was 2nd kick This became 1st kick when warm . have you converted the MK1 to 12 volt this is a good modification try different plugs If mine does not start I use champion plugs and then check the distributor. Have you got play in the shaft at the top where the rotor is this centre's when it's running but is a pain for starting it effects the points gap Is the condenser OK take it off and connect it across the 6-volt battery charger for a second use an Avo. non-digital and connect across the condenser same polarity the needle should go to 5 or 6 volts and decay to zero use plug caps that do not have a suppressor. Is your petrol fresh? On the carb have you put new nylon bushes on the throttle shaft holding the valve. When you assembled the carb, did you close the throttle valve and then tighten the two brass screws in the shaft the return spring on the throttle cable is it closing the throttle fully and have you set the throttle stop correctly. check that the carbs jets are all as per the manual.

[Simon.Gardiner]

Great work and excellent news Gui.
I see you've got a GB gearbox - I've had one develop leaks from the blanking plugs over the holes in the case for the selector shafts.
I think new plugs are available but as my bike was well in the red for 'time worked' I degreased the area around the plugs on the outside and araldited some thin pieces of aluminium over them (I'd previously checked them before putting the box in the bike and they didn't appear at all loose or corroded, so I figured it was time to be brutal with it....)

SG

[Graeme.crawley]

Timing side bearing Oil hole alignment - continuing note in this thread
I hope this thread is still alive enough to get some feedback, it was the best fit for my question. David Anderson said: further observation is that on dismantling the 4, I have never found the timing side bushes to align with the case oil holes. In one case the owner stated that he had originally aligned the oil holes so it is possible that the bush had spun a little in the case.
Other places advise that they must align so what is really required?
There were 6 timing side bearings in the box of bits for the Mk1. The holes in the bearings are directly opposit each other on all of them. Two fit the crank very well but I am curious about these feed holes. The oil feed to the rear bearing and the exit through to the front bearing are not opposit. Looks like the bearings from Drags have them correctly aligned and for MK2 I understand this migh be important but for MK1 from what David has said, the grove in the bearing will deliver oil to the shaft regardless where the holes are. Am I safe to use these "opposit" type bearings on the Mk1? I currently have aligned one hole with the feed to the front bearing but there seems no logic to this when I think about it, the other hole on the pump side, is closed off by the case so the incoming oil has to get to the grank by following the groove in the bearing. The front bearing hole aligns with the feed hole from the rear and the other opposite hole is blanked off by the case.
Is there any manner by which one can/should pin these bearings on a Mk1? I know they were not originally but my crank case shows some wear even though fitting was tight. Originally I heated the case to about 180 degrees and the bearings would not go in but freezing the bearing and heating the case allowed them to go in easily - rather too easily I thought

[simon.holyfield]

Do your bearings have the grooves around the outside Graeme?

[paul.jameson]

The only pushrod Squares to have the main bearings pinned were the early 4G & 4F (pre 1948?), plus the last Mk IIs (post 1956?). So from 1948 to 1955, the bearings were not pinned. That period probably covers the majority of the remaining Square Fours and although turning bearings are not unknown, they are unusual. So I wouldn't worry about it. I did have the bearing turn on my first Healey which had a 1953 engine. The symptom was the oil pressure warning light coming on whilst ticking over after a long run. The bike got a further 50 miles home with ease and David Jones made me a bigger bearing which cured the problem. The early bush with the groove round the outside is not going to wreck the engine if it turns in the cases, provided you retain some oil pressure. There is a pressure gauge on the 4G and Mk I to monitor this. On the Mk II I think everyone by now is using a Morgo pump which provides such a high volume of oil problems are unlikely. But if the pegged bearing was to rotate on a late MkII without the groove round the outside then disaster would be inevitable.

[Graeme.crawley]

Thanks for the feed back
Hi Simon - Yes the bearing are grooved on the outside which is why I think the alignment question is not an issue. I gather that the Mk2 has the crankcase grooved? I must take a look at my Mk2 case. Wonder why Ariel would change this as I would think it easier to machine the bearing then the crankcase and I must say I do not see that where the holesa re would matter even for a MK2 but might apprecate that when I check mine out.
The bike has the pressure gauge in the tank.
I know the Mk1 1951 in my case was not pinned, just wondering if anyone ever did try to pin them given mine look like they might have turned at some stage although I could not feel any bumps in the cankcase so maybe just oil stains or whatever.
I figured that the oil can get to the front bearing only by going around the bearing groove so no reason it cannot go around to the first hole on the rear bearing. I have a morgo pump.
Thanks again for the quick answers, I will leave them where they are.

[Roger Gwynn]

There are only 2 versions of the timing side bearings 1937-55 with small OD to the flange and the later 1956-58 version with a larger diameter flange that is pegged. The position of the early ones does not matter as the oil will flow around the groove, which is why it is there. As Paul says the bearings were pegged on the iron models using a grub screw into a tapped hole from below the bearing, fitted from outside the case. It is rare for bearings to spin, I suspect usually only when they sieze, bushes are or were available with oversize OD to get round this problem.

[Paul Tarn]

Oil leak - congratulations on getting it started. I have just got a 1939 square four - kicks up second kick but same leak from soldered joint. Was tempted to fix it and have a ride but the apocryphal stories of bikes left standing exploding when run have put paid to that idea.
I’m therefore starting a complete strip and rebuild. Bit nervous about it if I’m honest. I was thinking about just shipping the engine off somewhere but where?
Then spoke to Paul who was encouraging about tackling it myself.
Anyway I have a bike that runs great - will it when I’ve finished !
Well done great start to new year