MkI square four engine rebuild

[Gui.dorey]

Hello there,
I've been restoring a '51 MkI from a basket case, and just about to start reassembling the engine. However, I'm missing a few bits which Draganfly doesn't have on stock, so I'm hopping for some sugestions.

- I'm missing the circlips for the crankshaft ball bearings 1443-37 and the one for the camshaft bearing 1464-37. Is there a modern alternative? Does anyone have the dimensions? Or alternatively what if I just loctite the outer races to tha cases? Bad idea?

- missing bits are the OPR valve body 2151-50 , the stop for the tensioner blade 2110-49, and the 2 anchor pins for the dynamo straps 2358-37. Any help on these would be much appreciated (l'm in Germany).

The head is a mess, I'm afraid. Most of the threads for the 12 studs are gone and some have helicoil inserts. I know the proper fix would be to fill them up and rebore and rethread all of them, but I can't find anyone in my area who can even begin to weld aluminum. So, are helicoil inserts an acceptable fix?

Thanks in advance for any responses!
Cheers
Gui

[simon.holyfield]

All my head studs have helicoils - they are fine. I certainly wouldn't risk welding the head unnecessarily.

[chris.shearwood]

I'm missing the circlips for the crankshaft ball bearings 1443-37 and the one for the camshaft bearing 1464-37. Is there a modern alternative? Does anyone have the dimensions? Or alternatively what if I just loctite the outer races to tha cases? Bad idea?

Hello Gui,

Welcome to the AOMCC Forum!
Although I don't know of a modern equivalent I'll attach a photo showing those circlips. The thickness of them is 0.030"

I think it would be a bad idea to omit them and use Loctitie to secure the outer races. Although Loctite may hold for a while the heat of a Sq4 motor would eventually loosen the races. I would also recommend installing the original lipped type bearings to insure that the outer races cannot move inwards and contact the crankshafts.

Best of luck to you,
Chris

[bob cottam]

Yes, concur with the above- squares run very hot, and as I see it, the chances of a main bearing outer being still tightly held in the case at running temp are pretty much none whatsoever. Them outers will walk! They cannot move inwards much due to the presence of the cranks, and where lipped outers are used, the rollers themselves will prevent inward movement. The circlips are indispensable, as if not fitted, the outers could (probably would) stray outwards towards the coupling gears and that's a considerable distance- the consequences of that could be catastrophic. Loctite will never hold given the heat cycling and relative expansion rates of bearings/ cases .
An alternative circlip may be found at a supplier, as the bearings are a standard item, and will be circlip retained in many other applications. It is quite possible the circlip diameter is easily obtained, but the thickness would be more than 030". If you can obtain a "standard" circlip for those bearings, a machine shop should be able to surface grind the thickness down to fit?? Bob C.

[Gui.dorey]

Many thanks for the quick responses!

To Simon: I'm very relieved to hear about the helicoils. BTW your blog on Amelia is brilliant and I probably look into it once a day

With the circlips, it is indeed a problem. All modern standard circlips I have found are much thicker - about 2mm. There must be somewhere where I can find circlips that fit... Even Drags has some for BSAs and Triumphs, but without dimensions so in the end I not any smarter. At the moment I'm stuck and will keep on searching...

To the last post by Bob, I don't think you can/should grind down a standard ring down to thickness, as we are talking about a hardened steel, and at best one would loose the spring effect on the circlip.

If anyone has an idea where I can get those circlips or suitable substitutes, as well as the other bits I'm missing, please let me know. My dream of having the old girl running by next Spring can not be ruined by 3 circlips and a few other bits!

Thanks again for all the help here.
Gui

[Gui.dorey]

Before I forget, here for future reference the dimensions of the circlips according to my measurements (I measured the bore and groove in the cases):

Crankshaft circlips 1443-37: Dia: ~63,5mm or 2.5" , Thickness: as posted above 0,03" or ~0,8mm
Camshaft circlip 1464-37: Dia: ~47,5mm or 1.9" or 1 7/8", Thickness: as posted above 0,03" or ~0,8mm

[simon.holyfield]

I'm glad you are finding it useful Gui - I had noticed the audience numbers in Germany were high. Welcome to the forum!

There's a post about my cylinder head somewhere - you should have the larger studs by 1951, and you should have inserts in the plug holes too. On the 2119-49 timing chain stop, there is a picture here:

https://ariel-square-four.blogspot.com/ ... e-yet.html

It's just a simple bit of folded metal - you could make one in half an hour with a hacksaw and a file. On the dynamo strap pins, which I think are 2359-37, Drags have these or did I misunderstand you? These are the same as the ones in my engine.

[simon.holyfield]

I found these circlips which are nearer the thickness you need:

https://www.bearingstation.co.uk/produc ... 1300-1-3-8

[Gui.dorey]

Simes,
thanks!
I do have the larger studs and inserts in the plugs.

The stop should be easy enough to make myself. Those pins from Dags look right, although they have another part nr., but will work I'm sure. And those circlips are almost right - still they are too thick. The groove is really only 1mm or 0,039" at the most so at 0,05" they wouldn't fit. Grrrrrrr...

[KenGriggs]

There's nothing too technical about the dynamo retaining pins. Just a piece of bar the right diameter will do. They are a very light fit in the "eye" bolts, and are held in place by tension of the retaining straps when they are tightened up.