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MG Midget and Sprite Technical - 1275 main bearing caps

Hi,
I have started the rebuild of my engine and need some advice.
To get straight to the point, should I use tab washers on the main bearing cap bolts or not?

MGOC spares do not list them, Mini Spares Center say they are not needed but the engine had them when I dismantled it and Sussex Classics list them.

It is an early (12cc) 1275cc engine, +.040", balanced bottom end, Peter Burgess head (standard valves), SW5 cam, Peter May steel flywheel, 7.5" clutch.

Thanks

Dave
Dave Brown

Simple answer is no. I just used a bit of locktight on the threads.
Bob Beaumont

NO!!
never ever use lock tabs on anything that should be torqued!
The tab material is to soft to keep the proper torque good for long.

So either drill and lockwire or use a bit of locktight or torque dry
Onno K

No ...it.would not have come with lock tabs orginally, to my knowledge ayway

Arp, dosnt supplie them ither in there kits

Prop
Prop and the Blackhole Midget

YES!

According to my reprint of the BL parts catalogue, locktabs WERE fitted on 12CC engines up to serial number 1556. The bolt and the dowel also had different part numbers.

If your engine is that early, it may even have an EN40 crank.

If it was my engine, I would fit locktabs.

948 and 1098 engines used locktabs on both main bearing and big-end bolts.

The Moss catalogue also shows the parts...

D O'Neill

Just to add, the locktabs that Mr Derrington fitted to my 948 are NOT soft. They would laugh at a mere 60lbs.

But maybe those available now are different.
Nick and Cherry Scoop

It is never easy is it?
No, No, No, Yes!!

I will check the engine number (if I can find it, now where did I put it...?).

How do I identify an EN40 crank? Should I do anything different with an EN40 crank?

Thanks
Dave
Dave Brown

The crank will have the part no and material type on one of the webs. It should say either:-
AEG556 EN40B or
12G1321 EN16T

You don't need to do anything different other than cherish it.
D O'Neill

I have an early 12cc (number 1258) engine with an EN40B crank and it didn't have lockwashers when I stripped it back in the 1970's. The crank seems so hard it has never needed a regrind despite covering over 100K miles!.
Bob Beaumont

How do I identify an EN40 crank? Should I do anything different with an EN40 crank?

On one of the middle counter wieghts it will say EN40B or EN16T


Should I do anything different with an EN40 crank?

Yes there sure is...

If its an EN40B... sell it, buy a 2nd home in italy, and start enjoyng early retirement

Vizard has several pharagraphs on how there to be properly machined and treated...and it aint cheap

Good luck on that mega bucks lottery crankshaft

Prop
Prop and the Blackhole Midget

As to the tab lock washers.... im surprised by that.

so im sure this to is probably wrong also ... I wouldnt use anything less then grade 8 quality

Just my 2 pennies

Prop
Prop and the Blackhole Midget

I feel so foolish. I never noticed this before (see photo).
Thanks for the advice.
So the main caps would have originally had tab washers but the recommendation is a bit of loctite and no tab washers.
Dave.

Dave Brown

I had a similar problem with my 1500 mains, washers or no washers. After a long conversation with folks at Moss it became clear that it depends entirely on the type of bolt. With a 'stretch' bolt that you use once then throw out, no washers, tabs or locking is required. But with the plated 'non-stretch' (they both stretch but the plated one's not enough) re-uable bolts you use the washers listed as original equipment; they are hardened and sprung. That's the info I got from a member of staff at Moss who was previoiusly an engine builder by trade. So, unplated high-tensile 'black' steel = no washers/tabs while plated bright high tensile = O.E. washers or tabs as specified. I originally asked because in the 80s I built quite a few engines using tabs or washers or lock-wire. They were then unplated but the same as the modern plated ones underneath.
N.C. Nakorn

This thread was discussed between 02/06/2014 and 03/06/2014

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