Fitting new shells

[Charles Levien]

I recently had my engine out (1937 three bearing) fit a new rear main oil seal,clutch linings and recut valve seats etc — I didn’t look at the bottom end. Having got the engine back in it became apparent that one or two big ends were, shall we say, drawing attention to themselves. I couldn’t face taking the engine out again so ( with apologies to our Welsh/Yorkshire friends) resolved to become an oily coal miner and see if I could fit new shells from underneath. A couple of new ramps at half price from Halfords helped and after an hours work the sump and gauze were off. Removal of the end caps revealed a good deal of wear and cavitation in the shells so a day later I was back with a set of new shells, big end bolts and lock nuts. Then the fun started — I don’t think I’ve ever had such a fiddly job to do in my life as trying to get those new bolts into place from underneath, not helped by them being a tight fit. In the end I used the old bolts with new nuts, torqued up to 18lbs which I reckon is tight enough. 
Would I do this again? I guess I would but fitting new bolts is really a job to be done from the top before fitting the block back. Level of happiness having got job finished — massive!

Charles

[Chris KC]

Well done Charles, just goes to show that pleasure is in proportion to effort expended!

I seem to recall being one of those who encouraged you to attempt this, and I feel obliged to confess with hindsight that it must be easier on my car as the bolts go in from underneath into helicoils in the rods, if I remember correctly. This is one time where a deep sump can be a pain too.

[Colin Morgan]

Hi Charles

When I had one big end to replace this winter, I did it from underneath, and yes it was fiddly getting it back together and the Nyloc nuts on and torqued (also to 18).  I had to take the head off so I could remove the piston and con rod to replace the bolts - on my car the old ones were in very poor condition - stretched and twisted - and also corroded into place, so I had no choice.  

There is a lot of satisfaction when it is all finally together and back on the road.

Regards,
Colin

[Nigel was in Brittany]

Excuse my ignorance, are they actually nyloc nuts or stiff nuts? , many years ago when I rallied a Twin cam Escort it threw a rod when the nuts let go, I don't know if they were nyloc but weren't the split pinned type, surely when the oil gets hot the nylon would melt?

[Steve Jones]

...........surely when the oil gets hot the nylon would melt?

The oil doesn't get THAT hot! 

I've used Nylocs in engines ancient and modern for nearly 50 years and never found that a problem.

Steve

[Colin Morgan]

Hi - They were Nyloc nuts - as advised elsewhere on the Forum, and seem to work fine.  The different grades of Nylon generally melt at over 200 degree C - the oil being sprayed around in the crankcase shouldn't be that hot? - Colin

[Bob Culver]

I gather these engines have waisted bolts.For those who have done this on other cars without effort perhaps someone more familiar than me can explain the complication introduced by this feature. Not certain how the lower shell is manipulated into place

[Ian Williams]

There is no complication, the bolts are not waisted they simply have a small flat on them to clear the shell.

[Ruairidh Dunford]

Quite correct Ian, example shown here: https://www.theaustinsevenworkshop.com/p...g-rod-9359

[Bob Culver]

Thanks fellahs. Did not realise they were that crude. 18 lbs ft seems plenty! Those exotic ultra HT bolts on the earlier engine would seem a bit of a luxury!