Big ends

[Hedd_Jones]

You say that Chris. When I was 20 I spent my 'life savings' on a 1935 APD Opal. Chrome rad job. In bits but complete, bodywork akin to my currently for sale chummy. Solid but agricultural. Engine allegedly 'rebuilt'. I believe it was 2 grand.

I did the running gear, got stuck into the engine to find it so tight I could barely turn it. I took off the sump to find it had shells, but the caps had been filed, and it had clear gaps between the rod and cap!. I cant remember if it was a 3 bearing job, but I guess it must have been.

Loosening the big end nuts a little had it turning fine. So I used feeler gauges, measured the gap, made up some shims from fathers bestest shim steel. And reset it all tight on the shims, but used old school castellated nuts. It was still a little tight, but with it ratchet strapped upside down to the bench (with no head) and spun for 5 or 6 minutes using a gut buster drill, while pouring oil manually on everything, had it loosen off significantly.

I did briefly start it and ran the engine, and it sounded fine and didnt tighten up. But I then bought a steam roller, and therefore needed to convert the tourer to cash and so It went very soon after.

I have seen the car a number of times since, next time I shall perhaps ask the owner about the engine.

If its yours A Royal Blue APD 'Opal' 1935. ATT 772. Id love to know what you find when you take the sump off!. Or indeed if you have ever had any engine trouble....

[Steve kay]

Oh dear, I seem to be having computer problems. First of all I was told that I had logged off and had problems returning, now the well composed and wholly coherent reply, well my muttering, has disappeared. Come back reply, thanking everyone for forum answers, for messages and phone calls! Too late for a detailed technical response, but if I can get onto the forum in the morning I will reply. Meanwhile many thanks to all.

[Chris KC]

That made me laugh Hedd! Many such dodges were employed 'back in the day' to keep A7's going & side-step expensive repairs. I remember chatting with one former owner who found his bearing shells had been packed out with chamois leather...

[Bob Culver]

If I had a set of otherwise perfect rods ruined by filing I would not hesitate to file further for shims. The exact requied bore dia is easily measured. Pieces if nail or wire can be used as bore gauges; more accurate than two different micrometers. if shims are corretly positioned then filed flush can acuurately reposition.
When young I can recall tales of professional mechanics towing cars around the block etc to free them. From my observations a huge proportion of defects in older cars are the result of "expert" mechanic attention.

[Steve kay]

Many thanks to the team who sorted out computer problems last night, and many thanks to those who set down their thoughts on big ends.

What to do? Always mark up each paired  rod and cap, don't rely on markings just visible if you peer at them as they may be fictional, even the most reliable engineering shop may not mark everything.  White marker must be deployed. With the crankcase on its side, watch whether rods on the relevant journals will slowly sink downwards or can be gently pushed with a finger, if so they are fine. If rods are very stiff and immobile, do not panic. A bump on the very soft white metal will lock up the bearing. Get the engineer's blue down from the shelf and investigate the spot causing the problem. Then get the scraper out of the toolbox, or if feeling big fingered and arthritic,  get a pal to scrape the bearing till it fits. The entire bearing being locked up tight should not have happened with an engine that had previously been used. Comments vary in how to deal with that. Whilst I have seen bearings packed between rod and cap on more robust machinery such as steam or stationary engines, I did not think that would be suggested for faster revving and small kit such as the Seven engine. Experience quoted here indicates one can get away with it but how does the oil film continue across the gap in the bearing surface?

The benefit that us owners and operators of Grey Porridge enjoy is the helpful enthusiasm of fellow Seven owners. Having some slight anxiety about something, a question can be asked here, and then comments, emails,  messages and phone calls share knowledge and experience. My sincere thanks to all.