30-04-2021, 09:10 PM
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.
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.