23-09-2019, 11:06 PM
Blueprint of conrod published a few days ago with centres spacing.
It would be a pity to open good rods out to standard if life not to be long, as good rods precious and unless new any other crank to be used likely to be undersize. Crank life may not be long, especially if any cracks. The rear journal must show no sign of welding, brazing etc. All radii must be intact.
Rods were traditonally fitted to a snug clearance; soon increased as scraping high spots wore off. But good modern practice is a distinct small clearance, esp if crank truly round.
If reusing main bearings acceptable clearance is hard to assess. Almost any perceptible step on outer roller tracks is too much.
Angular contact races with unmarked tracks can be shimmed to restore nil clearance when back to back.
Main danger if unfamilair is breaking the crankcase lip and heavy handedness with threads generally.
There are a myriad pitfalls but anyone with an instinct for what is correct and good practice can spot many. A trawl thru the Forum helpful. Contact with someone Seven expereinced the ideal.
It would be a pity to open good rods out to standard if life not to be long, as good rods precious and unless new any other crank to be used likely to be undersize. Crank life may not be long, especially if any cracks. The rear journal must show no sign of welding, brazing etc. All radii must be intact.
Rods were traditonally fitted to a snug clearance; soon increased as scraping high spots wore off. But good modern practice is a distinct small clearance, esp if crank truly round.
If reusing main bearings acceptable clearance is hard to assess. Almost any perceptible step on outer roller tracks is too much.
Angular contact races with unmarked tracks can be shimmed to restore nil clearance when back to back.
Main danger if unfamilair is breaking the crankcase lip and heavy handedness with threads generally.
There are a myriad pitfalls but anyone with an instinct for what is correct and good practice can spot many. A trawl thru the Forum helpful. Contact with someone Seven expereinced the ideal.