27-02-2020, 01:49 PM
Hi John
Back in winter 2003/2004 as a newcomer to A7s and following a broken crank in my 3 bearing engine, I built a replacement 2 bearing engine from all sorts of new and old parts, including a 1935 crankcase and a nice new Phoenix crank. One snapped crank was enough for me. I remember being a bit surprised that the con rods were rather offset sideways relative to the pistons, but as there was nothing I could do to adjust this and the engine seemed to turn over freely I put up with it.
To digress a bit, I had already been through the trauma of a crank assembly (no rods yet) which resulted in a crank very stiff to turn. This turned out to be due to a massive preload of about 12 thou in the front main. After learning belatedly about matched and unmatched bearings, I fashioned a suitable inner race shim which reduced the preload to a more reasonable 3 thou and things freed off remarkably.
This engine (my first and only Seven engine build) has now completed over 10,000 trouble-free miles in 16 years. So I would be inclined to leave yours alone unless of course you need to dismantle it for some other reason.
Cheers, John.
Back in winter 2003/2004 as a newcomer to A7s and following a broken crank in my 3 bearing engine, I built a replacement 2 bearing engine from all sorts of new and old parts, including a 1935 crankcase and a nice new Phoenix crank. One snapped crank was enough for me. I remember being a bit surprised that the con rods were rather offset sideways relative to the pistons, but as there was nothing I could do to adjust this and the engine seemed to turn over freely I put up with it.
To digress a bit, I had already been through the trauma of a crank assembly (no rods yet) which resulted in a crank very stiff to turn. This turned out to be due to a massive preload of about 12 thou in the front main. After learning belatedly about matched and unmatched bearings, I fashioned a suitable inner race shim which reduced the preload to a more reasonable 3 thou and things freed off remarkably.
This engine (my first and only Seven engine build) has now completed over 10,000 trouble-free miles in 16 years. So I would be inclined to leave yours alone unless of course you need to dismantle it for some other reason.
Cheers, John.