Hi Guys, I have a 3.9 Rover block which needs the mains line boring, I also have a 300 crank so it would seem sensible to bore the mains to 2.5" and use the 300 crank. As a safeguard against future rebuild problems I want to use 300 main bearings and believe that this will entail line boring the mains by an additional 0.022". Problem is I'm having difficulty confirming this as most sources say that it's approximately 0.022". Has anyone done this and if so can they tell me the exact overall diameter that the mains will need line boring to. Thanks Rossco
You might also check with IgnitionMan Dave over at BuickStreet's Forum. Dave has installed a P76 crank in his 215" Buick engine. I believe he wound up over 300".
If it's a 3.9 2-bolt main block, the main bearing diameter is 2.3", the 4-bolt (crossbolt) 4.0 rovers have a 2.5" main bearing. If you have the small journal block, it's is better to have the crank cut down to match, and use standard 215 bearings. If you have the 4.0, +.010" oversize bearings are available from John Eales in the UK (http://www.beestore.co.uk/johneales/searchsite.html JE DEVELOPMENTS, not JE Engineering). Rick(wrench)
