26-09-2019, 10:45 AM
(26-09-2019, 09:23 AM)Ruairidh Dunford Wrote: Check out the cam grind on this, was fitted with Maxi valve spring and is not fitted with liners.
Is that a crack in the crankcase too? Maxi valve springs or something with a similar seat pressure were pretty much a "must have" for 7000+ RPM with the cam grinds then in use when I was running a race car. Obviously this increases the load on the block joint; largely on the cam side. Never had a problem with this once the two outer studs in the tappet chest were extended past the cam through to the crankcase base. I have never used a linered block in anything other than a standard motor though. Are those Austin factory rods in your photo?
Most of the slippage/movement problems occur with dry linered Aluminium blocks, where the differential expansion between the steel liner and Ally block means that the liner will always be tighter in a cold engine that in a running hot one. For race use so-called "Top Hat" liners are often fitted so that the head gasket's fire ring sits at least partially on the narrow flange on the liners' top; a recess having been machined in the block face to ensure that the liner is still flush once it's pressed in.