Re: Cracked block- how serious is it?

Posted by DavidM On 2011/7/26 19:36:48

A little off topic but I would like to comment on the possibility of increased risk of block cracking due to use of valve seat inserts.
The block on my 1929 633 had been fitted with valve seat inserts before I got it. I reconditioned the engine at considerable expense and shortly after running it, it developed cracks between a number of inlet vales where there is a cooling passage On examination it was clear that the cracks resulted from the fact that the block had been weakened due by the machining necessary to fit the inserts plus some loss of thickness due to internal corrosion. Bear in mind that pressing in the inserts does not compensate for the loss of strength and could increase the stresses in the area due to the interference fit and if the insert expands thermally more than the block.
I don't like valve inserts and don't think we need them given that we do not use these cars as we would our everyday car.