Im always surprised at the number of newer guys that don,t realize that one of the forward facing bolt holes intersects the fuel pump push rod guide hole in the chevy block, IF your not using that hole for the old style front motor mount you need to get a 1/2" long or at most 3/4" 3/8NC bolt with THREAD SEALER on the threads installed in that hole or that hole will puke oil constantly at any rpms over idle speeds,but don,t place one in that threaded hole over 3/4" long or it might bind up the fuel pump push rod , many of these holes don,t leak from the factory even if they don,t have a bolt because the threaded holes filed with paint, but you can be quite sure it will leak once the blocks been carefully cleaned during a rebuild, if the threaded is holes not plugged with a bolt and with sealant on the threads, as the paint in the threaded holes is sure to be loosened or removed by a good block cleaning
viewtopic.php?f=62&t=1430&p=3168#p3168
the threaded hole might have been plugged with paint, a bolt or sealant that just is no longer there, I have seen several blocks with that hole plugged with a thumb full of silicone thats been painted over, and theres was rather obviously no bolt sealing it, but a 1/2" - or at most 3/4" 3/8"NC bolt with sealant on the threads and a star lock washer is really required if your doing it correctly
viewtopic.php?f=62&t=1430&p=3168#p3168
the threaded hole might have been plugged with paint, a bolt or sealant that just is no longer there, I have seen several blocks with that hole plugged with a thumb full of silicone thats been painted over, and theres was rather obviously no bolt sealing it, but a 1/2" - or at most 3/4" 3/8"NC bolt with sealant on the threads and a star lock washer is really required if your doing it correctly