Hello everyone... I picked up a halfway decent 1969 350 H.O.?.. And seller told me engine was rebuilt... Well first thing is very rough idle and veh has spark knock bad with 93 octane.. So since im new to this engine i got some numbers off Heads's ,,Intake,,Carb,, Block... Heads are Cast number 48,, Block Date code looks like L288, which means the block was cast on Dec 28, 1968. Block casting number is 9790079 -So it looks like its not the orig block, but that fine by me...
So after chasing spark knock and rough idle and 15 inch manifold vacuum and i then find initial timing at 4 degrees ATDC ..(mallory Uninite Dist) So i pulled the Mallory Distributor out and put in old reliable G.M. HEI.. Set initial timing to 8, and i see a max timing of 35 degrees with vacuum advance unhooked.. So im still chasing 15 inch of manifold vacuum and rough idle and spark knock... Then out of no where i see vacuum gauge bouncing very fast at idle but not going over the 15 mark... So im assuming i have worn out valve guides ??????????
Thoughts guy's... Im thinking my best bet is to get rebuilt heads they may lower compression or new ? But gotta same some money so rebuilt may be my option.