According to the Team Buick website some 350 cylinder heads from 1967-1972 oiled through the pushrods. So if putting these 1967-1969 heads on a 1970 350 block do you still need to plug something up in the head? Head Cast #YearDisplacement123265071? 350 1233472*67-72 350 1237650*70-72 350 1238145*67-72 350 123347267-70 350 1237650*70-72 350 123774970-76 350 123814568-74 350 124014370-71 350 1241861**72-80 350 1242145*72 350 1242556*70-80 350 1243452**72-80 350 124771670-77 350 138254668-69 350 1382546*68-74 350 138272068-70 350 2250523673-80 350 22505238**72-80 350 243452**75-79 350 * Oils through push rods ** With A.I.R. 350 heads are 58cc
Tap and put a little threaded plug in the oil transfer hole in the block IF your using “thru the pushrod oiling” I’m sure someone else can describe it better than me on here
67-69 engines oiled through the block, and heads. Starting in 1970, engines oiled through the push rods. The early engines had a hole in both block decks, and corresponding holes in the cylinder heads. In later blocks, one hole was eliminated, but not the other. The later head gaskets blocked the oiling holes. That wasn't a problem with stock oil pressures, but for higher performance pressures, it could be a problem. Block the passage ways at the block deck and be done with it. See post #8 in the BBB oiling mods thread, https://www.v8buick.com/index.php?threads/400-430-455-block-id-prep-and-oiling-mods.214613/ Pretty sure it applies to the SBB as well.
