Nascar Engine Phoenix Craigslist

why does the R5 block use .870 lifters?

From the CL ad:


This is the list of parts I have:

MOPAR R5 Block. NEW never assembled. 4.170" bore, 8.85" deck height, .870" lifter bores. Cross bolted, 4 bolt main bearing caps. This block requires final finish honing of the cam and main bearing bores, and some deburring. Includes plugs for water jackets and oil squirters for piston cooling. (Summit sells this block new for over $4900, but you may find a block on Ebay for $1200 or so.)