is there a difference in the rocker arm ratio i have the following complete heads: 1231786 and 1246322 i head that some are 1.5 while others are 1.6.... any help would be appreciated
Wait hold up I'm wrong! The 1231786 heads likely have the 1.59 ratio rockers I mistook the first number for the stage 1 head number.
AFAIK, all the stamped steel rockers in 1970 are 1.55. My 71 Chassis manual says 1.60. My 72 and 74 Chassis manuals say 1.55. The earlier 67-69 oil through the head rockers were 1.59.
Stock 1970 - 1972 rockers would be cast aluminum, 1.59:1 Stock 1973 - 1976 rockers would be stamped steel, 1.54:1 I'd take those ratios (factory specs) with a grain of salt. Tommy
Can anybody confirm this? I thought the '69 and earlier aluminum rockers were 1.59 and the '70 and up bathtub aluminum and later steel were 1.55. I would agree that the 70-71 were aluminum. Not sure about the 72's being aluminum or steel. If the '71 chassis manual says 1.60 that lends credence to the '70's aluminum being 1.60/1.59. There are even two different steel units, the earlier wide and later narrow body type. I was just measuring some narrow steel rockers on the head and they surprisingly came out to very close to 1.55. Someday I'll have to get around to measuring some '70 aluminums.
The difference is so small that I have to wonder "who cares" about the rocker ratio. I bet there's more difference in ratio from a "good" valve job to a "bad" valve job, based on valve tip height and valve-train geometry; and one has to wonder about rocker-to-rocker consistency as well. I'd be more interested in durability than rocker ratio in this case. I've heard the stamped-steel rockers are a poor choice for performance use--the pushrod sockets are weak. Mind you, I've not confirmed that independently. "I" have a deep distrust of aluminum rockers, so I'm surprised that Buick people seem to like them.
