Rhoads lifters are an ideal lifter for the Buick engine where rough idle, low fuel economy and poor driveability are the results of a larger cam. Rhoads lifters give the illusion of running two different cams at the same time. The lifters “bleed down” at low speeds through an oil orifice to make the cam act smaller than it is. Then at higher RPMs the lifter expands to let the cam be it’s actual size.

--  Prior to 1970 Buick oiled their rockers via integral passages on the cylinder block and cylinder
heads. Oil was delivered through these passages direct into the rocker shafts. The oil was then
distributed to each rocker by a feed hole in the shaft at each rocker position.
-- 1970 and later Buicks oiled the valve train in the more conventional manner: up through the
pushrods.
-- In order to use TA 1405, TA 1410 or TA 1415 lifters in pre 1970 engines a few simple changes are
necessary. Other than changing the lifter to the later model you will also need to use a hollow
pushrod (`70 and later) and `70 and later rocker assemblies. If you would like to retain the earlier
style rocker assembly; TA offers Hybrid adjustable pushrods that incorporate the smaller radius tip at
the lifter and the larger radius tip at the rocker. You will also need to block the oil feed passage that
delivered oil to the rocker shafts. Block this passage in the head itself or in the cylinder block.