Fan shroud cooling capacity.

[Passatman]

Good day Guys,

Which is better in cooling a 2554cc ( 101 x 78.8 ) t1 engine, 36Hp fan shroud or the late 70's doghouse fanshroud.

[Marc]

An actual OEM 36HP shroud wouldn't even make the list (nor would one fit - what's often referred to as "36HP" is actually early non-fresh 40HP, which have the correct dimple along the bottom edge to clear a late case). Such "singleport" shrouds rely upon the presence of a cooler inside to aid with the even distribution of air, and they don't do a very good job of it - but without the cooler things are even worse, since more air goes to the base of #3 & 4 cylinders leaving less available for the heads.
If you're referring to an aftermarket shroud with the correct internal vanes to allow proper airflow to the left side (with no "singleport" cooler inside), it's essentially the same as a stock `71-`74 doghouse shroud but with more dual-carb clearance and less-efficient (or no) freshair hose ductwork.
The doghouse cooler is often sufficient; if more oil cooling is needed, that can be provided by an additional cooler in-line with a full-flow oil filter. It's also feasible to "stretch" the doghouse tin out to make room for the larger Type IV cooler, although there isn't 100% consensus that it's worth the effort.

Be aware that the width (and therefore the CFM) of the cooling fan was increased ~¼" with the advent of the doghouse shroud. The wider fans don't fit well inside early shrouds but most aftermarket ones will accommodate them.

[Passatman]

Thanks marc was thinking of the scat 36HP shroud.