Thermostat housing

[KR500]

What was the original thermostat housing on a 1966 GT350 with a small letter S2MS intake manifold with a thermostat pocket? Would it be the C4OE-A housing with out the thermostat pocket or the C5OE-A with the thermostat pocket ( double pockets? )?
Thanks
Rodney

[Bob Gaines]

What was the original thermostat housing on a 1966 GT350 with a small letter S2MS intake manifold with a thermostat pocket? Would it be the C4OE-A housing with out the thermostat pocket or the C5OE-A with the thermostat pocket ( double pockets? )?
Thanks
Rodney

The C5OE-A housing came into use by Ford approximate March of 1965. Before that C4OE-A .So the 66 would use the C5-A.given you are working on a 66 the book Bob Mannel wrote "Mustang and Ford Small Block V8 would be a very good wild investment.FYI that goes for any GT350 owner 65-68.

[KR500]

Bob
Thanks for the reply. I have had Bob Mannel's book for many years and saw the C5OE-A for the 66, but it does not address the GT350's. My questioning is with the C5OE-A housing as there would be a double thermostat pocket. You would think that combination wouldn't seal very well.
Rodney

[Bob Gaines]

Bob
Thanks for the reply. I have had Bob Mannel's book for many years and saw the C5OE-A for the 66, but it does not address the GT350's. My questioning is with the C5OE-A housing as there would be a double thermostat pocket. You would think that combination wouldn't seal very well.
Rodney

The C4 will also work but the C5 was what used.

[Bob Gaines]

FYI the same style thermostat with the recess for thermostat was used on 67-68 S2 and S7 GT350 aluminum intakes with no special sealing problems ether . 

[gt350hr]

 A "loose fitting" thermostat is of no consequence when you consider the 3/8ths hole next to it ( bypass hose). Plus "most" gaskets swell when exposed to antifreeze. The C5OE was used without issue. Manifolds were made to allow use of either water neck as they were sold over the counter too . (As  we all know)
  Randy