New Robert Shaw Thermostat has a raised rib on the radiator side that measures 2.125 inches OD.
Issue is cast water passage hole in Tstat housing is only ~2 inches ID causing the Tstat not to seat properly.
I likely just add a profile to the housing with a die grinder to allow the Tstat flange to nest in its intended seat but wondering if anyone else has run across this?
Standard Tstat fits fine with no modification.
Thx.
There are two sizes for the thermostat. Early cars used the large one. Late cars used the smaller one.
Pictured is a 351C thermostat.
Understand early vs late versions.
This is the early application with larger flange format - the 370 series.
Housing is aftermarket but correct for application.
Tstat and housing application shows correct for early FEs.
Sealing Flange Outside Diameter is correct at 2.49 in (63mm).
351C uses 333 series and is dimensionally different.
In any case, fit and function should be good with the added clearance in housing for the Tstat radiator side raised rib.
Tstat mechanically opens toward the engine (Intake manifold) side - no constraint in that direction. This was verified by inspection (observation) while Tstat emersed in hot water to test operation range.
Not seeing a problem.
