During disassembly of my 390 (1967 convertible) I found that the PO had but some kind of homemade reducer plate between the thermostat and the intake. After a bit of digging I've found that some 390s had a larger diameter thermostat opening and some had a smaller one. The local auto parts store only has the smaller thermostat in their computer for the 67 390 and yet I can say for certain it's not correct for my stock intake manifold since it falls right into the manifold.
I read that a 64 T bird 390 thermostat would work but that proved to be too large. Does anyone have a definitive answer for what thermostat to get for a 67 390 that's not the small diameter one?
I read that a 64 T bird 390 thermostat would work but that proved to be too large. Does anyone have a definitive answer for what thermostat to get for a 67 390 that's not the small diameter one?
