[DeTomaso] Sodium valves

[B. SEIB]

Hi Robert
Sodium valves were a feature in the 375HP version of Corvette 327 engines
with fuel injection. I don't recall sodium valves being used in other US
standard production engines. Maybe some other exotic engines did. Later
valve steels and technology made the risks and expense of sodium filled
valves obsolete in HP engines. The idea originated in aircraft piston
engines back around WWII, I think, and was related to trying to cool exhaust
valves under high stress loads.

The 1971 Cleveland 351-4V engines in Panteras (and Mustangs,etc.) had high
compression closed chamber (quench) heads, single point distributors, small
square bore 600cfm 4300A carbs and 2 bolt mains. The Boss 351 was the only
351C to get 4 bolt mains, dual point distributor and the large spreadbore
Motorcraft 4300D carb in 1971 along with high compression CC heads.

Some people have said that some 1971 4V engines found there way into very
early 72 Panteras, but probably only in early January 72 cars. The 1972
Cobra-jet engines would have entered production in Sept of 1971 and by the
end of 1971, DeTomaso was likely to have used their engine stock on hand and
have received new Cobra-jet engines from Ford. I understand DeTomaso was
generally receiving engines only about a month or so after they were
produced in the US plant.

1972 Panteras came with Cobra-jet engines that had open chamber (lower
compression) 4V heads but with 4 bolt mains, dual point distributor and
large spreadbore Motorcraft 4300D carb. This was the strange result of Ford
trying to recover some of the power lost to stricter emission standards for
1972. The compression had to come down for unleaded gas and Ford upped the
RPM to try to get some oomph back. They retarded the cam timing and hopped
it up a bit to get the power at higher revs, thus the dual point and 4 bolt
mains.

1973 and 74 went downhill from there, with increasing emissions and lower
compression.

So...the best heads were in 1971, but everything else was better in 1972.
Unless you have a 1971 BOSS 351 engine, which never came in a production US
market Pantera. Pity that.

Barry