300J exhaust vlv

[66 Meteor]

Does anyone know the Mopar engineering reason that the 300J exh vlv 1.74" was not extended to the '64-'66 B head? Why did Mopar go back to the 1.60 exh vlv size? I see in '67 the larger vlv returned one the 440HP (915 head). What's the real story here?

 

[Cranky]

Go back to the 1.60 valve? As far as I know, the 1.74 valve showed up in 67 and stayed until the production of the big blocks ceased.

 

[62MAX]

Actually the 2206324 61/62 head had 1.74 valves as did the 62 300 H and 63 300 K

 

[Meep-Meep]

If I had to venture a guess I'd say the larger valve on the 300 was part of the engine perf option package because I think those had some very strange free flowing manifolds. Then later in 67 they came back because of the then new 440 HP. And possibly after that they felt no reason to change back.

 

[62MAX]

The 63/64 J & K exhaust manifolds were big very efficient individual runner cast iron header type manifolds with 4 bolt Max Wedge type outlet flanges.They actually had an individual support bracket that went from manifold to block do to their weight.Had a set years ago that I wanted to use but they won't work on a B-body,they come down right on top the torsion bar.Today they are hard to find and very expensive.