318 MAX fuel economy builds?

James Clews said

Back in the seventies I had an Ex police 265 hemi six Valiant charger. I put a pacer factory 4 barrel manifold on it and factory headers. Those factory 4 barrel manifolds were very long runner manifolds with a water heated plenum in them. This car ran 14.7 sec qtrs @92 mph . The camshaft and exhaust system were standard police spec. Carb was a vac secondary holley 600 cfm.
This car ran exactly the same as the original 2 barrel and fuel economy was as good if not better than the 2 barrel. The only thing I changed when taking it to the track was to disconnect the water heating and going up 2 sizes in jets.
Until I put the water heating back on after the drag racing it would have a slight dead spot off idle but the water heating fixed that.

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That’s interesting and not surprising. If you can’t get all the fuel vaporized in time you can certainly get a lean spot in the fuel curve.

It’s also interesting to note that there is always a puddle in the bottom of the intake manifold and that’s what fuel the engine runs on.

When manifold vacuum goes to zero (or close to it) the pressure change takes the atomized/vaporized fuel and converts it back to a liquid.

SuperFlow says it takes about 100 engine cycles to recover from that.


EDIT: BTW, was it any quicker/faster with the water not heating the intake??