Some more trivia from an old guy:
What does the so called term vapor lock mean? Think about this: When you boil water it turns to steam or VAPOR, When you boil Brake Fluid it turns to VAPOR. In 1962 drag racing my C/G 38 Chevy. At the end of the 1/4 I had NO BRAKES. Kill the engine and in a few seconds I had a full pedal.
Cause: Headman Headers blowing hot exhaust on brake line.
When you boil gasoline it turns to VAPOR. A 7040205 will no operate on VAPOR, Must have liquid.
So I Call my Brother in law Bill, From Mich, He says call my friend BOB, I call Bob and answer many questions for this Bob guy. He tells me on the phone the problem with my 70 454. So I do what this Bob guy tells me to do.
After I follow Bobs instructions, I now have no more Vapor Loc.
FACT: My one owner LS-5 never got hot or had vapor loc. So what changed.
I had a BAD Eaton Fan clutch.
Fact #2: 1970 " A " body Chevelles all models had an Airflow Ducted engine bay. What the hell is that? I means, All the air that enters the engine bay is FORCED to EXIT ( By road speed or by the engine powered exhaust fan.)
Fact#3: A 1970 engine bay is designed to have the Super Heated Air Exit at the rear of the Lower right & Lower left cast Iron manifolds.
Fact #4: Changing any factory under-hood installed items (rubber seals and such) , So when you re/engineer your engine bay cooling system, And you also think a lot of what this guy just is a big load of Bull Sh!T.
All this stuff about duct work and sealed off engine bay stuff and moving " X " number of cubic feet of air per min. sounds fishy.
When your home A/C or your furnace is running. Use caution !
Remove the blower belt, ( You better have " Super Heat switches working " And then lets talk about Air Flow and Duct work.
Just some trivia, From an old Guy.
P.S. So you know, My B.I. law Bill was a boss at FORD the Wayne Assmb. plant for 37 years. The Bob guy I speak of was a Thermal Engineer for Chevrolet for 39 years. It is not verbatem, But close.