91 octane to stop vapor lock?

[Blackmamba]

For what its worth, I would like to ask, what degree Thermostat are you running? I originally had the 195 degree thermostat, obviously hotter, so I swapped it to a 180 degree thermostat, stock for my 1970 198 slant six. I noticed a pretty decent difference in overall engine temperature looking at my temp. gauge.

I would also recommend making sure your cooling system is good to go, and your carb settings; mixture, idle speed, and all necessary filters are checked.

Heat shields, electric fan?, all recommendations on this page are perfect for your situation.

It sounds like a lot, but checking all these aspects in your car can save gas and money, and save you from aggravating hot start problems.

Yeah, I first thought about the cooling system. Rad and liquid were good. I am missing the fan shroud though. My mechanic replaced the thermostat and frost plugs and now the needle is steady in the middle. Not sure what degree thermostat.

Going to look into a heat shield. Manual switch fan would be nice.

 

[2 Darts]

I have a stock 198 Slant six (71 Scamp. Would filling up with 91+ octane (no ethanol) alone been enough to stop Vapor lock altogether?

No.

Octane is a colorless liquid that will boil around 125º F. Octane Ratings are only a measure of the fuel's tendency to burn in a controlled manner, rather than exploding in an uncontrolled manner. Explosion in an uncontrolled manner in an engine is what is more commonly called knock or "dieseling".

The best way to stop vapor lock in my experience was when I wrapped the fuel line with thermal insulation between where the line goes vertical to the cylinder head to where it passes over the intake to the #1 cylinder. I exercised my redneck tendencies to bind it down with coat hanger wire.

 

[desy500]

A lot of this sounds like the problem I just ran in to. First 85 degree day since I owned my slant 6. I thought the electric fuel pump was cutting out, after it stalled out, pump wasn't pumping to start back up.10 minutes later it would start up and run for a while,then stall again, no fuel in the clear filter. What do you guys think, vapor lock?

 

[nm9stheham]

^^ Potentially a symptom of vapor lock... but an awfully bad case if it stalls while running. Seems more like a bad pump, plugged line from dirt and crud in the tank, a cracked rubber line from the tank, etc.

 

[Blackmamba]

No.

Octane is a colorless liquid that will boil around 125º F. Octane Ratings are only a measure of the fuel's tendency to burn in a controlled manner, rather than exploding in an uncontrolled manner. Explosion in an uncontrolled manner in an engine is what is more commonly called knock or "dieseling".

The best way to stop vapor lock in my experience was when I wrapped the fuel line with thermal insulation between where the line goes vertical to the cylinder head to where it passes over the intake to the #1 cylinder. I exercised my redneck tendencies to bind it down with coat hanger wire.

Thanks for the info.
I must be more redneck then you. I wrapped the old metal line with foil before re-plumbing the whole damn thing. no joke