Running Hot on the Highway Options

[NJ914Guy]

My car is a 1973 914 2.0 running dual Weber 40 carbs, an Aircooled.net SVDA vac advance distributor (vac port connected to dual carbs) and a Pertronix electronic ignition module.

Here in NJ, on a 80-90 degree day, the car runs great on the back roads ranging from 30-45 MPH. Using the dip stick temp gauge, she runs around 180-195 for oil temp. If I take her up ont the highway and run the car at 65-80 MPH for 10-20 minutes, the temp will run up to 220-240, based on the outside air temps, which seems too hot.

I assume that since I am fine on the back roads, my flaps and fan are clear and working fine? I do have 100% of the factory tins in place, and from 180-240 degrees, the car runs strong at all temps.

I am thinking that I have a problem and would like to rule out some things. Here's my list of things to try. Please feel free to comment or make additional suggestions.

1. Change oil. I am running 10W-30 now. Have some fresh Brad Penn 20W-50 on hand. Could an oil change help?
2. Drop the oil screen and check for any sludge or blockage which may be impacting oil flow.
3. Check timing on the SVDA dizzy. I am wondering if it's advancing a little too much on the highway? Per John's instruction, when we installed the dizzy we set timing to: 38-45 Total Advance (hose connected) @ 3500 RPM.
4. Pull spark plugs and check for lean conditions.
5. Check carbs and idle jets. Not sure what's in there, but I hear that I want idle jets of 50.

[NJ914Guy]

What's a good range for O2 on a carbed 914?

[ape914]

What's a good range for O2 on a carbed 914?

depends on your engine, but in cruise a bit on the rich side is ok on an aircooled car, else they will run hotter. you might try around 12.5:1 and see if that effects your temps. you got carbs, so go one jet size bigger and see what happens. a spark plug reading can help you. if your carbs were set for the old gas, they will run too lean with todays oxygenated fuel.

old gas =gasoline

new gas = gasolean

[ChrisFoley]

but in cruise a bit on the rich side is ok on an aircooled car, else they will run hotter.

That's actually a common misconception.
The engine will run plenty cool and get better gas mileage during light throttle operation if the AFR is between 16-17:1.
For full load operation you need the mixture no leaner than 13.2:1, with 12.5-12.8:1 being used more often to create larger a safety margin.
Anything between 14-15:1 will make the heads run hotter.