checking flow of coolant

Clutch fan? Might be time to change the clutch. Just because it's turning doesn't mean it's providing sufficient air flow.

I would have to agree with Jimv there. If it's cooling when going down the road and not when sitting still, that would mean that the fan is not moving enough air at idle. This is usually a cluch fan problem, which is not always easy to fix. I have had to go through as many as 3 before I got a new one that was actually good. You might consider switching to an electrical conversion as it will both lower the load on the engine and do much better at moving the air at low speed.

It's also possible that the water pump is not moving the coolant well enough at idle, but that is far less likely than the fan based on the symptoms.

It has no clutch.

This, I do not understand. You mean that it turns too slowly causing insufficient airflow?

It spins quite fast at idle, and the flow is very noticable. The airflow is towards the engine, though, not towards the radiator. Is this the correct direction?

Thanks,

Bram

185 is perfect ... under that you have incomplete combustion ... also not enough heat to burn off any moisture the motor takes in ... over 200 is not good either .. motor oil starts to char at 215 ... with the warm weather this time of year try a 180 degree thermostat ... a radiator is a heat sink and nothing more .. it has a certain ability to dissipate heat ... check and count the number of cores in yours ... 2 is common .. 3-4 are available .. you can probably see the unused rows on your radiator side tanks ... a 4 core is the ticket for a good running small block , 3 is ok =BF ... if you want to check that indeed your coolant is circulating , just undo ( when cold ) the cap on the radiator , let the car come up to temp at idle ... when the thermostat opens there will be a surge of coolant ... at what temp that happens is the key ... it should be with in 5 degrees of the thermostats temp rating .. there are hi-flo thermostats , and water pumps made by many aftermarket co.'s that might help also .... more h.p. means more heat ... a 2 core radiator might do a 2 barrel 305 nice ... add a 350 , headers , cam , carb , etc. .. more power =3D more heat .. all produced inside the same block of iron=

.. which now wants a bigger heat sink .... and the of all , get yourself a mechanical temp gauge ... factory electric one's , now some

30 odd years old are nothing to believe in ... the mechanical type read's if the motor is running or not ... heat soak ( full temp. motor shut off ) should never go past the 215 mark for the oil/motor's sake .. the 185 mark is like a sweet spot for'a Chevy .. you'll feel it ! .. just don't smile or the VAT police will get ya