So,

My car is a 1972 Oldsmobile Cutlass Supreme with the 350 4bbl engine & factory AC.
Its running good and @ 180-190°F almost all the time, which is fantastic.

But when idling for somewhat longer temps are climbing to ~ 230°F with the A/C off.
Have not tried with A/C yet because the compressor is currently bad. But i suspect it will climb up even more with A/C.

It currently has no thermostat in it and the radiator seems to be this one:
https://ecat.spectrapremium.com/products/CU165
(Both has been done by a shop that i stopped bringing my car to.)

I think this radiator is maybe to small?
Especially since there is no thermostat i think it shouldn't reach 230°F when idling, right?

What do you think?
I think i should maybe get an oem radiator and thermostat installed?

 

If the engine runs at 180-190 with no thermostat, then something is amiss. My car with no thermostat ran at 140 even with full throttle blasts with the AC on.

Anyway, we need more information.
What kind of fan does it have - fixed, clutch, flex, or electric?
Is the shroud installed and intact?
What is the ignition timing set to, and is the vacuum advance connected and functional?

 

Since the system cools at speed, you have an idle airflow problem which is probably related to a worn out fan clutch.

 

Okay than its not as fantastic as i thought.

Clutch fan.
We replaced the fan clutch with this one recently:
https://www.summitracing.com/parts/gmb-920-2060

Yes it got a shroud that looks intact and original to me.

I dont know but it runs good & no funny noises.

I recently bought a timing light but i've never used one so far.
I just recently started doing my own repairs with the help of my dad because
of the bad experiences i had with "the professionals" at the "specialised shops".

I know it has an incorrect late 70s smog quadrajet on it.
I already bought the correct unit and plan to install asap but i do not think it runs to lean.

My bet is they bought/installed an undersized radiator and tried to compensate by taking the thermostat out.

 

Note what oldcutlass posted above. Running hot at idle but OK at speed typically is a symptom of not enough air flow at idle (a fan issue).

What throws me off is that you do not have a thermostat, so I wouldn't expect the engine to get to 180-190 at speed. As I said earlier, my engine with no thermostat wouldn't get above 140.

 

Normally i'm with you but i recently replaced the fan clutch.
Also as you said i get 40-50°F more than you without a thermostat at speed.

This is why i think undersized radiator.
But is the radiator i linked above undersized for my setup or not? (In general)
I already dont like the fact that it is an aluminum radiator.

 

Thats the specd rad replacement when spectra switched from a 4 row brass copper rad to an aluminum one.

same pn cu165

 

So is it sufficient or not?

I attached a picture i recently took for different reason.
It shows a little bit of the shroud and fan but not a lot, maybe it still helps though.

 

The operating temp at speed without a thermostat is dependent on what the outside air temp is and the capability of the cooling system . Remember once the thermostat is fully opened it really doesn't do anything.

 

I was having a similar issue with my car. Put one of these fan clutches in and a high flow 160 t-stat and problem solved. I wouldn't worry about your cruising temps with or without a t-stat. They look normal to me.

 

What's going on with the upper radiator hose? Is that some sort of splice?

 

if you want to go with a good radiator that looks factory and does a great job, I recommend the Spectra Premium CU351...it's copper/brass, and a little pricey but worth the extra coin. Do a search on Amazon and it should come up.

 

So i should again replace the fan clutch instead of the radiator?
I mean if you guys think the installed radiator is sufficient than i'm not going to replace it...

That has also been done by the shop that replaced the radiator and took out the thermostat and i think is a good example for how much attention they pay to details.
I would call that butchered together. Well at least it seems to work...

 

I’ve heard of people doing that to the lower hose to prevent collapsing. Never seen it done to the upper hose.

 

I think i will look into timing, otherwise replace the fan clutch in hope that it solves the problem.
I still can go back to a rebuilt or nos radiator if nothing else works.

I would also like to stick a thermostat back in there because i think it can't be good without, especially if it is cold outside?

 

Use one of these either 160 or 180 depending on how cold it get where you are located. If it gets down to freezing where you live and you are able still drive it, I would opt for the 180. Where i live it’s usually pretty warm so the 160 works well.

 

Timing can contribute to an over temp issue and is worth checking.

 

I would defintely replace the top hose and thermostat as well as check the timing.

the rad shroud and fan location look good. Is it a stock 6 blade fan w ~3/4” inch space between the fan and shroud?

if it still runs hot and there is nothing blocking the rad, like ac components that are clogged or damaged (remove if not used) then i would try the better fan clutch.

the radiator while smaller than the OE radiator is aluminum which is more efficient and *should* be adequate for a relatively stock engine in good condition.

 

While your at it, I would check the timing. You never know....