Steven24f

Alright so I have a 1979 corvette with a BBC 540 and I can’t get the thing to run cool.
I have a 4 core champion radiator running a 80/20 mix with water wetter added to it.
Dual maradyne electric fans with shroud about 3500cfm
Stewart stage 2 aluminum water pump with a march under drive pulley.
Timing is set at 18 initial with mechanical advance all the way to 38 at 3000rpm
165 thermostat that is operational and doesn’t stick(confirmed in boiling water)
Car runs great but temps consistently climb past 220 with ease. Am I missing something?

Mooser

Have you double - triple checked the accuracy of the gauge?
I'd start there before looking at anything else.
M

HeadsU.P.

That water-pump you are using, by chance is that a reverse rotation?

Bikespace

Have you pressure tested your radiator cap? Checked for a spring in your lower radiator hose?

79 has an optional lip spoiler that only a few cars got. If you are overheating at speed, and the rest of your foam is intact, this might help.
https://www.ecklerscorvette.com/1979...-314844-1.html

Finally, have you checked for a head gasket leak (either by running without the cap, or testing for exhaust gases)?

Steven24f

One fan is wired to turn on at 175 and it does so when gauge states 175. Using that as a confirmation of the gauge working properly.

Steven24f

The water pump is standard rotation I confirmed that prior to ordering it

Steven24f

I have not pressure tested nor sealed the radiator off but I do have a pace car spoiler so I’m gonna get those done and see what happens thank you

Rescue Rogers

Having a spoiler/ splitter, a sealed airbox in front of the radiator and all the radiator seals are key to keeping it cool...then its flushing it and making sure the fans are running in the right direction...if they are on the inside and you installed pushers it ain't gonna work....if it overheats at speed that's because of an airflow problem, if its in stop and go traffic it's a bad fan combination, non working fan and or a shroud issue, the fans all need a shroud that seals against the radiator but allows airflow at speed

If all that works pull your thermostat and see if it goes away...ive had sticking stats before

OMF

I agree with the others about the seals are a must have.....although I'm missing the top one on mine and have no cooling issues....I'm running a small block....540 cubes are a bit different
Pic of shroud and fans would be helpful. Many times it's the shroud that's the problem... either it's not big enough and encompassing the whole rad, or the shroud is to close to the fins and it doesn't allow free flow of air through the whole rad. There was a recent thread on this very issue.

Keep us posted...

SteveG75

- Make sure you have all the seals.
- Get the spoiler extension
- Get rid of the under drive pulley. You need as much water pump speed as possible.

4-vettes

I goggled the brand of fan the OP mentions he has. Most have no shroud, some have a flat pan style shroud. I had tryed one of those once. Terrible air flow.
Get some C5 Corvette fans. A little bit of trimming and they fit up beautifully. And the built in factory style shroud really works.
You simply can't beat the OEM stuff. CFM numbers can sound impressive, but it's the design of the shroud that actually moves the air. And in the correct way both with fans running and not.

Steven24f

*Update- decided to pull some timing since it required the least amount of work on Mother day. Initial timing set at about 10 and idle was brought up to about 700-800 in gear after that she idled in place for 30 min didn’t pass 200. I’m gonna still go ahead and swap out to a 185 thermostat and go forward from there. Definitely have to seal around the radiator next. I do have a pace car spoiler on the car so that’s gonna help as suggested while driving.