I've swapped in a fresh standard bore 1970 455 into my 1987 442. I'm still using the stock radiator that was in the car. the engine runs great but over heats. With the thermostat out if I spray some water on the radiator the temp falls quickly. I feel I need a 3 or 4 core radiator. Any thoughts on this?

 

I'd put the thermostat back in, it needs the flow control. What are you using for a fan/and or clutch setup, a shroud? How stock is the engine? And lastly what temp is it reaching at idle and at cruise?

 

The stock engine was a 307 ci in that Cutlass. You now have 455 ci.... I think we all know what has happened here with an overheating problem...

 

 

Yea I'm ordering a radiator now. Lol.

 

It runs up to 220 with that radiator and a electric fan and shroud. Motor is stock with a high energy can and performer intake. Q-jet and a HEI. I'm getting a better radiator and a Taurus SHO fan.

 

Probably a good idea.

 

Related question: How small can a radiator be for a bbo?

It turns out my stock radiator (which was not having trouble keeping the engine cooled, but had nasty brown gunk only at the lower hose connection so I took it in to be cleaned) has leaks at both tanks. About $200 to fix properly.

For space reasons, I'm thinking of a 24"x19" aluminum Griffin radiator with the biggest electric fan I can fit on it. About the same cost for the radiator as to fix the old one, plus extra cost to upgrade the fan from the old four blade fixed fan with no shroud.

Would that combo be sufficient for a 425 with lots of airspace around it?