billkemper

Hello,

I recently purchased a 72 El Camino with a rebuilt 454. I believe that the motor is a 73 or 74. I have no idea who built the motor or what’s in it. It as a bit of a rough idle and I assume it has a mild cam. The thing runs very well up to about 3000rpm and then gets a little rough. It all so runs hot at the higher rpms. I can drive it around town all day and it will run cool. At freeway speeds again over 3000rpm (it has 3.73 gears) it will slowly over heat. I have changed radiator, tsat, water pump with no real improvement. Any ideas?

1fastWS6

iTrader: (3)

maybe it's running too lean or has too much timing past 3000.

Camaro396

iTrader: (14)

what are you doing as far as fans and a shroud? i know fan shrouds play a huge part in how the motor pulls air.

Richard454

You might want to check the lower radiator hose and see if it's collapsing at speed. There's supposed to be a spring in the hose to prevent this-but somebody along the way probably thought it wasn't needed!
Richard