my son has a 40 pontiac with a 400 ,has prc radiator ,puller fan incased, ,extra volume water pump , several thermostats replaced running temp usually 230". no matter what we do can not get it to run cooler ,the motor is stock?
230 is pretty warm, If it boils over, you know you have a problem. If you want some suggestions, perhaps you could post a few pictures of the engine installation, radiator, fan setup, etc. From your description, we can't tell how big the radiator is, how the airflow might be through it, etc.
Have you checked the timing? I have a 63 389 and it runs at 180 at cruise and 200-210 at idle. Also your thermostat could be opening at the wrong temp.
The water pump uses a spacer and rubber sleeves to seal to the block....if these are not installed properly the water will bypass and it will run hot. Do you have a heater? If not you may want to connect the heater fittings together.
Def post some pictures of your set up. But also check the timing. In high school I had a 68 firebird with a 400 in it. I had done a tune up on it right after I got it as it missed like crazy. Set the timing which according to the timing light was way off. It didn't miss any more but just felt sluggish and man would it heat up. Ran at about 225 to 230 like what your seeing. Turns out the harmonic balancer had slipped a little bit and I was setting the timing way to advanced even though I thought it was reading right with the timing light. I ended up adjusting it with a vacuum gauge till I got the most vacuum I could. the engine cooled right off and ran like hell after that.
If it still overheats after you check the timing take a look at the divider plate behind the water pump to see if there is excessive clearance between the plate and the impeller. I had a 421 that liked to overheat. It turned out that the divider plate had holes rusted in it.
Remember the overheating rule of thumb. Runs hot at highway speeds - not enough radiator. Runs hot at low speed - not enough fan. When is it running hot? Yes 230 if correct is too hot. Gary
If the engine has never been apart you might have the clogged water jackets around the cylinders . I had a chevy engine that ran hot like that. I took out the freeze plugs and found very rusty sludge . I used a coat hanger a water hose in them and it cured it. The one on the r/r was the worst .
My 67 GTO 400/360 HO never ran hot. Make sure the outer ring on the harmonic balancer hasnt spun and the timing is way off. How does it run ?
As mentioned you need to pull water pump and set divider plate on pump with new gasket in place. you may have over a 1/4" from impellar to divider plate. Too much clearance will cavitate antifreeze and wont get the proper flow.. This is a result of rebuilt pumps over the years not being built to spec. Most prefer a cast impeller over a stamped one. Anyway it should be less than an 1/8" . Peen down the divider plate if excessive.
Make sure you have this plate behind the waterpump the 2 piece one is 1964 to 68 timing covers/motors...the one piece with perimeter holes is for later timing cover/motors..
No, too lean a mixture can cause overheating. The leaner the A/F mixture, the hotter the combustion.... This can even cause burnt exhaust valves or pistons.
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