engine overheating

I know this had been addressed before but I am at my wits end with this problem.  My 57 chevy truck has a rebuilt 350 with a fluidyne radiator.  The vehicle will not run cool.  It has a edelbrock performer intake w/600 carb and a mild street cam.  The system seems to be flowing and no kinks in the hoses. The cap stays pressurized. Timing is OK.  It will not stay cool. The whole system is almost new as there are very few miles on the motor, only break in miles. The only thing that I can think might be the problem is an air pocket somewhere.  I've tried several things to remedy this problem.  I'm hoping someone might shed some light on something I may have missed.  Oh yeah, the truck sits low (6" drop on a straight axle). Any help would be greatly appreciated.  

Are you running a thermostat and what is the size of the waterpump pulley? You maybe running the water too fast through the radiator and not giving time to cool.Also what fan are you running? Check to see if the fan is pulling in the right direction, especially if your running thermofans, it is easy to make a mistake and run them in the wrong direction thus sucking or pulling.  

You fail to mention several factors that could affect cooling. What type of fan are you running? Are you running a shroud? What are you using for coolant? (100% ethylene/glycol antifreeze will not effectively cool) Are you losing any coolant? What is the actual running temperature of your engine? (220 deg. is not too hot for a modern engine) Are you running any accessories off the water pump belt? (Too little belt contact with the *** pulley will result in slippage that will not squeak.) Is the radiator new or previously used? Are your heater hoses connected to a heater, or do you have a hose connected between your inlet and outlet? (This will allow too much coolant to bypass the radiator. It is better to plug heater connections than to install a "loop-back".)
I hope these suggestions will be of some help.    

I am running a thermostat that is rated at 185.  the radiator is new as well as the whole system.  The pulley size I am not sure of I will hve to measure, but the coolant is not circulating at a rapid rate.  The fan is a six blade that has a shroud around it and it pulls the air away from the rad.  Hoses are all new.  I have removed the t-stat to run to see if there is a difference or not.  No change. Drilled a 1/8" hole in t-stat to allow for any air in system. I have drained and flushed the sytem again and still no luck.  

I was reading ad. What did the 350 come out of. I had a friend who had a 350 but it was from a vette. rev. water pump. make shure you'll putting belts on right.

Also you might want to check water pump maybe bad from new. go with a high flow water pump.

Just a sug. I had a low sitting streetrod and I used a product that kept the car under 200 all the time. Might want to look into it. Evans cooling.  

The motor was a rebuilt through a local machine shop.  it has a four bolt main with 30 over pistons.  The cam is a mild street with a Edelbrock performer and a 600 carb.  The waterpump was new as well as everything else in the system. This is just maddening not to be able to solve this. In regards to a previous post I checked my pulleys and the crank is around 7" and the water pump is about 6", so I am not severely out of ratio.  If anything it should be fine for cooling.  I'm stumped.  

I had a simular problem with my small block Ford. Every time I drove, even a short distance, it overheated.Eventually I discovered the harmonic balancer was the wrong one. The timing mark was off a bunch.
Changed the timing by "eye and ear" until it ran smooth and temp dropped. Then placed a new timing mark on the balancer.  

Over the weekend I flushed the system, checked all components.  Added a 30/70 mix of coolant and added RMI-25 to inhibit future corrosion.  The system still overheats but now I wonder if the problem is air in the system.  The temp gauge reads around midway then it will bounce and start to go to the high range.  Is this an indication of air in the system somewhere?  Also, the top of the rad is hot, indicating therm is opening, and the bottom of the rad is a lot cooler.  Any suggestions?  Thanks to all who have replied.  

this might sound stupid but why not check with another rad. maybe one of your cores has a bend in it or something got in and clogged it.


I know my car sometimes the temp gauge will go over half and then drops really fast. but never had a overheating problem.

now my other car had a real heating problem I switch to that evans cooling system. but you have to change alot of stuff for that to work. trust me it works.

But in your case I would try another rad before I go nuts on anything else. Might just solve your problem.  

also how far is high range. does it go past 3/4 of the gauge. thats high if it's just past the half way point and stops sitting well thats not overheating.
lower cars run around 195 to 210 everyday and no problems if your blowing hoses then there's a problem.  

The temp swings all the way to the hot mark on the gauge.  I thought maybe the gauge was at fault, so I hooked up another to check and its readings are fairly accurate.  Its running really hot around 210-220 at idle. Changed the rad cap to be sure and still no change.  I'm going to change the thermostat again and double check its operation.  One question, should I change the t-stat to a higher temp range?  Right now its a 180.  Maybe go to a 195 high flow?  

Going to change hoses, check pump and change t-stat this weekend. Hopefully i'll solve this.  The temp guage doesn't have a numeric position on it just cold and hot, and it hits HOT to which I promptly shut it down.  One quick thought tho, would the upper rad hose pressurize if the pump or t-stat were't working?  My upper hose gets hot and rigid while it seems like the lower part of the radiator stays somewhat cool. Thanks for all your replies and help.  

No if the therm wasn't working the top hose would not press at all. Now if you can you said the temp gauge was around 210 to 220 thats normal on some eng. even if you use new stuff they run hotter.
How about running a bigger fan? Sounds like it's running ok your turning it off. Did it blow hoses at all or just runs at that temp all the time. I would hook up a normal temp gauge with numbers let it idle and see if it goes past 210-220 my temp gauge in my car goes to 250 now if yours was at 250 then i would say your overheating. 210-220 on avg day cars run that all day. changing t-stat might help i'm not shure if it's going to make a big change. Putting more air thats cooler will help alot. If your not running a electric fan get one it will make a difference. Sometimes you have to run a fan on water pump plus electric. They make them push or pull.
If you want it to run 195 call that place i told you about and do what they say it will work but I'm going to warn you it's *** But your running into *** doing what your doing now. EVANS COOLING they are in the rodding books....  

I feel like such a dork!  I rechecked my timing and distributor location and lo and behold the dist. was off by a tooth.  It gave me a false reading when I was timing it.  Nothing like a little too much advance to heat you up a bit.  I'm going to check into Evans anyway, that sounds like good insurance. Thank you all for your replies to my situation.  Hope this might help the next guy.    

Just a little follow-up, when figuring out it was a timing problem for the overheat, it was also found that my vacuum advance was frozen.  This was the primary cause of the ignition keeping things hot.  Hope this might help someone else in their search when troubleshooting.