I'm running a 350 bored .60 over with a Holley 650, an Edelbrock Performer RPM, and an HEI in my 47 Plymouth coupe with a 350TH and a Ford 9" I know that the timing is not 100% correct because it still stumbles when I stab it hard off the line. But my real concern is that when I had my radiator neck replaced (on my stock 47 Plymouth radiator) the shop changed it from an open system to a sealed system and he told me to use a 7lb cap. I did so and after my first shake down run today it got up to around 200 degrees and puked all over my garage when I got home! I filled the rad all the way up before I left and I know when I did that before the swap it would spill a little. I don't have a catch can on it right now and maybe I'll be needing one with a sealed system? This same car with a 283 the same fan (flex fan which I hate), same radiator minus the sealed system, ran around 180 tops. I also pulled the thermostat because I'm not using a heater right now. So whats my problem? Is this more than just timing? I'm sure I'm leaving something out, or missing something stupid!
200 is not overheating. Put your thermostat back in, and put an overflow tank on. Fix your timing issues, and test to see if your fan is rotating in the correct direction (pulling air through your radiator).
Yeah I should have been more clear...Why did I puke water, not over heat...I never thought about the fan, what I do know it that it went back on the same way it came out but I will def test it! Just out of curiosity can some one tell me why the thermostat needs to be in? Does it need to slow down the water? Oh and Pushrod...I have the same problem...can't answer that either! Thanks alot guys!
Thermo restricts the flow and lets the radiator cool the water more as it slows down the flow thru the rad. Put it back in and try it again.
This statement is folk lore. You want the coolant to flow as fast as possible. Thermostats are for warming the engine and not cooling the radiator. I see this dumb statement on every over heating problem. Heat travels from high temperature to low temperature. I the water is warmer in the engine the heat will not transfer as fast to the coolant because it is warm.
I am sure you had the radiator cleaned when it was getting a new neck. I would fix the easy stuff first. Timing and overflow tank would be the first things to fix. It could be running lean because of the stumble when you stomp on the accelerator. Lean will heat the engine.
Modern engines have coolant recovery tanks on them also known as puke tanks. When the coolant expands it flows into the tank. When it cools back down in the garage a vacuum is formed and it sucks the coolant back into the radiator. You never see this happening on a modern engine until a leak appears and the vacuum is broken so that it cannot recover the coolant. 200 is not overheating by modern standards. Does it puke coolant every time or just the initial time that it is filled up? If it keeps puking every time them you have a problem. If the level maintains after the initial expansion then you probably do not have a problem.
Open up the flood gates! this is a very debated topic. some say it cools better some say it doesnt. in my experience, the faster the water the better
The system sounds like it is working correctly! You have a closed system cap but not a closed system? Get a recovery tank on it so it can work properly. Of course it spilled out. It is supposed to expand into the recovery tank, and then on cooling be drawn back in. That helps purge all the air from the cooling system and insures that the radiator is always full. Make sure that the hose from the radiator to the recovery tank either attaches to the bottom of the tank or the hose goes into the tank to the bottom, so that the coolant can be drawn back in.
All very good suggestions in this thread. It's not uncommon for engines to run a little warm on the initial shakedown run because you're still working out the little bugs. Ignition timing is very important, along with the correct style fan and recovery tank. Having a fan shroud helps greatly, also. I have the feeling that once you get the timing dialed in and ensure that you don't have any trapped air in the cooling system, you'll be OK. Years ago, a buddy had cooling problems on a small block that he was pulling his hair out trying to resolve. It wound up being the wrong water pump. The later serpentine belt systems utilize a water pump that spins in the opposite direction than the old v-belt style pumps.
10 or 12 lb cap? The puke tank is not supposed to be full. if it filled all the way up, even with a high pressure cap, it will overflow. tank should have only about 2" of maybe 8" fluid when sitting cold.
Because your engine made more heat than your radiator got rid of, of course!! Sorry took a big pile of smart ass pills today Keith
Why did the radiator shop recommend a 7# cap? A good healthy cooling system usually has a 12#-16# cap to keep the boiling point down. I've only used 7# caps on weak radiator cores to keep the pressure off them. Also, I think if the coolant travels too fast it won't have enough time to absorb the engine heat.
Don't go with too high of a pressure cap-your radiator probably isn"t built to take higher pressures, and will rupture. Stick with the 7 pounder and get the timing and fan/shroud issues fixed.
I really have to disagree. I don't know the science behind it but I have seen the proof on two different cars. On one car I used a thermostat on the other car just a large washer to restrict flow, but in both cases my temp came down. I also know we use very large radiators to cool process water at my plant and we do have to control the flow to maximize cooling.
Not to mention the millions of dollars spent researching this by automakers, engine builders, radiator companies, thermal engineers, etc... It is an integral component on a street-driven vehicle.
1. The thermostat is designed to quickly get the engine to operating temperature, then allow coolant flow to maintain that temperature. Hotter temps make for more efficient burning of fuel, but are not necessary. 2. Not running a thermostat is not dumb, but it is not smart either. It will take longer for your engine to reach operating temperature and it will take longer for your engine to operate as it was tuned to. You are just making your life more difficult if you take the thermostat out on a street driven vehicle. 3. Your cooling system puked from, most likely, one or both reasons. Too much coolant in the system without a place to go (no overflow tank) and/or higher than normal operating temperatures. What to check: 1. What temp thermostat did they install? If they installed a higher rated thermostat and you don't want the engine to get that hot, install a cooler one. 2. Install a way for your radiator to catch overflow and pick it back up when the engine cools off. ie: a puke can. 3. Ensure your radiator is flowing properly. You should easily see high coolant flow with the cap off as the engine warms up and the thermostat opens.
:This answered my next question about setting up the over flow tank! Thanks! :Thats what I love about this place...Next topic PCV valves
Thats the reason for the 7lb cap. He's an old school guy and I trust him...He's of the same vintage as the radiator!
Use a thermostat. It keeps the engine temperature constant, besides faster warmup. Check your AF ratio to see if its ok. Lean will make you run hot. Also, get your timing right. Butch
The pressure of the cap has nothing to do with how hot an engine runs. I've run a couple of SBCs with original non-pressurized systems on original to the car radiators. There is no advantage of running a higher than necessary pressure cap. The only reason that they came up with a pressurized cap is to prevent the coolant from boiling on the rare occasion that it got above 212 degrees when stuck in traffic to prevent any boiling. High pressure systems are a result of pollution control to try and run higher temps than we used to run to reduce the pollutants and not a cooling reason at all. My first 34 P/U and my old 36 sedan ran perfectly well with the factory cap on the factory radiator with no modifications at all. Going with a higher pressure cap can cause the radiator to balloon because the radiator was never designed to hold those pressures. We are talking about a 47 Plymouth radiator and not a 2012 Walker clone.
So the factories and their engineers did testing on their cars back in the era we are speaking of. They ALL determined that 180* was the place to be. One of the reasons that is important is that the cylinder walls like to be that temp. This keeps them at the right size (thermal expansion) keeps the pistons at the right temp (heat transfer thru the ring contact) and keeps the lube oil at the right temp to prevent wear as much as possible. Then the circulating oil that's returned to the sump gets to be a nice temp also by flowing over all that iron that is at a nice 180*. Why do people want to fuck around with proven sucess and reinvent the wheel? This isn't aimed at the OP, he just needs to run a t-stat and keep the water an inch or two low in the header tank for expansion. Remember when they called them expansion tanks? Or put a catch can on there and recirculate the overflow. Like Tommy says. I can tell you that running the overflow tank will help cool it a little better because eliminating the air in the header tank will help the coolant from getting air bubbles from the air space above the water mixed in with the water going thru the system. Frank
wow gas pumer...great info! all makes sense to me! I'll get/make a puke tank today, set it up and add a little fluid back in and rock out to see how she does... After I re-set the timing! Thanks guys!
Could not have said it better. I see so much stuff roll through my shop where people re-engineer stuff that fails. Yes there are things that were known problems from the factory but most of the time reinventing the wheel often leads to a not so round result. I often wonder why a guy in his garage thinks he is smarter than a group of engineers with endless amounts of money for R&D.
Lots of great advise here for you n847. Yes, you should definetly run a thermostat. I use the higher quality 180 degree Stant thermostat in my SBC which you can get at any Napa. (not affilated in any way...just had a lot of luck with Stant so that's what I stick with!) Also..when you add your puke tank...or "catch can" do the following: 1) The tube should go into the catch can about 3/4 down inside the can 2) Pour a little coolant into the catch can as well so atleast the bottom of your tube is in coolant. This is how I did mine on my SBC and all seems to work well. Good luck
The Jalopy Journal
