Engine break-in temperatures

S

SuperKONR

Active member
I've got my new 200 running on my test stand and was wondering what kind of temperatures I should be seeing while parts are still wearing in. I've run it a total of probably 20 minutes so far. I just picked up an infrared thermometer to check on things. When I first ran it, the paint on the header caught fire after a few minutes but I think that was because of the crappy carburetor with vacuum leaks. I ran it today with a known good carburetor and at one point the radiator shot out a good foot and a half geyser of boiling water. I'm hoping that's because I forgot to turn the fan on. I had the cap off to bleed the air out.
On a positive note, it doesn't seem like I flattened the cam. I was pretty worried about that.
Thanks
 
Hi, you have many variables here. Is this a stock rebuild or high compression monster? High compression engies may run hot. You should have a thermostat, I would go with 180 for now. If your crappy carb and vacuum leaks made the engine run lean that will hurt, Retarded timing will make your engine run hot. How much water does your system hold? I would hope at least 1 1/2 gallons. You need to have room for expansion in the top tank and geysers scare me. I know a little trick where you drill a small hole in the moving plate part of the thermostat. This will allow the water to fill the cooling system with no air locks. This trick is from cars that are known to have hard to bleed the cooling systems. The engine should run fine all day long. Have you had trouble with other engines on your stand? Do you use an engine fan on the water pump or just a big fan in front? Or both. I hope you have good airflow and ventilation for your project. Good luck
 
B RON CO":2zkf2tvb said:
Hi, you have many variables here. Is this a stock rebuild or high compression monster? High compression engies may run hot. You should have a thermostat, I would go with 180 for now. If your crappy carb and vacuum leaks made the engine run lean that will hurt, Retarded timing will make your engine run hot. How much water does your system hold? I would hope at least 1 1/2 gallons. You need to have room for expansion in the top tank and geysers scare me. I know a little trick where you drill a small hole in the moving plate part of the thermostat. This will allow the water to fill the cooling system with no air locks. This trick is from cars that are known to have hard to bleed the cooling systems. The engine should run fine all day long. Have you had trouble with other engines on your stand? Do you use an engine fan on the water pump or just a big fan in front? Or both. I hope you have good airflow and ventilation for your project. Good luck
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It's a somewhat built engine but stock compression for now. I have a 180 thermostat in it with a 1/8" hole towards the top. That first run was definitely way lean, but I didn't run it long so nothing should've been damaged. This time I had a good carb and got the timing dialed in to 10 degrees right away. The cooling system took probably 2 gallons. I use a big portable swamp cooler that I put in front of the radiator, on high it's like highway-speed airflow. It's outside so there's plenty of ventilation. A possibly related issue is that it runs a little erratically below around 2000rpm. I can't get it to come close to an idle smoothly. It revs fine and will run pretty well above that. I'm going to mess with it today and try to make sure there are no vacuum leaks on the manifold as well as check the spark plugs.
Thanks!
 
Hi, inability to idle sounds like you still have vacuum issues. Will it at least run now on high Idle? You should be getting close. At high idle it should not overheat. A dumb question, On the thermostat, the spring is in the engine, right? The upper hose should get hot to the touch. You may have valve adjustment / lifter issues causing your poor vacuum. Good luck.
 
B RON CO":2g2wl6v5 said:
Hi, inability to idle sounds like you still have vacuum issues. Will it at least run now on high Idle? You should be getting close. At high idle it should not overheat. A dumb question, On the thermostat, the spring is in the engine, right? The upper hose should get hot to the touch. You may have valve adjustment / lifter issues causing your poor vacuum. Good luck.
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It'll run at high idle, just not very smoothly. It will cut out and die if I try and idle it below probably 1000. I was thinking maybe valve adjustment could be an issue. They are hydraulic lifters. When I put it together I adjusted them when I was priming the oil pump so they should be fairly close, but I'll check them again. Yep, the spring on the thermostat is in the head. I'll adjust the valves and check everything for vacuum leaks and see how it goes. Thank you!
 
If you have adjustable rocker arms loosen them up. The push rods should spin between your thumb and finger. If they clack a little thats OK. When you get the engine running smoothly and idled down you can make your valve adjustment with the engine running. I would run the engine and slowly tighten the rocker until the ticking stops. Too much and the engine will lose vacuum and start shaking. Good luck
 
I loosened up all the rockers about 3/8 turn and they are clattering a bit so I know they aren't too tight. It's still only pulling around 7 inches of vacuum at high idle. I can idle it down but it starts getting pretty erratic. It still takes a bit of throttle to keep it idling. The cam that I put in it said fair vacuum, so I imagine I should be getting at least 12in if it's running properly. I'm going to pick up some more carb cleaner and double check that there aren't any leaks on the manifold.
 
Hi, give more feedback, does it still run too hot? will it run on it's own? do you still shoot geysers? I hope not. Set your timing to about 8 advance and run it! You should not have a way different "break in motor". May be time to go over those rockers again, when the engine is running, check to see if you it need to loosen or tighten them by ear.
 
B RON CO":rnuw75cj said:
Hi, give more feedback, does it still run too hot? will it run on it's own? do you still shoot geysers? I hope not. Set your timing to about 8 advance and run it! You should not have a way different "break in motor". May be time to go over those rockers again, when the engine is running, check to see if you it need to loosen or tighten them by ear.
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I didn't run it very long, I just saw that it was low on vacuum and assumed that it's still lean. Still won't idle smoothly. I'll recheck the timing and run it to see if it gets hot again.
 
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