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Joined: Jul 2002
Posts: 17
Grease Monkey
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OP
Grease Monkey
Joined: Jul 2002
Posts: 17 |
What's the best way to break in a new engine?
Just installed a 261 cubic inch engine in a 1939 Chevy Master Deluxe. It seems to be running hot sitting in the driveway. I replaced a thermostat and installed a overflow bottle, but it still running hot. I ran it for about 20 minutes. I have some wiring to finish changing over from 6 volt to a 12 volt, and I thought I would try and take it out on the road. The original 216 cubic inch engine I removed, never seemed to overheat. Any suggestions?????
Still Driven a CHEVY
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Joined: Jan 2002
Posts: 30,701 Likes: 141
ChatMaster - 25,000
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ChatMaster - 25,000
Joined: Jan 2002
Posts: 30,701 Likes: 141 |
Take it out and drive it and see what happens.Did you keep the stock 1939 radiator core?..may be a little "light" for a 261.Will do better after break-in and at road speeds.Should be driven at 40 to 50 MPH, not holding any one steady speed....giving it about 10 mile trips at a ime for the first 50 miles.
Gene Schneider
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Joined: Jul 2002
Posts: 17
Grease Monkey
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OP
Grease Monkey
Joined: Jul 2002
Posts: 17 |
I installed a 13lb.cap on the radiator with a overflow bottle which I believe to be a 1939 radiator. I was told that old timers removed the bottom hose and stuck a rag inside.Then filled the radiator, pulled the rag and watched how the water comes out. If water runs good no need to clean or recore. I hope driving it on the highway does the trick, which I also thought was the best way. Thanks for the help.
Still Driven a CHEVY
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Joined: Jan 2002
Posts: 30,701 Likes: 141
ChatMaster - 25,000
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ChatMaster - 25,000
Joined: Jan 2002
Posts: 30,701 Likes: 141 |
A pressure cap will not work on a 1939 radiator.There is not solid seat on the bottom of the upper filler for the lower part of the pressure cap to seal....One side of the lower flange is cut off.
Gene Schneider
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Joined: Feb 2002
Posts: 1,178
ChatMaster - 1,000
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ChatMaster - 1,000
Joined: Feb 2002
Posts: 1,178 |
If you are going to run it in the driveway why not add a little air flow in the form of a large fan directed at the radiator. It should help.
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Joined: Jul 2002
Posts: 17
Grease Monkey
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OP
Grease Monkey
Joined: Jul 2002
Posts: 17 |
More information concerning my radiator. Lower flange of filler is not cut off. It's squared off on two sides,but still has a complete lip around. Maybe from another year. Also had car out on road for about twelve miles with themostat removed. Car ran perfect running at about halfway between 100 and 180. Antifreeze goes into overflow bottle while running and returns to radiator after cooling so its working like it should. Maybe after breaking engine in a little I'll reinstall themostat. Enjoying driving it again after two years work.
Still Driven a CHEVY
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Joined: Apr 2002
Posts: 28
Grease Monkey
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Grease Monkey
Joined: Apr 2002
Posts: 28 |
If the 39 needs some cooling help during break in just run the heater.
the thermostat is important as it creates some positive pressure in the block which prevents steam pockets in the back of the head. Keep water circulating thru the heater as that acts like a bypass around the thermostat during warm up to keep coolant moving. A 160 t'stat should be enough.
If you used a 235 head did you drill steam holes in it between cylinders? If its an "848" head from 56-62 235 it has small combustion chambers that bump up compression to slightly over 9:1 when mated to the larger bore of the 261. You will be impressed with the snappy performance.
Bob ADler
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Joined: Apr 2002
Posts: 17
Grease Monkey
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Grease Monkey
Joined: Apr 2002
Posts: 17 |
An engine with the timing not advanced enough will run hot.
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Joined: May 2002
Posts: 6,149 Likes: 42
ChatMaster - 6,000
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ChatMaster - 6,000
Joined: May 2002
Posts: 6,149 Likes: 42 |
And over advanced will run hot also, extreme over advance will cause detonation destroying pistons.
Tony
1938 1/2 ton Hope to drive it before I retire
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