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Old 01-08-2008, 03:25 PM
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Rebuilt Chev 350 Break in procedure

I'm taking advise and doing research on a proper breakin for my rebuilt sb chevy.
I have new bearings, it's been balanced, new pistons, new rings. I've gathered that on the first start up let warm up to operating temp with out any throttle. Then let cool completely, do this several times. But I've also read that some throttle is good to help seat the rings properly but not to much. Any wicked engine builders have any input for me it would be appreciated.

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Old 01-08-2008, 03:36 PM
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If this is a flat tappet cam make sure you have oil that will prevent it from going flat, as oils now dont have the additives needed. Next, break in with a flat tappet cam requires it be brought up to 1800 rpm then after several minutes moved up slowly to 2300 rpm, then vice versa. If you let a new flat tappet cam idle, kiss it goodbye. If its a roller cam you really don't have to do anything, driving it then doing a few down shifts will break in the rings.
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Old 01-08-2008, 03:41 PM
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Rebuilt Chev 350 Break in procedure

you ever seen them dyno one that is new ?
well they warm it
they time it
they rev it .
they open it up till shes screaming let me go .
they don't take it out for a drive and run it up and then back off under load to seat the rings .
i give mine what it will see in its future
wide open ,tire scorching ,pleasure
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Old 01-08-2008, 08:00 PM
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Re: 350 Break in

With the engine fully installed double check Everything as being ready to go.
It helps to have someone to assist as it's easier. Make sure all fluids are topped off. Fill the radiator up to the top but leave the cap off. Have some antifreeze ready at hand as the antifreeze in the radiator and engine block will go down as the trapped air in the system will purge as the engine warms up. When you know that you're ready you need to prime the oil pump with an external priming tool, you can find these at Summit and others. With the distributor out you will be turning the oil pump with a drill to prime the pump.
Watch the oil pressure gauge to confirm that the pressure has come up.
Reinstall the distributor. (This can be done on the stand before you install the engine, watch for oil flow at the rocker arms)

Prime the carb if it's carburated. Have your friend start the engine and bring it up to 1800 to 2500 RPM and vari it between these for a few minutes and let it warm up, watch the radiator fluid level, add as needed, cap it off when you think it's full. Don't let the engine idle! for twenty minutes.

Flat tappet cams are lubricated by the splash from the crankshaft below. This is why the need for the 1800 to 2500 RPM, to splash the cam with oil from the crank. This same splash also lubricates the cylinders and rings.

I pesonally overfill the engine with 2 extra quarts of oil to increase the splash effect to the cam. (dont drive around this way).

After twenty minutes shut it down and resist the urge to drive it. Let it cool overnight and then check everything out again for leaks and for loose bolts as it will tend to loosen bolts the first time it's brought up to temp and cooled.

Change the oil and refill to normal. Drive it normally for 500 miles to fully seat the rings, change the oil again as the engine will be "shedding metal" as the parts wear in and then have fun!
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Old 01-11-2008, 02:35 AM
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engine break in>

I agree with most of what was said, However I have a difference of opinion on using antifreeze during the break in procedure. Use straight water. I assure you that if you encounter a leak it's much easier to clean up the water than having antifreeze spraying all over. Also straight H20 will quickly seal up any improperly seated freeze plugs or fittings, where as antifreeze will seep around threats and sealant. After initial break in and confimed that there are no cooling system leaks, drain the water and refill with antifreeze. I have found this to very effective and easy to keep from making a huge mess in the engine compartment should there be a leak. One other item. I always use straight 30 wt oil with zinc phosphates like Shell Rotella T brand or Chevron Delo 400. This type of oil is designed for diesel engines and has very high anti wear additives. This aids in anti scuff of piston skirts, bearings and cam lobes. It does not hurt anything in a gas engine when used for break in procedures. After break in, I drain the oil and use what whatever, castrol, valvoline ETC.
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Old 01-11-2008, 08:32 AM
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My procedure is a combination of all of those,

You didn't mention a cam changebut if there is one follow the manufacturers recommendations,

Fire the engine, set the lifters, get it timed, check for leaks (inside and out),

Run it for 20 minutes to break in Cam and wear in most parts (use a non detergeant 30 weight oil)

Let the engine cool,

This next part is excessive but has never failed me.

Let the Engine cool, start it and run for 5-10 minutes at 1000-1500 rpm (depending on application) just enough to not load up on fuel. Make sure it has reached full operating temps, Shut it off and let it cool. Repeat 4 more times. After that you can change the oil and pretty much do whatever you want.

I don't go with synthetics until I am 100% positive the engine has worn in properly. Maybe 2k to 3k miles
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