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300 break in process

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Old Sep 3, 2014 | 06:01 PM
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300 break in process

we just got done with a rebuild on the 300 in our 79 F100. I bought the royal purple break in oil from o'reilly. I put it in and the truck starts and runs good, but I would like to know the break in process to do it correctly. the only bad thing is I don't have a tachometer on this truck. would there be any other way to do this?
 
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Old Sep 3, 2014 | 06:06 PM
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Get a cheep tach and run at 1500 -2000 rpm for ten min. to break in the cam .
 
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Old Sep 3, 2014 | 06:22 PM
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A tachometer is much cheaper than a ruined brand-new engine, right?
 
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Old Sep 3, 2014 | 06:49 PM
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A Sun SuperTach III is $45 from Autozone.
 
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Old Sep 3, 2014 | 07:03 PM
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Originally Posted by HIO Silver
A Sun SuperTach III is $45 from Autozone.

Ive had 2 of the sunpro 3 tachs and ive had issues with both on different trucks. They seemed to only work when they wanted to and at times read 0 rpm on a 95 as well as a 78 pickup. My friend had one in his pulling truck and same issue. Not sure if a bad batch or not. We got them at the local autozone.
 
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Old Sep 3, 2014 | 09:25 PM
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Last break-in I did was "tachless". You want 2000+ RPM for 20+ minutes for the cam/lifters. 2000 RPM is more than a fast idle but not revved crazy high. I judged by ear and varied a bit. It worked. Getting the timing and mixture in the ball park along with a good fan in front of the radiator helps a lot in avoiding overheating. After the cam break-in, it needs some load to seat the rings. Adjust timing and mixture as needed then drive it, step on it but not continuously for a while and enjoy it.

A "known good" carb on break-in helps a lot in getting the mixture close.
 
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Old Sep 3, 2014 | 10:58 PM
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Originally Posted by fmc400
A tachometer is much cheaper than a ruined brand-new engine, right?
true story. I guess it's time to invest in a tach.
 
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Old Sep 3, 2014 | 11:30 PM
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As stated above get a tach. Break in that cam at 1500 to 2000 rpm for 15 to 20 min. After she cools down change the oil. Make sure you add some zddp as well.
 
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Old Sep 3, 2014 | 11:49 PM
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Yes, you have to use the zinc additive. Try the inline forum too.
 
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Old Sep 4, 2014 | 08:09 PM
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We bought the royal purple break in oil that has the zinc in it, will this be okay?
 
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Old Sep 5, 2014 | 08:44 AM
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Originally Posted by Dr. Dirt
We bought the royal purple break in oil that has the zinc in it, will this be okay?
As long as it brings the zddp to an acceptable ppm you should be good. From what I understand including your base oil, 2000 parts per million is a good number to be at.
 
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Old Sep 5, 2014 | 09:36 AM
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Originally Posted by Dr. Dirt
We bought the royal purple break in oil that has the zinc in it, will this be okay?
You should be fine. Some cam mfg's like you to use an oil additive for normal use. Check with them and see if you should use one. Good luck. BTW, there is an inline forum here.
 
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Old Sep 5, 2014 | 02:19 PM
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Originally Posted by F-250 restorer
You should be fine. Some cam mfg's like you to use an oil additive for normal use. Check with them and see if you should use one. Good luck. BTW, there is an inline forum here.
thank you. I'll post it in there and see what I come up with
 
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