# What's the deal with engine break-in?



## DukeB-120th (Oct 19, 2009)

Could someone explain to me what's going on with an engine when you first turn it on and break it in? What's with the heat that is so bad for headers, especially coated ones? Would this also apply to a block that has been to the machine shop, or only zero-mile blocks? How long does this excessively hot period last?

:confused


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## freethinker (Nov 14, 2009)

DukeB-120th said:


> Could someone explain to me what's going on with an engine when you first turn it on and break it in? What's with the heat that is so bad for headers, especially coated ones? Would this also apply to a block that has been to the machine shop, or only zero-mile blocks? How long does this excessively hot period last?
> 
> :confused


engine breakin is a holdover practice from the old days. it had to do with seating the rings. with modern technology it isnt really necessary but it cant hurt.


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## Eric Animal (Oct 28, 2007)

Also a new engine MAY run a little hot until the timing is tweaked,carb(s) adjusted and everything is "run in".......E


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## pontiac (Mar 6, 2011)

engine break in is still critical on a rebuild, not so much on a factory crate where there is a warranty.


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## AlaGreyGoat (Jul 6, 2006)

On a rebuilt engine, there are areas the have to "wear in". The rings and any tight fit will produce more friction and heat. This should wear in about 200-300 miles. As far as the headers, the heat burns off any oil and residue from them on start up. The heat is usually the same as it was, but the smoke makes them look hotter.

Larry


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## DukeB-120th (Oct 19, 2009)

Ok, so the excess heat comes from the "burn in" extra friction and such. Can we reach a consensus about which engines have to be broken in?:confused

Thanks all!


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## freethinker (Nov 14, 2009)

pontiac said:


> engine break in is still critical on a rebuild, not so much on a factory crate where there is a warranty.


you think? i built circle track engines for 15 years. we put them directly from the engine stand to the race car turning 7000 rpm without any breakin.


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## Rukee (Feb 8, 2007)

The break-in is more for the cam then the rings.
Running the engine at 2000+ rpms for several minutes breaks the cam in, and overheats the headers a bit.
After cam break in you want to make some hard runs under load. Accelerating hard seats the rings, and when you back off the throttle hard and let it engine brake that sucks oil up to the rings to help lubricate them. When I rebuild an engine I make many WOT passes to make sure it's healthy. I know for sure the customer is going to do this as soon as he's away from the shop, so I need to make sure it's going to handle it.


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## Eric Animal (Oct 28, 2007)

There has always been much debate on "break in" methods, and necessity, some say YES, others NO. Even owners manuals have directions for driving the first few hundred miles. There is the 2000 RPM for 20 minute rule ( for hydraulic lifters). There is the 'put it in the car and drive it like you normally would' theory. The moral of the story is: "When in doubt, break it in." How depends on what your engine is built for, and what it is built of.....:cheers


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## Eric Animal (Oct 28, 2007)

Now for the WISE AZZ ANSWER : You're an AeroSpace Engineer, YOU tell US!!!!!!!!!:rofl::lol::cheers Eric


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## 66tempestGT (Nov 28, 2009)

freethinker said:


> you think? i built circle track engines for 15 years. we put them directly from the engine stand to the race car turning 7000 rpm without any breakin.


:cheers


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## AlaGreyGoat (Jul 6, 2006)

freethinker said:


> you think? i built circle track engines for 15 years. we put them directly from the engine stand to the race car turning 7000 rpm without any breakin.


How many miles do you get out of it before it needs a rebuild?

Larry


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## geeteeohguy (Feb 2, 2008)

I have always broken them in as follows: 2000 rpm for 20-25 minutes to break in the cam. Drain oil. New oil and filter. Drive at varied speeds with no extended constant speed cruising for 500 miles. Drain oil. New oil and filter. Drive at varied speeds and a bit more aggressively, but no WOT until about 1000 miles. New oil and filter at 1500 miles and good to go. I overhauled the 389 in my '65 over 30 years ago (it has only about 50k miles on it) and it still runs as good as ever and does not use oil. I overhauled the 400 in my '67 23 years ago (it now has 77,000 miles on that overhaul) and it doesn't burn oil and runs excellent. It used to leak oil out of the rear main, but I fixed that a few months ago. When I had the pan off, I checked the bearings, and they looked like new. Extended break-in's may not be necessary, but with my time and money at stake, that's how I do it, and it's always worked for me.


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## DukeB-120th (Oct 19, 2009)

Thanks for the input, all...

And Eric, you wizeazz Animal, you! I may be an aerospace engineer, but they don't have any Pontiacs in our machine shop at work!!!!!!!!!!!!!


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## Eric Animal (Oct 28, 2007)

I couldn't help it!:rofl: E


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## jetstang (Nov 5, 2008)

I agree, newer engines don't need it as much with roller cams. I talked to the Lunati rep at the Hot rod reunion and he said the manufacturers went to roller cams to get away from warranty work for cam failure, and all things equal a roller cam is only worth a couple HP over a hydraulic cam, but then you throw in faster ramps and it's a dif story.
My money and time, I break them in. Race motors are temporary, like racing oil. Race oils don't have detergent in them because they figure there not staying together that long to get dirty.
New factory crate motors are clearanced to run out of the box without break in, for warranty reasons.


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