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How to break in an engine?

990 Views 10 Replies 9 Participants Last post by  nukefission
well I am having my head rebuilt and a valve job done with a 4 layer metal HG put in. And I want to know how many mile's should I brake her in for/baby her for? And should the compresion be all the way up to normal even while braking in or lower?
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Re: how to barke in an engine?

Just drive it lightly for 1,000 miles. Try not to use cruise control, you want the engine to not stay at a constant speed. Let it see small amounts of boost from time to time. Than change your oil after the 1,000 miles.
I would do the opposite.
start it up let it run for a bit then change the oil right away. Then go out and get on it quite a bit then change the oil again. You cant change the oil enough in a fresh motor. I did this as soon as mine ran i went out and did a few 3rd ggear pulls. My compression sits at a 190 all the way across. Do a search i believe there is info everyplace on this
I personally, am not a believer in "baby the car for the first ???? miles) When I built my 2.3 last year I took it easy for a couple hundred miles I didn't baby it or beat it and seemed to work out great for me! I put 19 lbs on it within 50 miles and now I have over 4000 miles on it! I changed the oil at 100 with reg oil and went right to mobil1 at 500 miles and changed again at 3500! No booos here :p my vette came from the factory with mobil 1 and has 90 k on it now and the evos come with it from the factory too! I haven't had any ring seating issues! I run 173-175 across the board, last week! Now I run her to 7500 daily under 21 lbs and am sure she will last a long time :D
thanks for the info I have a better understanding of how I should break in my baby.
now that I have the info I just have to wait for the dam HG from slowboy :(
Most sources will say to take it easy for the first 1,000 miles. Some even say not to exceed 55 mph for the first 100-200 miles. I agree with this myself, but many have different opinions. Engines are not typically fully broke in until 10,000 miles. If you do research on almost any car, you will notice that the cars will start to run better quarter mile times around 10,000 miles than they did right off the showroom floor. Most people on here will not keep an engine the same for 10,000 miles though. ;)

Take care,

personally i dont know why there is any mention of engine break in procedures at all... there is no break in for this when you are just getting your head re-done with a new head gasket...i would say drive it just the same as you did before with no worries about a break in procedure and no nead to change oil after 100 miles becuase there should be no metal shavings from breaking in
so there's no need to break in the car with a new rebiult head, valve job. If their's not that's even better. I guess I thought any time something major got fixed/replaced on a car their's some kind of break in.
What about the other around? rebuilt bottom end, and using same head?
"Engine break in" typically refers to the rings being seated, so yes, if you have a rebuilt block with new rings, it needs to be broken in. Otherwise no, just a head rebuild doesn't require any break in.

As for the best way to break in, babying the car doesn't seat rings. What does is a lot of cylinder pressure or a lot of crankcase vacuum, or both. Translation, break in an engine by beating on it with high load at low to moderate RPM (drive up a hill), and cruise around at varying RPM (2000 for a while, 3000 for a while, etc). Or if you really want to get serious, fit a pump to the crankcase to pull a bunch of vacuum at all times.
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