Box Stock

engine break in

Run it through 3 heat cycles on the stand. Bring it up to temp then Let it cool. Do this three times and don't over rev the motor. I usually hold my at an rpm somewhere close to 4,000. I also use a carb with smaller jets.
 
Get yourself a good compression tester. Before you run the engine, test the compression. After you do what dirtracer7 did, checked the compression. Do the testing again, checked the compression again, if it hasn't gone up, you're good.
 
It all seems very difficult, we always build them, warm them up Dyno them, if it is right race it. If not tune it on the dyno, we never used any other oils than what we raced, and do not believe letting them run on the stand. There are a dozen ways to do this, unfortunately many methods fall back 50 years to a time when materials were different.

Xcell racing we find the leakdown through the spark plug hole tells us everything we need to know, I can say it is almost a 100% correct diagnostic tool when used properly.

About the only common denominator I see to our practices is an early oil change after the build, have a look at the oil, and go race.
 
The 70's are over, materials and oils are different, the days of "slow" driving or idle breakins are over. Build it with the right parts and right clearances and hammer down. With the chrome rings, you only get a short chance to seat them right. Only way to seat the rings is with heat and compression. Put your race oil in it and if you have a dyno run it there, if not, put it on the track and hammer down. Of course this is just my opinion, but it is what has worked best for me for many years now.
 
I'm sure many of you build "perfect" engines, but in reality most of the stock clones or predators are going to shed a fair amount of metal in the oil during break in. Most of it is very fine glitter that stays suspended in the oil as long as you drain it right away. I like to do a pair of no load 10 minute runs and I change the oil both times. I don't feel this is necessary if you were confident your build was done right, surgically clean, and all the parts deburred and properly clearanced. Then out to the track for a mid-rpm practice session with lots of load/rpm variance. Then I change the oil again and hammer down. The engine usually continues to put elevated amounts of metal into the oil until it doesn't, I just look at the oil and what's in it and make the call from there before going to my ~1 hour of track time oil change routine.
 
I continue the controversy, I do not feel you should be getting any appreciable amount of metal showing in your oil. The preparation and cleaning at assembly are crucial. This has been stated before and dismissed by several. The engine and it's components must be washed with hot soapy water, and dried to a point where it is white glove clean. If you are getting any material especially beyond your first oil change something is wrong.

Don't wash the engine with solvents, wash with soapy hot water dry and oil well.
 
^+1 If you take a lot of time honing and cleaning you can almost eliminate the little silver flakes in an oil change on a new one. I spent about an hour cleaning parts for my last two builds and saw a huge difference in the first two oil changes.
 
alvin l nunley said:
Get yourself a good compression tester. Before you run the engine, test the compression. After you do what dirtracer7 did, checked the compression. Do the testing again, checked the compression again, if it hasn't gone up, you're good.
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You'll have to take the side cover off or use some other method to to spin the motor fast enough in order to bypass the compression release for this to be meaningful. That's partly why many opt for a leakdown.
 
dont agree with keeping at 4000 rpm to break in i usually just lightly go up and down with throttle till i cant touch engine due to heat shut off let cool change oil and then hammer down
 
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