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Break In not Apart


Well-Known Member
Local time
12:33 AM
Jun 17, 2021
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Mid Michigan
Whats your break in process?

Last motor I had to break in was a 350 for the (1989) 1-ton chevy van (family hauler), think I ran it at 2000 RPM for 20 min and that was it. Never did this for a motor with this much money in it (relative term), one set up for this level of performance (another relative term), and one that I really want to get right. I've always heard once it's up and running, timing is dialed in, and gauges in the green, then 2000 RPM for a certain amount of time? I've also heard that the RPM's need to vary, but never heard if that's after the 2K run in? This may be a wide open kind of question, but for a mid level performance engine, just want to get it right the first time.

Motor: 400 +.030 (405), 10.5 CP, comp cam xr292hr-10 (hyd roller), RPM Performer heads, DP4B intake
Roller doesn’t need that type of breakin, IMO. Flat tappet sis the ones that need the 20-30 min of break in. Just splashes the oil around the lobes and lets the tappet mate up to the cam. Rollers, roll. Cam is where breakin is key, always check with your manufactures.
Once the cam is broken in, you need to seat the rings.
Fill the car with your mates and take it for a long drive up some big hills. Don't let the engine bog, you have to accelerate positively up the hills.
Then on the way home give it a bit of a rev and then come off the throttle and let the compression slow the car down. Repeat that a few times too.
After 500-1000 miles change the oil and filter.
Some people baby the engine for a few thousand, some people say drive it like you stole it.
I go somewhere in between, but you're right, you should vary the rpm whichever method you use.
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