Breaking in a new engine.

The idea behind breaking in an engine is nothing new. The goal is to mate the parts together so that all the meticulous work you did up to this point pays off with a long lasting, peak performing engine.

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Bearings versus Rings.

There are two big areas of concern:

1. Breaking in the cam, lifters, valve gear, and bearings.
2. Breaking in the rings.

To a degree, these goals are not compatible. The cam, bearings, and other heavily lubricated parts want a nice easy time with lots of oil to gently wear together. Rings, on the other hand, want some pressure to quickly seat the against the cylinder walls and avoid a condition known as "glazing". This is especially true for Moly rings - cast iron rings break in a lot easier.

Since sooner or later I'm planning on breaking in a new engine, I posted my thoughts on VV and did some other research, and here's what I came up with. I expect the initial break in sequence to take most of a day. Also, a partner may be helpful, there's a lot to keep track of and some things that really require more than two hands.

Note: This is *only* a break in procedure. This starts after the engine is fully assembled, you should have already selected parts, lubed the cam and lifters, all that sort of thing.

• Fill with non-Synth SL or equivalent 10W-30 (not SM "starburst") oil.
• Prime carbs. If electric pump, check for leaks now.
• Prime oil system - use a distributor shaft in a drill, and spin the oil pump thru the distributor hole. While maintaining oil pressure, turn the crank through at least two full revolutions.
• Install distributor and static time - I want the engine to fire immediately, not crank forever. Excessive cranking can wipe out the cam.
• If engine does not fire within a few cranks, stop and figure out why.
• Start engine, and in neutral, vary speed between 1800 and 2500 RPM for 30 minutes. Do not let the engine idle. Use this time to note any problems.
• Shut off engine, fix leaks or other noted issues. Change oil and filter - drain the oil while still warm, but allow the engine to cool completely. If you've done the initial cam break in on a stand, install the engine.
• Start engine, check timing, drive gently to warm up engine. Drive to break in area.
• Break rings in with a series of throttle up/throttle down runs over 15 minutes or so, start with half throttle/3000 RPM shifts and progress to full throttle/yellow line - 5200 for a stock "891" cammed Corvair engine, perhaps round down to 5000. A winding road could work, but slow down considerably for turns to keep oil in the pan.
• Avoid shock loads - it's ok to go full throttle, but have the clutch fully engaged first. Ease into the gas somewhat.
• Drive home, allow engine to cool somewhat, and change oil and filter as before.
• First 1000 miles, vary speed and load. Take care not to exceed yellow line.
• After 1000 miles, change the oil. Then drive as usual.

A final note - you should especially avoid shock loading if other parts of the driveline are new (or if you doing this on a new car, not a Corvair). Everything else would like to be treated nicely for the first thousand miles or so, especially in regard to temperature. The break in process creates additional heat, so be nice to those parts.

One comment on manufacturer break ins - the engine in a new car has been run prior to you getting it, so it doesn't need the cam part of the break in. In some cases they have been run hard on rollers, which would avoid shock loads and g-forces, but would allow the rings to seat. I believe a big part of the reason the makers recommend a gentle break in is for the rest of the driveline, not the rings.

Here's a great tip from Tim Colson:

i monitor oil pressure with my adaptabolt gauge for the first hour or so of engine running. i am looking for too much or too little pressure. years ago i ran into that trap. had a tough time adjusting valves, until i found a relief spring had been tampered with. this was on a chevy V8.

regards, tim colson