Breaking in a rebuilt engine

[Coldhand]

I mentioned that I had a great score on a block with brand new forged internals. I got the head back from thimage.jpge shop and the engine all back together. We are going to put it back in tomorrow. With the complete rebuild, how do you recommend I break in the motor? One hitch is that the car is not street legal but we can go to a couple huge parking areas to get it rotating. I started with adding oil and turning the engine around by hand for 10 minutes. I plan on disconnecting fuel pump power line and main coil and cranking the motor under battery power to move around the oil and build pressure. Connect it up and adjust idle and such. But then what? Is there a need for a certain RPMs for "x" amount of time?

[Hot_Wheels]

I believe there is a break in procedure on flyinmiata.com or check miataturbo.net. I know you want use regular dino oil i believe with a break in zinc additive.

[Movin]

Zink after break in oil.

[Hot_Wheels]

i know there is a whole write up on miataturbo but i cant find it!! it talked about keeping certain rpms so the rings properly break in, it was good stuff. If someone finds it please post it in here.

[Hot_Wheels]

http://www.flyinmiata.com/tech/breakin.php

Everyone has their own idea of how to break in an engine based on what their father told them, manufacturer suggestions, half-remembered lore and best guesses. Our break in procedure was developed from talking to other engine builders, piston and ring manufacturers. It works quite well in our experience.

All engines are shipped dry. Double check the oil drain plug, install a new quality oil filter and fill the engine with approximately four quarts of straight 30 wt detergent oil. We recommend a change of oil and filter after 25-50 miles, again using straight 30 wt. If you plan to switch to synthetic oil, please wait for at least 1,000 miles.
Use all new coolant lines and clamps to avoid leaks.
Mix anti-freeze and water at the minimum concentration to get the freeze protection that you require. Water transfers heat much better than anti-freeze. Not a bad idea to check or replace the radiator cap while you’re at it, as most of the ones we test fail a pressure test miserably. Jacking the nose of the car up while filling with coolant ensures that the fill point is the high point of the system.
Make sure you have all your ground wires hooked up! Missing grounds can make smoke come out of expensive places.
Have your timing light already hooked up before starting the engine and have an assistant watch for leaks while you start the engine for the first time. We pack the oil pump with engine lube, so oil pressure should come up very quickly. Start the car, watch for oil pressure while your assistant looks for leaks of any kind. Fuel leaks can be especially unpleasant.
Once you have verified oil pressure and no leaks (or fixed any leaks), set your ignition timing while the car is warming up.
Do not let the car sit and idle for a long time. Once you’ve got timing set, no leaks and everything sounds and looks good, take the car out on the road.
Keep in mind that there really shouldn’t be any metal to metal contact happening within your engine, other than the rings to the cylinder walls. The rings are the ONLY things we are interested in breaking in or seating. What seats rings is cylinder pressure. Rings and pistons are designed so that cylinder pressure sneaks behind the compression rings and forces them out against the newly honed cylinder wall. Why do I mention this? Because I want you to take your warmed up car out on the road, find a nice straight stretch and do a couple of heavy throttle runs in third or fourth gear from about 2500-5500 rpm. Each time you hit 5500-6000 rpm, snap your foot off the gas and let the car coast down to 2500 rpm while in gear, to pull high vacuum in the cylinders. Repeat this step about five times and you should have a nicely mated set of rings and cylinders. NOTE: When I say “heavy throttle”, I am referring to a normally aspirated engine. For a turbo or supercharged car, modulate the throttle to achieve about zero on your boost gauge, rather than full throttle. This would be roughly equivalent to full throttle in a normally aspirated car.
Take it home, recheck for leaks, make sure fans work, etc and then change the oil.
Once you have done the ring seating, try to control yourself (or at least your right foot) for a few hundred miles, no full throttle, try to vary rpm on the highway and no revving to the limiter.
That’s it! Have fun!

http://www.miataturbo.net/diy-turbo-discussion-14/breaking-engine-fluids-anyone-71549/

[Coldhand]

That is a very nice write up with a good explanation of what is being broke in and why. Thank you Hot_Wheels.
I noticed no mention of Zinc. That must be a lubricant for the setting of the rings?

[Movin]

The write is pretty much industry standard. Zinc is a oil ingredient that like lead can leave behind trace amounts of metal if oil is burned. Lead was removed from fuel and with modern engines zinc is not needed in oil. Engines with high metal on metal loading need zinc to prevent the two surfaces from wearing excessively. A little wear is allowed for break in then zinc is used to prevent abnormal wear. Engines with this type of stress are typified by the high horsepower v8 chevy's of the 70's. The engines of this design are well known for oil quality and camshaft - lifter failure problems.

[jason_]

Jesus, turned by hand to pump oil?

Pull the plugs, kill the coil, and use the starter...

Whirl it for a 1/2 min until the lifters pump at that...

I never worry about overheating the starter, no plugs turns too easy.

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[jason_]

Can't edit post.

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[Zanzer]

Good find Hot Wheels. People are always asking me about how to break in a new engine, so that article should help answer a lot of questions.



I do basically the same things as listed in the writeup with only a few subtle differences.

- I Pack the oil pumps with Lubriplate. This is also good if you plan on letting the engine sit for a while before installing since it won't drain out of the pump

- I Pull the coil wire and spin the engine with the starter to build oil pressure before initial startup. If it's an expensive engine I install a manual gauge to verify pressure before the engine gets fired.

- I use a straight 30wt non-detergent ($2/qt at Walmart) for the first couple of hundred miles and then drain it, replace filer, and fill with conventional oil. After 1500 miles I then swap it to synthetic. Note: On my next engine I'll try the "run for 20 minutes and drain" and report any differences I see compared to running longer. Note: The use of ND oil is personal preference for me. There was a time when it was hard to find and I broke in many engines with conventional straight 30wt, either way works fine.

- Note: When installing a new cam I run the engine at 2000 rpm for 20 minutes to break in the new cam.

- I use a long stretch of road with a couple of long, but not steep grades. I get the car up to 70ish and then at the top of one of these hills I let off the gas and allow the car to cost down to around 20. I repeat this 5 or 6 times. If I installed chrome rings I will sometimes repeat this process a few more times since they are harder and can be a little more difficult to seat. Note: I usually perform this procedure late at night when there is less traffic on the road to worry about getting in the way.

- After 3000 miles and the switch to preferred oil type I consider the engine broken in and drive normally.


This is the procedure (with some personal research added) taught to me by my Father, a lifelong mechanic, and it's how I've broken in all of my engines for the last 25 years. We build everything from daily drivers to off road trucks to drag cars and it's always worked well for all of them.

[blkfordsedan]

I pretty much do the exact same as Zanzer. If I install a new flat tappet cam, I always run it for 15-20 minutes at a sustained 2500 RPM at start up to break the cam in. I also use non-synthetic, but I add a bottle of Redline engine "break in" lube.