What's your method for breaking in a rebuilt engine?

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Corrupt_Reverend

Corrupt_Reverend

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I should be firing my newly rebuilt engine for the first time tomorrow.

A few minutes ago, while installing the drive-shaft, I began to wonder about beark-in procedure etc.

Anybody have some tips on firing a freshly rebuilt engine for the first time?

Should I let it sit and idle for a while? How long should I wait before changing the oil? Number of miles of keeping my foot out of it?

Thanks in advance for any input.

Edit: I know to crank it without the plugs to get the oil going first.
 
1. Always bring engine to FULL operating temperature before high revs.
2. Drive the car easy for the first 10 miles or so, varying the rpm's from 2,000 - 5,000.
3. Then, start bringing the engine up to maximum rpm's and letting the engine bring the revs back down by coasting in gear.
4. Repeat several times in order to create maximum heat in the cylinders.
5. Drive around at lower RPM's for several more miles, remembering to vary the speed of the engine every couple of miles.
6. Repeat number 3, 4 and 5.
7. Park car and let the engine cool down overnight.
8. Repeat all the above 2 more times.

Your engine is now fully broken in correctly and can be driven hard from here on.
 
You didn't say if you are breaking in a flat tappet cam with this start. If so, then you must follow the cam mfr's start-up instructions.
 
I make sure the engine is pre-lubed.
Set the timing.
Pressure up the fuel system & make sure the carb has fuel.
Put a fan in front of the radiator.
Make sure it has spark.
Fill & bled the cooling system.
tools on hand for minor concerns (hose clamps)

I want it to start like it had never shut off.
Run it a varying RPM's for 20-30 minutes.

Check for leaks & recheck timing.

Then go racing.
 
a friend built a 400 based 512 stroker.
fired it up,set the timing at 34 and ran it for 15 min at 2000 rpm
took the car to the drags in Luskville and ran it hard all weekend
first pass went 10.7 in a very heavy cuda
brought it home and installed it in his street Duster...beautiful package
 
Corrupt_Reverend said:
I should be firing my newly rebuilt engine for the first time tomorrow.

A few minutes ago, while installing the drive-shaft, I began to wonder about beark-in procedure etc.

Anybody have some tips on firing a freshly rebuilt engine for the first time?

Should I let it sit and idle for a while? How long should I wait before changing the oil? Number of miles of keeping my foot out of it?

Thanks in advance for any input.

Edit: I know to crank it without the plugs to get the oil going first.
Click to expand...

The main goal here is to build up oil pressure in the engine before starting it. I don't think that the starter can crank the motor over fast enough to actually build enough oil pressure.

Take the distributor out and prime the pump directly with a hex rod and attach it to a drill. If you have an oil pressure gauge hooked up you should see the pressure build.
 
Right afer the first start, look for leaks!

I like all the above info and do that. I race a lot of my engines and try to get 100-300 street miles on them at widely varying conditions before the first rally. That mileage is a full break-in in my view.
 
ir3333 said:
a friend built a 400 based 512 stroker.
fired it up,set the timing at 34 and ran it for 15 min at 2000 rpm
took the car to the drags in Luskville and ran it hard all weekend
first pass went 10.7 in a very heavy cuda
brought it home and installed it in his street Duster...beautiful package
Click to expand...

I am with you beat the **** out of it.
 
Get the cam broke in and the drive it like you stole it.
 
I broke mine in last night. Fired it up and let it run at 2000 rpm for 20 minutes. Turned it off and let it cool down completely then ran it through another heat cycle. I'll run another heat cycle tonight and beat on it. If it doesn't fire then your timing may be off 180.

Leave the radiator cap off to allow the air to escape.
 
Yup... I built a running stand for two reasons - as a builder it gives me control over the cam break in process, which means when the customer gets it it's ready to drop in and drive... And it makes it much easier to get things like initial leaks, inner springs, and retourqing don when it's not in a chassis. But once it's in it should be driven hard - high load but not high rpms - to seat the rings. The 496 I just finished got that. It's maiden voyage was a 200 miles round trip over mountains. It's going on a chassis dyno at some point but the break in is long completed.
If you can see a strong hone pattern - chances are very good that the walls are rough, and the break in should be the old process. Nowadays the correct finish is more like a hazy mirror than a rough cross hatch.
The best way to do it is get it on a dyno. It allows for what my stand does, with the ease, but also allows for a load to be placed on it to seat the rings without being stupid.

I'll add - that link is for bikes. Bikes (especially the air cooled performance bikes) run very different tolerances than a V8. Espeically piston to wall and ring gaps. The break in for a powerful bike engine involves starting, running for a very short interval, and shutting it down to let it cool completely. Then starting it again and running a little longer, maybe loading it lightly a little, then shutting it down and cooling completely. Then running it hard and letting it cool completely. At least thats how the fast bikes I know of do it. If you started an air-cooled bike, and ran it hard without letting the pistons and rings wear in a little and cool down - chances are it would seize. See that too...lol. but maybe this guy runs his engines looser.
 
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