Engine Engine break-in process

[keel]

Just got my fully rebuilt 302 (bearings, rings, ect.) up and running, it runs and sounds great. It's a stock short block with a TFS1 cam and a GT40 top end. I've put about 20 miles on it so far. I've been poking around on forums a bit about the proper break-in procedure for this application but I can't seem to find a consistent answer. Everyone seems to have a different opinion about when to change oil, how it should be driven, that sort of thing. What have you guys had success with?

 

[Noobz347]

You drive it like you have some common sense for a few miles. If you used cheap break-in oil, I would change it between 50 and 100 miles just so I could get a good look at what metals have been flushed out.

Better oil? You can go a little bit longer.

The first change is not for the benefit of the oil. It's more for your benefit so you can see if anything is amiss.

Modern piston rings and bearings being what they are now... They don't need too much of a break-in period. Your rings are seated [already].


Side Note: You should not break in a new motor on synthetic or synthetic blend oil unless directed by the engine builder ( and he better have a good reason on a Windsor ).

 

[AeroCoupe]

Its a roller camshaft motor so its no like the old days of breaking in a flat tappet camshaft. Noobz nailed it with drive it like its a new motor for a bit. Check the coolant level and top off as necessary, watch the oil level as if it goes down fast the rings are not sealing (happened to me once...bad finish hone), and I use an oil with zinc and phosphorus but with the off road X-pipe. A caution for those with catalytic converters, according to Brad Penn oil high phosphorous levels can lead to catalytic converter ‘poisoning.’ However, the effects on the catalytic converter appear to be minimal during a short break-in procedure. So if you have cats then run the break in oil for a bit then dump it and the filter and go to a conventional oil.

I usually fire the motor up and bring it up to temperature and let it idle for a bit then shut it down and let it sit for a few minutes and cool off. Then I check the fluids and change oil filters and add another quart of oil. Its over kill but what's another $15 vs the thousands you have invested in the motor? I then run it for 100 or 200 miles on that oil and then change it all and then start regular oil changes or as needed if I am hammering on it at a track.

Once I have 100 to 200 miles on it I usually just let it rip. I trust the machinist / builder that I go to and this is how he has told me to break them in and so far (6 motors) zero issues. Again, roller motors and the current technology in the piston ring packs, machining, and oils help tremendously versus yesteryear.

 

[AeroCoupe]

Other thing I thought of is cylinder wash out (there are other terms for it) which is when the motor is too rich and gasoline is washing down the cylinder walls and removing the oil which causes the piston rings to not break in. So try and ensure that the motor is not running overly rich on a fresh engine start up and break in period.

 

[keel]

Is it normal to hear some valve train noise? It's not very loud, really only noticeable when I'm passing by cars and I can hear the sound reflecting off of them. The valve train components are all stock except for some 6.300" pushrods that I installed because stock length was a little too short.

 

[AeroCoupe]

With aluminum heads I tend to hear the valve train a little more. If there is any clatter vs. sounding like a sewing machine then you need to readjust the rocker arms or in your case shim them.

 

[keel]

Not really a clatter, more like a muffled sewing machine. Only around 1000-2000 rpm.

 

[AeroCoupe]

I would say normal but I have never run pedestal rockers. My Scorpion stud mount rockers make noise but they are adjusted right and on aluminum heads with aluminum upper and lower intakes so I just expect to hear them more than normal. The valve springs are also way stiffer than stock so that will add some noise with the valves snapping open and closed. If you have headers then they will add what I call header pin which is also the valves opening and closing. The more aggressive the cam the more you will hear it.

 

[keel]

Yes I should have added that I have BBK long tube headers and it seems like some of the noise is coming from those.

 

[JD1964]

Small exhaust leaks can sound like valve train noise. Normally the exhaust leaks are more pronounced when the engine is under acceleration load.

 

[Monkeybutt2000]

If you've got 20miles on it,it's time to drop the hammer. I get on a country 2 lane,start out in 2nd gear around 1500rpm and hammer it to redline,then let off the gas and let the engine slow it down. I do that several times in third gear as well. Puts a good load on the rings.