New motor break-in with babbit bearings

1930marie

1930marie

Senior Member
There are many threads on this subject, however, I dont remember reading how our fellow A'ers do it in a big city. I would like to hear how you go about getting those rings seated.
 
Last edited:
Don’t rev it don’t lug it and after you have a few miles on it accelerated hard for
2 or 3 seconds in second or third gear. Keep varying your speed for the first 300
To 500 miles.
 
When mine was rebuilt I was told not to go over 30 for the first 300 miles, and to vary the speed. Takes a while to do 300 miles that way
 
Exactly my point. Going up and down 20-30 mph for 300-500 miles will take me a year and how will I know the rings actually seated?
 
The first erngine I broke in easy and cartefully, not over 35 for a long time, it only lasted 3000 miles ---after fixing it with new main babbitt I "broke it in" in 2 days---on the PA turnpike, kept it to 45 till Harrisburg, then 50, would do 67 in Ohio---drove it over 60 the rest of the way, still tryinh to break it 35 years later,New iron rings "seat" quick if the cylinders are properly prepared (round, not tapered or barrel shaped), used rings take longer
 
I have rebuilt and replaced pistons on a few things now and have never had to do it twice. As for break in I wouldn't go out and rag on it. And i wouldn't be able to stand driving slow enough to lug it. But I just drive how I would normally. Lets call it driving with a little gusto.
 
1930marie said:
There are many threads on this subject, however, I dont remember reading how our fellow A'ers do it in a big city. I would like to hear how you go about getting those rings seated.
Click to expand...

If concerned about making sure that rings seat quickly and positively, use modern thin rings. My latest B took maybe 1/2 hr on a stand. No oil burning, no blow by and no smoking. You can use all other internals as you wish/have. Thin modern rings seat quickly in a properly prepared cylinder. Of course, you have to have pistons for these rings, but if starting a rebuild anyway , may as well not have such seating worries !
 
I've rebuilt several of my engines. After the first start, I let it run for about 15 minutes Then, I rev it a few times, let it warm up, and torque the head again. After I've driven it around my neighborhood for a while, torque the head one more time.
 
Babbit bearings make no difference in break in. I just gradually accelerate to about 45-50, then let off down to 25 or so and do it again 4-5 times. The deceleration sucks oil up the rings. The accelleration forces the rings against the cylinder walls. Do it a few times over a couple days and all is well. Just for fun, try tracking compression tests. Check compression initially and as you proceed. The compression will increase over a 1000 mile period, but that does not mean you cannot drive it normally after a few accellerations. It just takes time for a perfect fit, but a perfect fit is not necessary for a driver.
 
Railcarmover said:
What difference does babbit bearings make on how you break an engine in?
Click to expand...

I honestly dont know the answer to that. This entire engine replacement has been a double edged sword. I now have a new motor with more power thanks to a Snyder head. On the flip side, my car suffered paint chips and scratches that may well be the norm when installing a new motor, but hard on me. I am interested in breaking this motor in correctly and never having to pull the motor again.
 
PC/SR said:
Babbit bearings make no difference in break in. I just gradually accelerate to about 45-50, then let off down to 25 or so and do it again 4-5 times. The deceleration sucks oil up the rings. The accelleration forces the rings against the cylinder walls. Do it a few times over a couple days and all is well. Just for fun, try tracking compression tests. Check compression initially and as you proceed. The compression will increase over a 1000 mile period, but that does not mean you cannot drive it normally after a few accellerations. It just takes time for a perfect fit, but a perfect fit is not necessary for a driver.
Click to expand...

Ive been able to do 25-35 pulls in our area, but I will have traffic stacked up if I go into the heavy traffic here. Speed limits are all 45/50 and up. I think Im going to have to wait for this daylight savings to end so I can hit the road at 6:00 am with no traffic issues.
 
I have broken in a number of engines easy and raw-dogged others. Could not tell the difference.

Drive it as you normally drive just vary engine speed. No cruise control and 500 mile trips
icon7.gif


Change oil at the 100 mile mark.
 
If your bearings are poured and fitted correctly then the run in period will have no effect on them.My only break in advice is change the oil frequently,within the first two hours to remove assembly debris,then four hours,then 100 miles then 500 miles for metal slough off from rings.

Dirt and debris introduced during assembly occurs no matter how clean you work.

Drive the car as you would normally.Almost all the failures of new engines Ive seen had nothing to do with how it was broke in,if its assembled correctly it will last.
 
Congrats on a new motor "Merry Christmas to you" This sounds like a great problem to have... I'm glad the engine starts each time I push on the starter :rolleyes:
 
1930marie said:
I honestly dont know the answer to that. This entire engine replacement has been a double edged sword. I now have a new motor with more power thanks to a Snyder head. On the flip side, my car suffered paint chips and scratches that may well be the norm when installing a new motor, but hard on me. I am interested in breaking this motor in correctly and never having to pull the motor again.
Click to expand...

Don't let the chips and scratches annoy you.You're the only one who focuses them.My eyes always go to the flaws in my work,I have to condition myself not to let it ruin the enjoyment of having the car. Drive it like its the love of your life,even though the dimples on her *** could hold a days rain shes still your girl..:)
 
I just drive without any consideration for break-in. About the first 500 miles, I change the motor oil to full synthetic. After 500 miles, I change the oil once per year.
 
The man that built my engine, did a B for a friend. They got it in at 3:00am, and the car headed out on a 4000 mile trip to Colorado and beyond 2 hrs later. They did two torques before he left, and I assume one down the road. Last I knew it had 35,000 miles on it. Y the way, this was a felpro asbestosis gasket.
 
You must log in or register to reply here.
Back
Top