The Stovebolt Site Forums The Shop Area Engine Shop Breaking in fully rebuilt 235

After blowing my original 216 in June, a replacement (but used) 235 a month later, which was a dud, and I've now finally got a fully rebuilt 235 in my 1950 3600. While I know that the 235 is a better engine for daily driving than the 216, I'm still not sure how fast is too fast, especially during the breakin period (500 miles? 1000 miles?). I don't have a tach, still have the original gear set-up (3.11:1, I think) so I'm really just relying on the speedometer. Would hate to overtax this thing and blow a third engine.

Any advice would be appreciated....

Thanks,

Jon Munk
Bee, NE

You probably have a 4:11 or 4:56 gear ratio. 50-60 mph is about tops. There are a lot of theories & opinions on break in. I just don,t torture it for the first 500-1000 miles. Avoid long hard pulls, backing out of the accelerator occasionly to suck oil into the upper rings & valve guides.

Jon,

You will get alot of opinions on engine break in, but here is what has worked for me.

I have a rebuilt GMC 228 engine. During the first 50 miles or so I ran the engine around town, up and down hills ect. I worked the engine through all the gears and make sure your oil pressure stays up. Then I changed the oil. The next couple of runs I repeated the same driving and then added some straight high way runs. After about 250 miles I changed the oil again. Other than that, I tried not to rev the engine to hard, or "lug" engine.

Now that the engine has 1300 miles on it anything is fair game and It runs super smooth at any speed.

Don't forget to stay on top of your valve adjustments. Also the timing might need some re-checking after the first 1000 miles or so.

Good luck and keep us posted.

Do you know if it has chrome, molly or cast rings..???? Chrome and Molly rings ya shouldnt baby or they wont seat sometimes... Pull them hard to seat.... any engine i rebuild i accelerate hard 10 times to about 70, for that old truck id say to about 50 or 60..and let it coast back down... then hard again.. that will seat rings... as for the other parts... there isnt any breaking in of bearings,,, the only other thing is a cam and cam bearings... the old drive it easy thing was typically for new cars or trucks and breaking in more than the engine... in other words letting all the gears wear in evenly rather than hard pulling and possibly scoring a gear... anyway thats what ive been told...and for seatin those rings...that will work good and wont hurt a thing... you can even put new chrome rings in an old cylinder without even breaking the glaze... and they will seat and that slick cylinder wont wear out the new rings breaking in or seating...it will use some oil and smoke for those first few runs outta the ten,,,but wont after that...... Thats why with a diesel rebuild its best to run it on a dyno pullin full power full load to seat rings.....Im sure we might get some arguments here... but to each their own...hehehe...

Thanks for the info. I'll let you know how it goes...so far, so good. I suppose if I make it to 1,000 miles I'll have less to worry about.

Thanks again, you guys.

Jon

You don`t want any "wear in" on any bearings because that would ruin them.

The only things that have to be "run in"are:

1. New cam and lifters
2. rings

Use plenty of cam lube on cam and lifters.
Use a running in oil (I like the Penrite)

IMPORTANT!

Prime the engine with a drill till you get oil pressure

make sure it gets enough air to cool (big fan)

when you start te engine the first time let her run with continous 2000 rpm for 20 minutes in the drive way, that will break in the cam.

We had ruined cams and lifters from guys that don´t did it that way.

Then turn her off and drain the oil with a fine filter. Check the filter for any metall. Slush is normal. Change the oil filter also because it is full with slush now.

Having strong Neodyme magnets in the oil pan and on the oil filter is a good idea anyways. (I got them in the pan and you will be shocked if you see how much metal they collect)

Fill in 30 SAE oilor whatever you prefer and your done.

To seat standard rings accellerate her hard about 20 times and then let the pedal go to allow oil sucked up to rings. Don`t torture the engine. Go faster every time (20-25-30-35-40 and so on).

Molly or Chrome Rings seat slower and need a more harsh treatment.

That`s about all you can do in the moment.

Thr rings will continue to seat better and better over the next 3000 miles by them self.

All this may sound a bit over the top, but I´m german ... ah you know the deal

Good Luck! Frank

Break it in like you will drive it later, If you baby it when you drive break it in that way. If you drive like a bat out of #$%@ break it in that way. every motor that I have build I have drove it as hard as could after breaking in the cam. have not had any trouble out of any of the engines. The six that I build has been running for about 19 years. 19 hard years 5400 rpm burn outs for 15 to 20 mintues and been wide open for miles. Had a engine builder tell me to break it in like you are going to drive it also.

Super250six

i was told that when a motor is fresh that you want to baby it i just rebuilt the 350 in my 70 chevy (was rebuilt 10,000 miles ago or so) but i wanted to go over it anyway well i did all new bearings and all that good stuff kept the cam and lifters and put in new piston rings the rings i got were speed pro and had plasma moly coating on them i think and from what you guys have been saying from the parts i put in all i have to break in is the rings and was wondering how i would break them in and its it harder to break drive a motor if its a manual? cause i made my truck a 4 spd, would like to know bout breakin them rings in

Nate

I've always heard that you break it in the same way you'll drive it later.

The owners manual for the '52 Dodge says not to exceed 35MPH during the first 500 miles.

There are all sorts of views on the subject.. but my personal view is get on it.. but stay within the operational limits of the engine.