Breaking in a Detroit

Spartan · May 06, 2017, 06:45:42 PM

How do you guys break in your Detroits? Just put new rings in my 453, and a new head.
Book just says to break it in on a dyno. Not going to do that.
Thanks
Brian

treeslayer2003 · May 06, 2017, 06:59:16 PM

don't idle it alot. i'd run it as normal. maybe some alternating unloaded rpms for the first 1/2 hour, then run her normal.

coxy · May 06, 2017, 08:24:41 PM

I always ran ours like it was in a race car (was always told to brake in a new motor like you would run it all the time) never had any issues at the end of the day dropped the oil put in new run it for a week or two and change it again then normal oil changes the longest we ever ran a 353 was 13 years it was getting so bad that every time you shut it off just for a few min you would have to give it some starting fluid

cuznguido · May 06, 2017, 09:06:42 PM

From much experience rebuilding Detroits of all sizes: Keep idle time to a minimum. Run it hard under load as much as you can. Do NOT put synthetic oil in it until you have several hours of run time on it. Shell Rotella IMO is best. Always let them idle a couple minutes before shut down will prevent cracked heads.

Spartan · May 06, 2017, 09:25:13 PM

Thanks guys

woodmaker · May 06, 2017, 10:10:14 PM

In the northeast ,the advice was "run it like you stole it"

sawguy21 · May 06, 2017, 11:11:53 PM

:D Bang your head on a sharp corner, slam your fingers in the door then run it.

Grizzly · May 06, 2017, 11:56:28 PM

Quote from: sawguy21 on May 06, 2017, 11:11:53 PM
:D slam your fingers in the door then run it.

That's what an old trucker told me when I was learning and I'll have to say that every screamer I drove treated me well.

mike_belben · May 07, 2017, 01:10:33 AM

Roll into throttle progressively. Wind up, wind down wind up wind down (like engine braking down a hill) gradualy increasing both rpm and load. No idling.

The cylinder pressure must push the rings down onto the land and outward against the bores. Only in this condition will the rings high spots be forced against the fresh peaks of the hone job and wear them down. The reason for engine braking is to let the rings come away from the walls for the metal particles to wash down into the oil. On a gasser with a throttle blade this actually creates enough vacuum to pull them back onto the piston.

If you idle it, youll scrub off all the hone peaks (like dulling a file) and there wont be any surface tooth left to machine the rings to the bore. Itll suffer from blowby and oil consumption.

All my racemotors were broken in during the first burnout. That would be best cranking compression and leakdown it would ever achieve. A street car id do in 15 minutes of building up and down in load and rpm. No steady state driving either. Roll in or roll out. Then change oil.

Ed_K · May 07, 2017, 01:35:58 PM

How many hrs do you figure till it's broke in? I rebuilt my 4-53 in 2010-11 And only have 585 hours now. It doesn't get used much.

coxy · May 07, 2017, 02:33:13 PM

when there broke down there broke in :D

mike_belben · May 07, 2017, 02:49:57 PM

It takes until the rings are lapped to the bores. Can be 30 seconds, can be never. Up to you

Spartan · May 07, 2017, 10:04:43 PM

Well it looks like tuesday will be the day the self-loader will be up there to set the engine in.

So I had to switch the governor of my old engine onto the one I am going to use.
I set the valves, injectors and rack. But there may need to be some fine tuning of the governor, and valve lash.

Do you guys wait til you've run the initial break in to do that stuff or do you warm it up then shut down and make adjustments, then fire it up again and run it?

Obviously if there is significant valve noise I will shut it down but there shouldn't be, I set it to cold lash specs.

Oh, and how do you guys prime your "dry" head and injectors with fuel? I thought about using my Mighty Vac, but don't know if that would work.

treeslayer2003 · May 07, 2017, 11:06:12 PM

if you set the cold lash, that should be good. you will have to pump the head full of fuel, the transfer pump will never do it.
start it with the valve cover off and vise grips on the control tube, just in case. you may have to run the rack again, remember those settings are very touchy, i don't feel confident setting them myself. i will do the engine work all day, i leave the settings to an expert.

treeslayer2003 · May 07, 2017, 11:08:29 PM

Brian i use the cheap hand pump most jobbers carry. plumb it up to the filter housing and pump until fuel comes out of the return. be ready, it will start "right now"

Spartan · May 07, 2017, 11:16:44 PM

Cool, thanks.

Did you have something go wrong setting up a rack before? I set it according to the book, rear injector first and so on, is it that touchy?
What's the pitfall if I may ask?

treeslayer2003 · May 07, 2017, 11:19:59 PM

i only ever had um run away on the road. 671 and 871, never a 53 but it is possible. no, mostly it will be very weak and sluggish if not set right. the best guys do not set to spec if ya get my drift......but they know what and what not to do.

Spartan · May 07, 2017, 11:37:59 PM

well my confidence just went down the toilet.

I guess I wouldn't even know who to call around here....

One thing I do have going for me is I know what it did run like when it was running good.

treeslayer2003 · May 08, 2017, 08:42:46 AM

lol, go ahead and start it with the safety vice grips and see whatcha got. we'll go from there. i know a couple tricks, i'll bet there is a couple here know a few more.

Spartan · May 08, 2017, 10:59:45 PM

Thanks Mike

Spartan · May 09, 2017, 11:37:17 PM

It's in.
However, I keep having setbacks so I did not get to try to start it today. Still have to hook a bunch of stuff up and I have to fall timber tomorrow.
Probably looking it the end of the week to start it up.

Spartan · May 15, 2017, 08:23:10 PM

She's up and running.
Took 3 tries at the governor/rack combo, but I think I have it set alright.
It will spin all 4 up against a brush pile so I'm gonna run it and see what she does. Engine seems pretty smooth.
Skidding bundles tomorrow; that will be the real test.

Thanks for the help guys.

snowstorm · May 15, 2017, 09:18:21 PM

Many yrs ago when I went to diesel tech school one of the guys was running the rack on a 671 in a 9500 gmc With that truck half the motor was in the cab. He had the doghouse out and with the valve cover off he started it and it ran away. The inside of that can was covered in oil. He did pull the emergency stop. It was his dads truck he was not impressed

Stoneyacrefarm · May 15, 2017, 09:45:07 PM

Congrats Spartan.
Good luck with it.
Keep her screaming.

coxy · May 16, 2017, 06:05:39 AM

Quote from: snowstorm on May 15, 2017, 09:18:21 PM
Many yrs ago when I went to diesel tech school one of the guys was running the rack on a 671 in a 9500 gmc With that truck half the motor was in the cab. He had the doghouse out and with the valve cover off he started it and it ran away. The inside of that can was covered in oil. He did pull the emergency stop. It was his dads truck he was not impressed

my 671 does not have a E stop and cant find a place to hook one up