Breaking in new engine

T56elcamino

Weekend Racer
Aug 16, 2008
55
0
0
Opelousas, LA
Hey guys I just rebuilt my 388 SBC and was wondering if anyone had any recommendations for the break in period. I put some plasma moly rings in it, hypereutetic pistons, sealed power bearings. Also, if anyone has any tricks on how to get my gaskets to seal, I always have an oil leak somewhere. thanks...
 

Got Torque

Top Fueler
Oct 29, 2003
2,776
0
0
Stockholm, Sweden
After cam break-in i change the oil and then go out on a ride and focus on seating the rings.
Accelerate mildly with a locked up gear up to around 3k rpm and then let go of the gas ang engine brake down in speed. Repeat that but with increasingly more throttle and more rpm.
After i have done that a few times, maybe five times, stepping things up along the way i usually
hammer it and let it pass through the rpm range and then engine brake down to idle again. Done.

I know some guys put in their new engines and toast the rears in the bleach box and call it done.
If somebody has different ideas i'd like an update!
 

Blackwizard22

Frequent Racer
Feb 26, 2007
453
0
0
NJ
Yes if you have a flat tappet cam, follow the cam break in first.

Then take it out under load in second or 3rd gear and accelerate and decelerate for 10-15 mins to seat the rings. This makes the rings expand under the pressure of the gas and seal into the hatch pattern in the cylinder walls.

Make sure you change your oil and filter right after and initial break in will cause some stuff to end up in the oil, plus there is always shop rag lint etc in there from the build.

I always change min after break in, 500 miles, and then every 2000. I also run no pressure bypass and a 2 quart truck filter.

As for leaks, as the engine heats and cools for the first time you will have things expanding and contracting and seating which means youll probably have to tighten some things up. You should be going over the fasteners anyway after start up and checking to make sure they are in spec.

Make sure to check the valve lash after break-in as well.
 

T56elcamino

Weekend Racer
Thread starter
Aug 16, 2008
55
0
0
Opelousas, LA
thanks for your help guys, I seem to notice a good bit of smoke coming out of my pipes just at random times, and I was wondering if this is normal, I know there is going to be some until the rings fully seat but it just kinda makes me feel uneasy about it. I put about 150 miles on this engine so far but have just been driving it really easy, but not lugging the engine. I inspected the cylinders and they still had cross hatching on them. the last time I built this engine it smoked until the day I pulled it out and I put like 20,000 miles on it. I rebuilt it cause I left a spacer out on my bellhousing adapter kit for my six speed and it wore the thrust bearing out and was making a knock. I was really hard on that engine though, even before 500 miles after the build I was balls to the wall. I also read somewhere that my screw in studs in my head could have some oil seeping through and into the intake runner. Or my carb is dumping too much fuel and washing the cylinders of oil. not sure but anymore suggestions, cause I'm all ears.
 

T56elcamino

Weekend Racer
Thread starter
Aug 16, 2008
55
0
0
Opelousas, LA
almost forgot, do I accelerate rapidly or just kinda 1/4 throttle it when accelerating and decelarting?
 

Got Torque

Top Fueler
Oct 29, 2003
2,776
0
0
Stockholm, Sweden
T56elcamino said:
almost forgot, do I accelerate rapidly or just kinda 1/4 throttle it when accelerating and decelarting?

If you have 150miles on the engine i would at least half throttle it and completely lift off on decel.
 

Blackwizard22

Frequent Racer
Feb 26, 2007
453
0
0
NJ
T56elcamino said:
thanks for your help guys, I seem to notice a good bit of smoke coming out of my pipes just at random times, and I was wondering if this is normal, I know there is going to be some until the rings fully seat but it just kinda makes me feel uneasy about it. I put about 150 miles on this engine so far but have just been driving it really easy, but not lugging the engine. I inspected the cylinders and they still had cross hatching on them. the last time I built this engine it smoked until the day I pulled it out and I put like 20,000 miles on it. I rebuilt it cause I left a spacer out on my bellhousing adapter kit for my six speed and it wore the thrust bearing out and was making a knock. I was really hard on that engine though, even before 500 miles after the build I was balls to the wall. I also read somewhere that my screw in studs in my head could have some oil seeping through and into the intake runner. Or my carb is dumping too much fuel and washing the cylinders of oil. not sure but anymore suggestions, cause I'm all ears.

What color is the smoke? What does it smell like?

Did you use sealant on the head studs?
 

T56elcamino

Weekend Racer
Thread starter
Aug 16, 2008
55
0
0
Opelousas, LA
its blue smoke, smells like burnt oil. my friend gave me the heads and I asked him if he put some teflon paste or tape and he said he thinks he just put thread locker.
 

T56elcamino

Weekend Racer
Thread starter
Aug 16, 2008
55
0
0
Opelousas, LA
I don't understand what you are asking. I lubed the cylinder walls with some 10-30 penzoil and installed the piston. I didn't put any additive or anything...
 

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