Break in procedure

[79K15 HIghSierra]

Finishing putting together my newly rebuild 350 for my ‘79 K15. Hopefully installing it this weekend. Noob question but it’s better to ask than to not!
Proper break in process? I’m talking from first start. I know to prime the oil pump etc, but as far as breaking in the cam etc, what’s the process there, First drive around the block and stuff. Thanks so much for any help!

 

[Customblue]

Roller or flat tappet camshaft?

 

[79K15 HIghSierra]

Roller or flat tappet camshaft?

Flat tappet sorry I should have said so!

 

[Itali83]

If it’s a flat tappet cam, you need to follow these steps very carefully to make sure your cam survives break in.

1. Make damn sure you are on #1 TDC

2. prime oil pump.

3. drop distributor in and make damn sure your rotor is at #1 terminal and firing order is correct. Tighten distributor mostly but loose enough to turn by hand.

4. Make sure oil and water are full.

5. have timing light already hooked up and ready to rock.

6. have screw driver handy to adjust carb idle to hold it at 2k rpms for you.

7. fill carb float bowl so engine fires as quickly as possible.

8. have a helper crank engine while you are under the hood and adjust distributor if needed. The minute it fires and you show oil pressure, bring idle up to 2k rpms and adjust idle screw to hold it there. Check timing. My rule of thumb is as long as it’s in the 10-15 degrees before TDC, you’ll be all set. Let it sit there for 10-15 minutes at 2k to break in cam and lifters. I do rap the throttle from time to time to vary the rpms.

9. keep an eye on engine temp and oil pressure. It will get hot quick and as long as you aren’t over 210-215 degrees water temp, keep it running. You don’t want to shut it down for anything unless damage from heat, oil loss etc is imminent.

10. Shut it down and let it cool. Restart, adjust carb, timing too off fluids. Go for a ride. Vary speed, don’t be afraid to feed it the beans but do go floating the valves right off. But varying load and rpms are what set the rings in.

It’s stressful but an awesome feeling when the motor lights right off and you get a good break in.

Hope this helps and good luck. Oh, buy the zinc additive or run rotella T 15w-40 diesel oil for break in to help the lifters break in. New oils don’t have zinc which is an additive for flat tappet cam wear.

ben.

 

[Customblue]

Do you feel confident on setting up your timing for initial start up? Local part stores will rent a tool to prime your motor. I would prime then rotate 90 degrees prime for 30 seconds or more. Continue until you complete the full 360 degrees.
Once started, do not let it idle. 2500 to 3000 rpm for minimum 20 mintues. Also, don't fill up with coolant for the break in. After you have it run for the 20+ mintues at +2500 rpms, shut it down and let cool for 4 hours to help temper rings. Keep an eye on oil pressure and engine temperature. Wouldn't let it get hotter than 210

 

[semperfiguy98]

Do you feel confident on setting up your timing for initial start up? Local part stores will rent a tool to prime your motor. I would prime then rotate 90 degrees prime for 30 seconds or more. Continue until you complete the full 360 degrees.
Once started, do not let it idle. 2500 to 3000 rpm for minimum 20 mintues. Also, don't fill up with coolant for the break in. After you have it run for the 20+ mintues at +2500 rpms, shut it down and let cool for 4 hours to help temper rings. Keep an eye on oil pressure and engine temperature. Wouldn't let it get hotter than 210

Do you feel confident on setting up your timing for initial start up? Local part stores will rent a tool to prime your motor. I would prime then rotate 90 degrees prime for 30 seconds or more. Continue until you complete the full 360 degrees.
Once started, do not let it idle. 2500 to 3000 rpm for minimum 20 mintues. Also, don't fill up with coolant for the break in. After you have it run for the 20+ mintues at +2500 rpms, shut it down and let cool for 4 hours to help temper rings. Keep an eye on oil pressure and engine temperature. Wouldn't let it get hotter than 210

Question.. Don't fill it with coolant? Won't it overheat? Or am I misunderstanding? I'm going to be doing the same thing very soon and want to make sure I understand everything.

 

[Blackbeard44]

your gonna want it filled with coolant.
post #1 is spot on

cannot stress it enough that the motor needs to run 2k for 20 minutes

 

[Moach]

may i ask a question what if you are unable to let it run for 20 min. ?

 

[Itali83]

If you need to shut it down before 20 minutes it better be because of something major. Like loss of oil pressure or coolant temp 210+. If you do, fix what ever issue you’re having and resume break in procedure. That’s why it is so critical to just make sure everything is right the first time so you have a smooth break in.

Ben.

 

[Blackbeard44]

pay attention to header primary tubes and manifolds during the break in, if they start to glow red fatten up the carb with more fuel to try and lower EGT temps

 

[Blackbeard44]

after initial break in you should allow it to cool, change the oil and drive it with varying throttle input, dont just hold it at any rmp, keep it moving constantly moving your foot up and down on the pedal, try to keep it under 3,000 for a 100 miles or so, give it another oil change and than start getting on it harder, I usually wont do a WOT pull until i have 750-800 miles on a new motor.

after an oil change at 1,000 miles its time hammer down and drive it as you normaly would

 

[Itali83]

Red hot exhaust can mean late timing as well. That’s why I have a timing light right there and have it at 15-20 degrees BTDC at 2k rpms. It’s be around there or even more once the timing is fully set anyway. And with no load on the engine advanced won’t hurt anything.

Ben.

 

[Ricko1966]

I run rotella 15 40 always not just for break in. I also change my oil hot after breaking in the cam, yep it's kind of a waste of 5 quarts of oil, but I feel better getting any contaminants out that maybe there from the build or the break in immediately, I also change it again at 300 miles. I don't know if anyone mentioned this I also fill my carb float bowls through the vent tubes using a dish soap bottle full of gasoline so it has fuel immediately.If anything does go wrong you can shut it down just don't bring it down slow,and bring it right back up in the 2000 range when you restart it.Italia mentioned he varies the rpm, me too,from 2k to about 2500 up and down for 20 min. One more thing take the thermostat out or wedge it open with an aspirin before first start up.

 

[Customblue]

Fill it with water at first then you drain once you shut her down it so if there is any minor leaks around threads, like head bolts going through water jacket or water pump bolts, it will flash rust and seal them.

 

[wingman50]

Use a Zinc additive in your oil. Especially important for the flat tappet cam. The oil we have today does not have zinc.

You must be registered for see images attach