New Marine SBC 350 Break In steps and procedure, Timing? Rings? Cam?

[AshleysRevenge]

Sorry if this has already been asked a thousand times, and if so just point me in the right direction.

This is a 83' boat that just had a motor from first mate marine put in with new, well everything almost. New SEI 106 stern drive. Log style manifolds New. Y pipe old. Seakamp 4068F cooling system. New high output alt. new batteries new water pump all new hose. new intake new ect...

So the wife has spent the better portion of 7k on all this and I don't know much about breaking in a new motor (GM350LAFHOT). I don't want to screw things up here. So any advice, so I don't destroy the new toy would be much appreciated.

Old motor died July 13, 2014. Tonight May 7, 2015 she runs again.

Thanks in advance,
David

 

[AshleysRevenge]

P.S. I have installed a new engine timer which only works when oil pressure is sensed through a oil pressure switch. So leaving the key on won't run the timer. This way I can accurately stay on some what of a schedule for the break in. New tac and GPS speedometer as well. Tonight we started the motor after some problems. Had to replace the solenoid in the starter ( not the slave but the one in/on the starter) Fixed. Found out the key in the impeller fell out, fixed that. She idles a 190 degrees. Now that I've read that Idling is not a good thing for a new motor. I am waiting for some advice.

 

[Alumarine]

Here's some advice based on my limited knowledge.

If it's a flat tappet motor you should run it at around 1500 rpm's for 20 minutes or so to break in the cam/tappets.
Use 30 weight diesel oil.
For the first 10 hours run it at varying rpm's with the occasional short burst to WOT. After that, change the oil and just run it.

Someone with more experience might come along.

 

[flipbro]

Get a good break in additive high zinc add to your oil. Run her at 2000 rpm for 20 min. DO NOT IDEAL THE ENGINE. Change oil then avoid starting and idealing after that until youve run it on the lake as Marc said always run a good oil with 1600 to 1800 ppm zddp good luck have fun

 

[AshleysRevenge]

Thanks. We added some zddp to the oil got it roughly timed and are taking it to the water... let you know how it goes.

 

[flipbro]

I recommend running it on land to break in the cam. Hook up your water supply and run her at 2000 for twenty then after that time her and cheak for water leaks or other leaks. After that hit the lake..

 

[AshleysRevenge]

I do to but sometimes women don't want to listen.

 

[JustJason]

If it was rebuilt correctly just run it.

 

[alldodge]

P.S. I have installed a new engine timer which only works when oil pressure is sensed through a oil pressure switch. So leaving the key on won't run the timer. This way I can accurately stay on some what of a schedule for the break in. New tac and GPS speedometer as well. Tonight we started the motor after some problems. Had to replace the solenoid in the starter ( not the slave but the one in/on the starter) Fixed. Found out the key in the impeller fell out, fixed that. She idles a 190 degrees. Now that I've read that Idling is not a good thing for a new motor. I am waiting for some advice.

I hope you gauge is not accurate, your should be idling around the 140 to 160 degree area. If you have a 180 degree thermostat, replace it. Just stay out of the high rpm band for the first 20 hours and try to keep idling to a minimum. Other wise don't worry about it

 

[AshleysRevenge]

Okay the boat speaks for itself... put it in the water got about 500 feet and tried to get to a higher than idle rpm, nothing over 1100 rpm. Carb seemed to be the problem which would make sense being that it has sat since last July. Got back home and messed with the carb a little. It is sticking. So with muffs on got it at 2k rpm and let it sit for 20 minutes. Then 1.5k for 10 the 1.8k for 10 I think we turned it off then. BTY wife says its running 180 Guess I can't read. SeaKamp put a 160 t-stat in there I think. So were off to try and make sure the carb is okay. Along with the stiff/slackness in the throttle cable.

 

[NHGuy]

Warm it up a bit (with varying rpms), above idle. Then shut it off and change that break in oil.
Now work on the tune. Set your timing to 8 degrees at idle rpm, idle around 725 in neutral. That will fall down to around 675 in gear, btw.
Lube your throttle cable by oiling or greasing the end near the carburetor.
With the motor off, check that it opens the throttle all the way. To do that prop open the choke plate and secondary doors with a pen or something and have somebody push the throttle stick to wide open in forward gear while you watch the throttle bores. The throttle plates are at the bottom of the carb and they are wide open when they are perfectly vertical.
Maybe you will find you were not timed right or not getting full throttle. That could explain the 1100 rpm.

 

[AshleysRevenge]

So to reconfirm according to the gauge it is 185 190 with according to seakamp a 160 t-stat.

We are going to look for a rebuilt carb tomorrow and see how that goes. Seems the throttle cable might be in question too.


Thank you NHGuy
We will try that in the morning.

 

[AshleysRevenge]

got a new 140 degree t stat. Got timing set to 8 btdc. At 2000rpm I have 20 degrees of advance. Does that sound right? Won't be able to run her again until the carb comes back from the shop. Thank you all