Break in fresh built mercruiser 230 out of boat

[carlos515]

Since I don't have my out drive yet, I was thinking to break in my flat tappet cam on land. I have built an engine test stand. Just going to order some electrical gauges .
The carb was rebuilt also , so I am not sure what to set the idle mixture screws at.
I know I have to run the engine at 2000 rpm for 20 minutes .Is there anything else i am missing.
I was going to run the house water hose in one of the engine water hoses.
The motor is a 305 -5.0l 1986 B409807.

 

[Scott Danforth]

run the garden hose into the t-stat housing where the line from the transom shield comes in. make sure you have good water pressure. if you have a 3/4" hose, use it. you want the hose spigot on full.

start engine, bring RPM up to 2000 and let it run for 20 minutes.

idle mix screws at 1.5 turns out. however wont matter as you need to go to 2000 RPM, so anything above closed throttle and you are out of the idle circuit

 

[carlos515]

Thanks Scott ,

 

[Rick Stephens]

IMHO it is a waste of time. Seating rings is best done under load.

 

[achris]

IMHO it is a waste of time. Seating rings is best done under load.

I've never 'run in' a cam. Just built the engine, put it back in the boat (tuned it of course), taken it out and done the ring bed-in, full throttle from about 1500rpm until the engine reaches 3500, then back to 1500. Do that 10 times, rings bedded in, cam run in, end of job. Go home, change the oil, then easy running (no more than about 2/3 throttle and keep idling to a minimum) with constant varying for 10 hours. Next 10 hours, same but with occasional runs up to WOT. Change oil at 20 hours, then drive it like you stole it.

Chris.......

 

[carlos515]

I've never 'run in' a cam. Just built the engine, put it back in the boat (tuned it of course), taken it out and done the ring bed-in, full throttle from about 1500rpm until the engine reaches 3500, then back to 1500. Do that 10 times, rings bedded in, cam run in, end of job. Go home, change the oil, then easy running (no more than about 2/3 throttle and keep idling to a minimum) with constant varying for 10 hours. Next 10 hours, same but with occasional runs up to WOT. Change oil at 20 hours, then drive it like you stole it.

Chris.......

I understand roller cams don't need to be broken in but my machine shop gave me instructions on flat tappet cam break in. If you don't break in a flat tappet properly you can loose the lobes because the lifters don't rotate properly.
I agree that seating the rings is best done under load , but i am worried about loosing my cam .

 

[Scott Danforth]

always best to break in a flat tappet cam

 

[76SeaRay]

From what I have experienced, make sure you use a good break in oil. Do not use synthetic for the break in as rings will not seat properly with synthetic. I have always used Joe Gibbs break (Drive BR30) in oil. I have also done two runs at 2000 to 2500 for 20 minutes each then change the break in oil and filter after the initial break in. I am about a week or two from breaking in my own 5.7L, just have to wire up the harness.

 

[carlos515]

Quick question ,
The brown white wire from the terminal block for the trim sender should be connected to a 12v positive circuit? I am thinking the engine will not start if it does not see a voltage there.
I have my test stand ready for the wiring .

 

[achris]

Nooooo... Brown/white gets hooked to the trim gauge 'sender' terminal. If you don't have a gauge or trim sender, leave it disconnected. The engine circuits don't see the trim sender at all..

 

[carlos515]

Great thanks!!