SBC breakin time

Paintman1960

Paintman1960

Petty Officer 2nd Class
Joined
Apr 21, 2021
Messages
155
Hello everyone, Hope all is well. I just rebuilt a 383 for my boat. My question is, How many hrs would you all consider before changing out the oil? Where I go takes about 3 hrs to complete the trip. Thank you.
 
P

Pmt133

Senior Chief Petty Officer
Joined
Jan 6, 2022
Messages
762
I did my first change a little short... about 11 hours. Then the second one at 37 additional hours. I had a suspicion of water intrusion which is why I changed early.
 
alldodge

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
42,690
Merc says it's more important to keep away from WOT for first 10 hours and only for short periods until 20 hours. Vary the throttle often

My guess is you won't won't get 20 hours on it in the first season unless your real close to water

If you don't make it, I would still change the oil at end of season
 
Scott Danforth

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
50,414
Stock build or performance?
Flat tappet cam or roller?

If flat tappet, the first 20 minutes are critical for cam break in. 20 -30 minutes at 2000 RPM.

No less than 10 hours, no more than 30.
Vary the load and RPM. After the first 5 hours or so start getting closer to WOT for short runs.

If you did a performance build with quality rings, you can cut that time a bit
 
Paintman1960

Paintman1960

Petty Officer 2nd Class
Joined
Apr 21, 2021
Messages
155
Scott Danforth said:
Stock build or performance?
Flat tappet cam or roller?

If flat tappet, the first 20 minutes are critical for cam break in. 20 -30 minutes at 2000 RPM.

No less than 10 hours, no more than 30.
Vary the load and RPM. After the first 5 hours or so start getting closer to WOT for short runs.

If you did a performance build with quality rings, you can cut that time a bit
Click to expand...
Roller , Performance build , good stuff, built and broken in many street builds.
Just unsure on hours wise, on a boat. Using conventional oil for break in.
It's a big river I cruise it on, Thought i'd see what you folks thought about it .

Had my share of flat tappets , PITA
 
You must log in or register to reply here.
Top