Questions about Powerhead break-in??

[sutor623]

I have decided to go with a remanufactured powerhead. Dont have the time to fool with the old block right now, and just want to get back on the water. If I ended up doing a rebuild, I would have wanted to replace all bearings, pistons, etc. to avoid another failure in the near future. So I decided to get an OBR powerhead and keep my old motor for parts if I ever need them. Here is what OBR recommends doing in addition to their break-in procedure:

Install .002 larger main jets in carbs.
Retard max timing 2 degrees. Set max timing with engine running over 4500rpms under load, do not set max timing static.
Replace waterpump.
Install water pressure gauge.
Use mid-grade octane with no alcohol.
Remove oil injection (at least replace to latest VRO).
Double your oil.
Retorque cylinder heads after 10 hours.
Rebuild fuel system.
Check overheat alarm.

Most of this is pretty understandable. Do you guys overjet the carbs with rebuilds/remans or is this an odd practice? How do I get jets that are oversized, do they have them at shop.evinrude?

I use Joe Reeves WOT timing method. Is this not permissible? Also, should I keep the timing 2 degrees retarded?

Is breaking an engine in during the cold months a no-no? Water temp is in the 50's right now. Air temp is 30 in the mornings and 50 during mid-day. Maybe that cold dense air is not a good thing for a fresh break-in?

 

[kbait]

Don't know all your answers, but water temp won't matter as the thermostat(s) keep temp constant once warmed. I've heard that you should use conventional 2-stroke marine oil for break in period, as synthetic may be too slippery for proper wear-in.
Good luck!

 

[sutor623]

Thanks. I am not concerned with operating temp of the heads, it is just the fact of a piece of metal going from 30 degrees to 150 degrees in a few short minutes. Also, on top of that, motors tend to run leaner in the cold because of how much denser the cold air is.

 

[HighTrim]

Covering their buts.

I would not personally worry about water/air temps myself. never have anyways. I would think changing the jet, and retarding the timing, would prolong the life of their powerhead they are selling you perhaps, but at less "performance". Just guessing, never tried.

 

[sutor623]

Covering their buts.

I would not personally worry about water/air temps myself. never have anyways. I would think changing the jet, and retarding the timing, would prolong the life of their powerhead they are selling you perhaps, but at less "performance". Just guessing, never tried.

Thanks bud. This is what they recommend just for break-in. I am assuming that they want you to put in the proper jets and correct the timing after break in. Just an insurance that the motor won't run lean or detonate, I guess.

So basically, through your experience, you have never re-jetted a carb for the sole purpose of breaking in an engine?

 

[emdsapmgr]

Most of the OBR steps are common when installing a new powerhead. New fuel pump, new impeller. Double the oil, but just for the first tank of fuel. Retorque the heads after 10 hours. Test the overheat alarm and if needed, replace the fuel lines under the cowling. All pretty normal stuff. The one thing they did not mention was changing the thermostats. Recommended on a new powerhead. The only time I use oversize jets is when a piston is installed larger than .030 over. Maybe their reman block is .040 over on all pistons-don't know from your commentary. Today's fuel is poor so I understand the fuel concerns. Some states, it's hard to find non-ethanol fuel-like Illinois. I run my crossflows at normal timing (set at 5000) and run stock jets. But I only use 93 octane ethanol fuel. And the Evinrude XD50 synthetic blend oil. I run the old crossflows (79) with the high compression heads and have not had a failure. Having said that, you will find little difference in engine performance if you retard the timing 2 degrees. When breaking in the engine, I'm more concerned with the time spend at various rpm's than the outside temp. The factory service manuals all have excellent engine break-in procedures-hopefully the OBR ones agree with the factory.

 

[sutor623]

EMD, thanks for your input as always!!! The OMC break-in procedure looks great, and the OBR is very similar, maybe a little less tolerant, actually.

Thanks for bringing up the thermostats. They actually change those out as part of the reman. They also change all of the fuel boost ports and check valves too. Pretty solid reman, if I may say so myself.

They claim that they will not bore over .030, so I am still curious about the jetting changes.

Do you think that I should break up the break in period between 4-5 trips, do it all in one day, or maybe in two different days? I know that you said you like to have 6-10 heat/cool cycles before running WOT. When I am breaking it in, that is all that I am going to be focused on. Probably be a pretty boring endeavor, ay?

 

[HighTrim]

How many over did they go? I personally have not re jetted for a break in. I have not gone 40 over either though. But just my own experience, as stated above, Im most concerned with the RPM fluctuations.

Its real hard breaking in a jet boat, lol. You just wanna punch the darn thing!

 

[Faztbullet]

I only go up a size if over .030 and they use pistons made in Italy(WSM). I use a break-in that is used at the factory, with my test prop and running it on water I breakin my rebuilds in 3 hours and that running them at WOT on the lake.Then the customer can do what they want .....

 

[sutor623]

How many over did they go? I personally have not re jetted for a break in. I have not gone 40 over either though. But just my own experience, as stated above, Im most concerned with the RPM fluctuations.

Its real hard breaking in a jet boat, lol. You just wanna punch the darn thing!

Yea keeping a jet boat tamed is quite difficult!!

 

[sutor623]

I only go up a size if over .030 and they use pistons made in Italy(WSM). I use a break-in that is used at the factory, with my test prop and running it on water I breakin my rebuilds in 3 hours and that running them at WOT on the lake.Then the customer can do what they want .....

So you do most of the break in with a test prop?

 

[Faztbullet]

Only the 3000rpm and below on the trailer, rest in on the water with original prop...

 

[sutor623]

Only the 3000rpm and below on the trailer, rest in on the water with original prop...

Gotcha, that sounds like a great plan. Its hard to run 3000rpms on my boat because it wont stay on plane at that speed, even with trim tabs. I am afraid that if I run the boat at 3000 or less, since the boat wont be planed it will "lug" the motor and put an atypical wear on the fresh motor. Maybe I should try and get ahold of a test prop for this reason?

 

[emdsapmgr]

Controlling the rpm's at first startup are important. The factory says that it's ok to exceed 3000 rpm's early on in the break in. The intention is that you want to get the boat quickly on plane. You may well have to run higher rpm's in order to get the boat to plane out. This short time above 3000 rpm's is ok. Once you are on plane, then reduce to 3000 rpm's. The factory does not want you to run a 3500 rpm's for a half hour- plowing water and not being able to get on plane. That situation only burns a lot of fuel and generated a lot of powerhead heat. Not the thing you want during break in. The engine will run much easier once it's on plane-and that's the objective. Put hours on it when the engine runs easy.

 

[sutor623]

Controlling the rpm's at first startup are important. The factory says that it's ok to exceed 3000 rpm's early on in the break in. The intention is that you want to get the boat quickly on plane. You may well have to run higher rpm's in order to get the boat to plane out. This short time above 3000 rpm's is ok. Once you are on plane, then reduce to 3000 rpm's. The factory does not want you to run a 3500 rpm's for a half hour- plowing water and not being able to get on plane. That situation only burns a lot of fuel and generated a lot of powerhead heat. Not the thing you want during break in. The engine will run much easier once it's on plane-and that's the objective. Put hours on it when the engine runs easy.

Thanks man, this what exactly what I was looking for and makes perfect sense.

I talked to OBR, they told me that running a larger jet is optional, and a precautionary measure. Also told me that for my particular engine, 87 octane is ok during break in as long as it is E-Free.

 

[HighTrim]

Yeah, you cannot plow water. No problem punching it to get the boat up on plane, then back off as stated. MUCH better for the motor like that.

 

[racerone]

A test propeller can be used for break in.--------Boat would not have to leave the dock at all.

 

[sutor623]

A test propeller can be used for break in.--------Boat would not have to leave the dock at all.

Sure wish I had access to one of those!

 

[emdsapmgr]

Just wondering what exact engine year/model you are working on. A looper?

 

[sutor623]

Yea, '95 130 90deg looper