71 50 HP Timing Check Clarification

[jbuote]

More of a curiosity question than anything else really, and some thoughts from the experts here would be great!!
No, I have no reason or cause to be checking my timing right now, but...

​I was reading the section on checking the full advance timing in my Factory Service Manual.. (Got it from Ken Cook a while back now... )

​It says to check timing:

• ​Engine in test tank, or on boat in lake
• Set engine speed to a minimum 3500 RPM (Full Spark Advance) in neutral or in gear
• Spark advance should be 19? +/- 1?

Simple enough!
​The question though, lies in the "in neutral or in gear"...

I thought I've read on here multiple times, that it should be checked in gear, on lake etc.. for proper loading and not to cause possible runaway...
Neutral was not a good idea..

​The take-away I get from the FSM, is that the backpressure from the water is really enough to prevent runaway in this instance..

​Were there bulletins or updates to the FSM that would obviously not be included in the original manual?

Thanks for reading, and I look forward to your insights!

 

[Joe Reeves]

Back-pressure or not.... Do Not Ever attempt tp open the throttle of any outboard engine in neutral. You could easily encounter a runaway engine whereas the rpms would continue to increase way beyond the limits of the engine to enter the dieseling stage. And as a diesel, to turn the key off or yanking the spark plug wires off would do nothing!... the engine would continue to scream away. By the time you figured out how to stop the engine, connecting rods would usually be flying out the sides of the crankcase.

FYI, The quickest way to stop a runaway engine is to jam a large rag into the carburetor throat... but then, most engines have a face plate attached there now, or have more than one carburetor. Best to avoid that runaway thing to begin with!

 

[jbuote]

Hey Joe!

​Yeah, That's what I've read, and that's the rule I've been going by..
​Just found it interesting that the factory service manual implied that it's "Ok" to do it in Neutral..

​That's what went against everything I've learned thus far!

​And I agree with you about not risking a runaway in the first place!
​Would rather have help on the boat, cruising along to check it, than be swimming for con-rods to be used as sinkers for fishing.. LOL

 

[Joe Reeves]

If you could scan/copy/paste that quote that is in the service manual, I'd like to see it.

 

[jbuote]

Hey Joe,

​So I took a picture of the pages in the manual, then blew up the paragraph that has the statement in question.
​This what you were looking for?




​And the beginning of the section has the "In tank or on boat" notice:




​Thanks Joe!!

 

[boobie]

Can you post a pic of the cover of that manual ??

 

[jbuote]

Here you go boobie!

​This is the cover of the Factory Service manual I received from Ken Cook online for my 71 Johnson 50....
(It's the right manual right? LOL)

 

[Joe Reeves]

Yes, that's the paragraph I wanted to see... I can't believe what I'm reading. There's no way in Hell that I'd have any outboard running at 3500 rpm in neutral in front of my face! Amazing to see that in print in a service manual. I appreciate you going to the trouble to display that JBoute.

Edit: I see, just now that the cover of that manual was inserted... a OMC manual no less. I just happened to have a set of the 1971 service manuals in my file and will be checking into them in the morning.

 

[jbuote]

Not 100% sure on the author Joe..
​I'm presuming OMC since the copyright on the cover states "<circle c copyright image> OUTBOARD MARINE CORPORATION 1971 ALL RIGHTS RESERVED" followed by "LITHO U.S.A 9/70"

Does that help at all?

 

[Joe Reeves]

Couldn't wait... shut the alarm off and looked into the original 1971 50hp OMC Setvice Manual. That paragraph is indeed there on page 4-5. There's even a revised #4-5 page inserted there (by me in 1971)... and that paragraph is even on the replacement page. I have no idea why they would print such a thing. I don't agree with that statement worth a damn! Not something I would ever chance!

 

[jbuote]

Wow!!

​Ok, so it's not just me that thought that was not quite right...
Glad I asked for clarification though...

I wasn't going to do it in Neutral, but...
​If I were new(er) and simply had the manual I might have done it in neutral given that's what the manual says I "Can" do...

​That's another great thing about iBoats forums... I've learned enough about outboards, that I knew NOT to do that...
Nobody at OMC is going to replace my engine when it blows up because I followed the service manual.. LOL

 

[jbuote]

And thank YOU Joe for taking the time to look at your old manuals to confirm it..
Pretty strange...

​I, for one, will most definitely take the word of experience (you) over the manual any day... LOL

Thanks again Joe!

 

[Joe Reeves]

Wow!!

​Ok, so it's not just me that thought that was not quite right...
Glad I asked for clarification though...

I wasn't going to do it in Neutral, but...
​If I were new(er) and simply had the manual I might have done it in neutral given that's what the manual says I "Can" do...

​That's another great thing about iBoats forums... I've learned enough about outboards, that I knew NOT to do that...
Nobody at OMC is going to replace my engine when it blows up because I followed the service manual.. LOL

That shows you have something under your hat that won't be found in any manual!

 

[jbuote]

That shows you have something under your hat that won't be found in any manual!

​Well thanks Joe!

​Looks like we posted at the same time here... hehe...

Well anyway,
​Thanks again for your interest and insight in this Joe Reeves

 

[boobie]

Thank you jbuote ! Somebody at OMC was FN to have put that in a manual.

 

[jbuote]

Hey boobie!!

​I just HOPE that maybe someday, somebody finds this post and sees that it's really an oversight on the manual editors or something, and DO NOT REV IN NEUTRAL!! Even though the manual says you "Can"...

​The REAL take away, and ultimate lesson from all of this is:

1. Manuals are for reference only
2. While many manuals exist, Factory Service Manuals are the BEST reference
3. When a procedure doesn't look right, DON'T do it. Ask for clarification from those who know more than you do.
4. Even the best manuals can have errors...
5. Manuals are for reference only...

You should have SOME knowledge of the subject to back what the manual is trying to tell you...
​And finally, I'll add that Manuals are for Reference only..
​

Does that sound like a fair assessment? LOL!!

Thanks All!!

​Joe

 

[boobie]

YES !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!