timing johnson 70hp 1993

[wallfly]

Hi I wonder what the timing should be on this engine. There is a mark says 19 btdc. But, I am confused because in another thread there are instructions to set the timing at full advance and the idle will take care of its self. Is 19 degrees the idle or wot setting for my motor? Help please summer is running and my engine isn't. tom

 

[Bifflefan]

Re: timing johnson 70hp 1993

i have the answer for you:

You need a book.

you set the timing at idle and WOT.
you need to understand what your doing before you do it.

 

[wallfly]

Re: timing johnson 70hp 1993

I do not have a book as soon as I get to the city I will get a book. Its unlikely I'll get a book this evening or this week.But thanks for your response anyway. tom You're your

 

[Dhadley]

Re: timing johnson 70hp 1993

Basically you set the wide open timing stop so that it does not advance beyond 19*. If the linkage is all set correctly the idle timing will be close. The spec in the book is not an absolute for idle but a starting point. How your motor idles has a lot to do with how deep it sits in the water (backpressure in the exhaust), among other things. The idle speed (rpm) is adjusted by advancing or retarding the timing when the carbs are completely closed.

 

[Bifflefan]

Re: timing johnson 70hp 1993

The idle speed (rpm) is adjusted by advancing or retarding the timing when the carbs are completely closed.

That is why i said he needs the book. this concept is not like a 4 stroke and can be confusing.

 

[wallfly]

Re: timing johnson 70hp 1993

Thank you Dhadley, that is what I needed to know. Enjoy summer Tom

 

[tashasdaddy]

Re: timing johnson 70hp 1993

i believe this is the post he is referring to, it works great. with this process you will be shooting for 15 BTC, WOT. http://forums.iboats.com/showthread.php?t=228183

i use this all the time and it does work.

 

[wallfly]

Re: timing johnson 70hp 1993

Thanks I did read that thread. I will use it to double check. What I did was move the timing plate to its full advance stop while idling with the timing light on My idle timing is about 4 degrees btdc and my full advance is 19 btdc. The motor idles pretty fast. Do I adjust its speed with the idle timing stop then the idle needle jets? How does 4 degrees sound ok. I will retime it using the method discribed as well. thank you. tom

 

[wallfly]

Re: timing johnson 70hp 1993

Yes the timing worked out both ways.
I notice the timing plate does not start to move until after the throttle starts to open. It opens a ways before the timing plate starts to get pushed along. I read some where that it should start to advance as the throttle comes off idle if not slightly before. True or false?
thanks again tom