Rebuilt 70hp Will Not Start

[trendsetter240]

Re: Rebuilt 70hp Will Not Start

Great work! Now if this is a newly rebuilt motor you should be running on 25:1 fuel/oil mixture during the break in process. Break in should take about 20 hours. Follow the break in guidelines exactly to ensure that your rings set properly and the motor lasts.

After 20 hours you will need to re-torque the head bolts to specification.

As for idle, yes it will run about 300 rpm or so fast on muffs than it would under water. The first thing you should do is ensure that all three throttle body plates are fully closed at idle and the timer base has returned to the correct position.

Have you set the timing on this motor yet?

Cheers

 

[Joe Reeves]

Re: Rebuilt 70hp Will Not Start

I need help setting the idle right. Is it pointless to set the idle on the muffs? In the top secret files when it talks about adjusting the carburetor, what are you supposed to turn?

Nothing to adjust on the carburetors as all of the fuel measuring items are fixed jets. Any screws covering the jets... make sure they're tightly seated. The jets obviously should be tightly seated also.

However, make sure that the linkages connecting the throttle butterflies between the carburetors are set properly, that is all butterflies close completely at the same time (you do not want, for example, two butterflies closed and one slightly open)... and also at full throttle, check to make sure that all of the butterflies are wide open (horizontal).

Also make sure that the throttle butterflies just start to open when the scribe mark on the metal cam is dead center with the throttle cam roller, not before or after. At this point, the idle timing (whatever it states in your manual) should show up via a timing light), usually 3 or 4 degrees BUT look it up to be accurate.

The idle can be set when running on a flushette as follows. In the water, the idle will drop to normal.

20" shaft model = Set the idle to 1000 rpm.

25 " shaft model = Set the idle to 1200 rpm.

 

[daselbee]

Re: Rebuilt 70hp Will Not Start

So he was off on his timing, but not because of a wiring problem. Looks like post #2 has it.
I wonder why it did not backfire. Hmmm......

 

[Socak]

Re: Rebuilt 70hp Will Not Start

Is a timing light necessary? I do not have one, nor understand how they work.