Does this look right?

[FillupD]

This is a 50 HP 1973 Lark. I am trying and trying to get this thing to rev up past 3000 RPM's under load. I am almost thinking that the linkage may be adjusted wrong or the prop is too big.
This motor came off of a fiberglass 15' boat (old) and is on a 16' Lund fishing boat.
I can run it with the muffs at high Rpm's but when it hits the lake the RPM's drop off. It sounds like it runs good and will run up and down the lake but just won't get up and go. I have completed all testing and everything you can think of to do to this thing so I'm reaching now.

Here is what it looks like.

 

[tashasdaddy]

Re: Does this look right?

link does not work. have you check compression, spark, link n sinc, cleaned and rebuilt the carbs. properly adjusted the slow speed needle?

 

[FillupD]

Re: Does this look right?

I'll try to get link to work. I have completed all adjustments, cleaning, ect. It just looks like the arm hits the stopper before the carbs hardly open at all. Then it is all throttle. The timer base hits the stopper about 1/5 throttle but the timing is at 19 at 3000 RPM's. I'm not sure if the the timer base should stop so soon?

 

[5150abf]

Re: Does this look right?

The throttle linckage should move all the way forward not the timing arm, if your timing is at 19 it is right or very close to right.

If you move that any farther you will advance your timing way too much and make the engine run poorly at best and likely damage it, I would leave it alone.

If it won't rev past 300rpm I would suspect your carbs aren't as clean as you think they are, the high speed jet is loacated behind the drain screw on the float bowl, you will need a very skinny screw driver to get to it, run some stranded copper wire through it and see what that does.

I would really avoid setting things so they "look Right" you will only cause yourself problems.

Get a factory manual here at iboats or on ebay, it will have all the info you will ever need to work on your motor.

 

[FillupD]

Re: Does this look right?

I have looked at the high speed jets a couple of times. They look very clean and have been soaked in carb cleaner. The manual states that they are not removable. It sure sounds like those jets are the problem, but it just dosen't point that way. Maybe replace the bowl with jets and see what that may do?

 

[FillupD]

Re: Does this look right?

I took it out to the boat ramp on the trailer and ran the motor and tried to adjust mixture, checked timing again. Looked at the plugs and they are wet and black. Changed pluge with new ones and after a short time of fiddling around they where black laso. I think this thing is loading up and I have the float set dead level. Shall I try to change the float a little or look elsewhere.
I think the linkage is OK now. I hope this link works if you wish to take a look.