Throttle cable adjust

[rob 135]

1973 Johnson 135hp my cable is adjusted all the way and still idles just a bit low . Stalls when put in foward a lot , and every time in reverse. Throttle idle screw on lever fully screwed in . Idle never seems to come back the same , always different . Timing base free ,throttle arm cleaned and lubed.allmoves freely . Could cables be stretched,can I pull slack from cables in control box by loosening set screws.

 

[boobie]

Check the compression on it. And then do a cylinder drop test.

 

[rob 135]

It's all new , fresh rebuild . 130 compression. Carbs done , runs great . Just get idle set right .

 

[emdsapmgr]

The idle on that engine is set by adjusting the idle timing, not the carbs/throttle cable. The throttle cable should not be the determining factory by which the engine idles. Set the idle when the engine is floating in the lake, and is in forward gear. You can't set it when the boat is on the trailer. 650-700 rpm's in gear and under load. You may want to disconnect the throttle cable when making the adjustment so that any binding is not a factor in the idle setting. Are you working from a factory service manual? This is part of the sync-and-link procedure. Once the idle is set correctly, then reconnect the throttle cable and adjust the cable end to meet the stud-in it's current position.

 

[rob 135]

Yes I have manual ,and done link and sync. But can never get idle timing rpm high enough. Screw not long enough. So I ajust up with cabl adjuster. To get rpm up so it won't stall in gear ,but just not enough. Am I doing something wrong .

 

[emdsapmgr]

When at idle, both the butterflys on both carbs should be completely closed. That's part of the sync and link. It is possible to have the two carbs out of adjustment. When the carb butterflys are not closed at idle, you can get idle issues. Remove the airbox cover and visually check them when running.

 

[rob 135]

Let's say link and sync is done , what causes low idle ,I just rebuilt fuel pump . Engine is running on all cylinders. I did carbs once but might have missed something. This low idle is getting the best of me. Runs great other wise . Any body with any help on what causes low idle,with no more ajustment

 

[emdsapmgr]

Low idle timing will cause the engine to idle too slow.

 

[rob 135]

Idle timing is at 10 now . Way high just to get 650 rpm in water

 

[racerone]

The only adjustment for timing is maximum advance at full throttle.-----------Idle timing is given and is the point at which the throttle plates open.----Actual idle timing look after itself the further retarded the better it is.-----Not the same as setting the idle timing on " grandpa's " chevy 283 cubic inch motor.

 

[racerone]

The only adjustment for timing is maximum advance at full throttle.-----------Idle timing is given and is the point at which the throttle plates open.----Actual idle timing look after itself the further retarded the better it is.-----Not the same as setting the idle timing on " grandpa's " chevy 283 cubic inch motor.

 

[emdsapmgr]

10 degrees seems high for idle timing. But, each boat/engine combination is different. The idle depends on how deep the boat lets the engine sit in the water. The deeper it sits, the more backpressure the exhaust gets from the water trying to keep the exhaust from coming out of the prop. So, each boat is different. The optimum timing is whatever degrees it takes to get it to idle at 650 in gear when on the lake with a normal load of gear. Is there a problem with the 650 idle rpm's when in gear? You did not say it was a problem-only that the idle timing seemed high... Running a high-pitch prop will also drop your idle rpm's.

 

[racerone]

Was this motor rebuilt with new pistons in worn out bores ????

 

[rob 135]

It idles ok at 650 in water, just idle ajust screw turned all the way in. Max timing set fine , link and sync fine . Just at max of adjustment. Runs great in water . Wow tri hulls are very heavy boats .

 

[WernerF]

10° BTDC should result in much more than 650 rpm. Normal is some degrees ATDC.
What rpm does the engine idle in neutral? A big difference indicates a heavy load, a small difference a problem elsewhere.
The flywheel key might have sheared and your real timing is not 10°. Compare #1 piston TDC position (through plug hole) with timing pointer 0° position.