throttle and rpm setting

[Jconnell43]

1971 Johnson 50
Having trouble keeping it idling, runs rough, rebuilt carbs,good gas.
Can I loosen the clamp that joins the 2 carbs so that both throttle plates are closed, then tighten them in that position then and use the roller position to open them slightly against the cam, I have a feeling one is more open than the other.Is there a better way?
Also I have seen that timing is not an issue at idle, but how many threads should be showing ( roughly ) on the throttle rod with the clovis pin?
Thanks,
Jim

 

[jbuote]

Hey there!!
​I have a 71 50 hp too.. New to me last August, so I'm still learning about mine too..
​
​Yeah.. You should be able to loosen the clamps, get both carbs closed, tighten it, Just be sure that when you push on the roller, BOTH throttle plates start opening at the same time..

​Not sure offhand about threads showing, or how many inches (or fractions of), but here's an old pic of mine..


​Now, I'll ask....

Have you done a compression test on it?
​Have you checked spark with an open air gap tester set for 7/16" gap?

 

[David Young]

My factory repair manual for my 1977 70hp does show measurements for the throttle rod. I'm pretty sure yours would be different than mine. Maybe look into buying a factory repair manual. I gave $40 for mine and have saved over $1,000 being able to do things myself

 

[Jconnell43]

No compression test, might try one though.
Spark on both cylinders is good.
Have taken pics and movies of engine while running and my settings are way different than your pic although I may change it to look like yours.
Have generic repair manual, may keep eyes peeled for specific manual.

 

[clemsonfor]

Looks a lot like my 69ish 25 I use to have

 

[Jconnell43]

Bad news, rented compression tester and ran it 3 times after crankig for 5 seconds each time.
Top cyl 120 psi, bottom cyl 60 psi.
Too far gone for decarbing?
Any advice?

 

[ondarvr]

Since it's cheap you could try a de-carb, but I wouldn't expect much, or just pull the head off and take a peak

 

[Jconnell43]

Can't get it running for long enough to spray Seafoam.
Might try cranking it for a while to get it warm then tilt engine up and pour seafoam into cylinder and leave overnite.

Unless someone has a better idea?

 

[ondarvr]

If you crank it long enough to warm it up you will fry the starter. Pull the head off and look.

 

[jakedaawg]

Can't get it running for long enough to spray Seafoam.
Might try cranking it for a while to get it warm then tilt engine up and pour seafoam into cylinder and leave overnite.

Unless someone has a better idea?

I have never heard of a worse idea...

 

[boobie]

As said above, pull the head off and check it. It may be just a blown head gasket !!

 

[Jconnell43]

No Title

Nothing wrong with this head gasket !!!
Cylinder walls seem smooth, I think I'll do a brake cleaner spray to clean the crud out.

Anything else to look at while I'm here?

 

[Driftwood Jim]

The bottom ring of the gasket looks to be toasted and the metal ring broken. This will not hold pressure.

 

[boobie]

Your head gasket is BLOWN !! Needs a new one.

 

[Jconnell43]

Just kidding, new one on the way for $12.49.

Head is easier to take off than the thermostat cover, had it off in 20 minutes, left thermostat cover on and took them off together

 

[jbuote]

Well,
​Since you found a problem, I wouldn't change yours to look closer to mine... (If you still planned to.. lol)
​Mine is new to me as of last August (Oh, dang. .It's been a year!! haha) , but I haven't had to adjust it that much.. It works on my engine.. Might not on yours..
​Yours may already be set ok for your engine once the head gasket is fixed.. :noidea:

​As suggested, a factory service manual, and adjust as needed for your application..
​You said you rebuilt the carbs, so maybe another once over on them while waiting for the gasket, and then a link N sync once head gasket installed?

​No expert, but at this point I wouldn't go messing with those adjustments until what you found Is fixed..
(You may have already decided not to, but... LOL)

​For what it's worth..