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1971 mercury thunderbolt help ???

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bama221989

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Hello i recently purchased a new/old control box. I cleaned it and oil and lubbed all fittings etc.... I have a problem that i can not figure out and could use some help please.

In foward i get little to no throttle like i should and in reverse i get tons of power. The linkage inside is correct and verfied . Any suggeations on why this is happening ? In reverse the lower cable moves comming from the motor. I replaced the hub assembly last year , impeller , and new fuel lines.
 
Those can be hell!

Are you sure you're not confusing the throttle and shift cables? (Been done lots of times, like leaving the plug out!)

Jeff
 
fastjeff said:
Those can be hell!

Are you sure you're not confusing the throttle and shift cables? (Been done lots of times, like leaving the plug out!)

Jeff
Click to expand...

100 percent not sure . in my control box i have the side with the cold start lever attatched to it i have the lever that has a pully attatched to it .. Its the one that goes inside the gear housing ? ... "The plate " with the cutout .. Excuse my lack of knowlege to part names

The other side with the choke and ignition attached inside i have the flat pully attatched .. I have more rev in reverse .

I can see the bottom cable move when i position the shifter in reverse
 
This is what the inside of your Mercontrol should look like. Top pic is throttle side with the fast idle lever.Bottom pic is the gear shift.The track marked G is where the roller on the throttle side advances the throttle cable.If not like this,you may have one of those pull to go boxes which,if my memory serves me right,was for some of the 20HP Mercs.Jeff will be able to correct me if I'm wrong :D
 

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haventaclue said:
This is what the inside of your Mercontrol should look like. Top pic is throttle side with the fast idle lever.Bottom pic is the gear shift.The track marked G is where the roller on the throttle side advances the throttle cable.If not like this,you may have one of those pull to go boxes which,if my memory serves me right,was for some of the 20HP Mercs.Jeff will be able to correct me if I'm wrong :D
Click to expand...

Yes mine looks exactly like that .. Do you think my cables could need replacing ? My papa also had a choke wire comming from the motor and its the only thing i did not hook back up . going to hook it up and see in just a min
 
As Jeff says check the cables at the engine are not on the wrong way 'round,and never forget the bung:eek::eek::eek: or there'll be a lot of water in the boat.
If you are sure the cables are correct,push shift into fwd,go back and turn prop by hand,if it locks one direction and ratchets the other,you are in fwd,if it locks both direction,you are in reverse,and you have a pull to go.
To test cable,and you'll need the breakfast maker :D to help here if the cable end is hard to see from the control.Disconnect cables from the engine,push the shift forward while watching the cable,the one that moves first is the shift.Calculate the distance the shift lever travels before the cable moves,it should be immediately,if more than a couple of degrees,change cable.
Same with throttle cable.Put shift in neutral,lift fast idle lever,cable end should start to move immediately.
 
haventaclue said:
As Jeff says check the cables at the engine are not on the wrong way 'round,and never forget the bung:eek::eek::eek: or there'll be a lot of water in the boat.
If you are sure the cables are correct,push shift into fwd,go back and turn prop by hand,if it locks one direction and ratchets the other,you are in fwd,if it locks both direction,you are in reverse,and you have a pull to go.
To test cable,and you'll need the breakfast maker :D to help here if the cable end is hard to see from the control.Disconnect cables from the engine,push the shift forward while watching the cable,the one that moves first is the shift.Calculate the distance the shift lever travels before the cable moves,it should be immediately,if more than a couple of degrees,change cable.
Same with throttle cable.Put shift in neutral,lift fast idle lever,cable end should start to move immediately.
Click to expand...

Hey thanks for the reply . yes in foward the propeller rotates clockwise and clicks ... Can not move counter clockwise
 
I have tons of power in reverse and little in foward which is opposite. Would it hurt to go in the control box and switch the cables to the opposite pulley ?
 
You MIGHT have one of those assbackwards control boxes. Here's the deal: Merc used a control box that worked the shifter the opposite direction for some Merc 9.8 and 20 hp motors.


Did that control box ever operate YOUR motor correctly?

Jeff
 
I been in business for over 40+ years and never seen a reverse shifting Merc box.. All Mercs pull for throttle and pull for forward. You got a pic or part number for this??? Asked several of my buddys that collect/restore Merc's and they got no info?
 
..." You got a pic or part number for this??? Asked

Where the hell have you been! Merc made thousands of them for 9.8s and 20s. Had several myself. The cam in the box is made assbackwards so the shifting (not the throttle) works the other way around.

Jeff
 
Are you testing in the water when you say you have loads of power in reverse?
This is way out,but what is the prop like?Would you have by a wild stretch of the imagination have a left hand prop?
If you could post a few pics of your set up,control box,engine,connections and for laughs,the prop.
When you put it in fwd ,is the shift lever traveling all the way down,90*,on the control box?
It would be a lot easier changing them at the engine.All you are doing is moving the shift to the throttle and vice versa.
Have you opened the control box?
 
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