1985 force 125 1976 chrysler 135

[Shifflett115]

I have a 1985 force 125 and a 1976 Chrysler 135 what is interchangeable on both engines , power head , lower unit ect , can I put the electronics from the 125 onto the 135?both motors are 20 in shafts

 

[Frank Acampora]

You can put the more modern ignition on the 135 but you would need to do some small modifications to the top of the block. Lower units are completely different and not swappable. Understand though that the complete powerheads are interchangeable AND if you swap the powerhead onto the midleg, it will work. The cover and cowlings are completely interchangeable as long as you use the complete set.

UNDERSTAND also that the 1976 uses an 18 spline pin drive prop which is becoming difficult to find. The 1976 two piece lower unit is also slower by about 3 MPH than the later one piece lower units. The 1976 power head is rated 135 AT the powerhead while the 125 is rated at the prop so you will not see any performance gain by swapping powerheads. In fact you may see a loss.

 

[Shifflett115]

ok thank you , the lower unit looks exactly the same as the 125 , im getting the motor for some extra parts , what ever i can use off it , how about the trim ?

 

[Shifflett115]

actually just got the model number off it and its a 1977 1359hg does that make a difference in parts interchanging

 

[jerryjerry05]

Post pics of the lowers.
Franks right about the parts swap.
The trim (pics) might work.The electrical can be adapted.
You might have to use the mid section?

 

[Nordin]

Schifflett115, frank and jerryjerry.
The 135Hp had the two piece LU in 1976, BUT in 1977 it had the one piece.

I Think Chrysler intruduced the one piece LU in 1977 on the 3 and 4 cyl. engines and also on the 65Hp twincarb engine (I have one of this 65Hp myself).

SO. Schifflett115 almost everything are swappable from the 135Hp to the 125Hp (not the ign.system, you have to make some modifications as frank mentioned.)

 

[Shifflett115]

Thank you guys for your response it looks like everything will swap between the motors ,the 135 actually has more compression then my 125 the 135 has around 140 across the board the 125 has around 120 across ,are the carbs the same, jetted the same ?

 

[Shifflett115]

what kind of modifications to the 135 powerhead have to be done to fit the newer ignition to it ?

 

[Frank Acampora]

You need to use the stator carrier from the new ignition and you need to drill and tap five 1/4 X 20 holes in the block. Most importantly: You also need to find a spacer about 1/16 inch thick to fit above the top bearing to keep it from riding up in the block, causing the crank cheeks to rub on the inside of the block. I believe this spacer CAN be found on several late Force 40-50 HP engines..

 

[Shifflett115]

Cool thank you ,I may switch out the power heads this winter ,frank would drilling and tapping the holes in the block something you would be interested in doing if I brought the power head up to you ?

 

[fishnski14]

You can put the more modern ignition on the 135 but you would need to do some small modifications to the top of the block. Lower units are completely different and not swappable. Understand though that the complete powerheads are interchangeable AND if you swap the powerhead onto the midleg, it will work. The cover and cowlings are completely interchangeable as long as you use the complete set.

UNDERSTAND also that the 1976 uses an 18 spline pin drive prop which is becoming difficult to find. The 1976 two piece lower unit is also slower by about 3 MPH than the later one piece lower units. The 1976 power head is rated 135 AT the powerhead while the 125 is rated at the prop so you will not see any performance gain by swapping powerheads. In fact you may see a loss.

Shiftlett, going to ask a quick question since the subject came up hopefully it's OK. It was said that the 125 was rated at the prop. If that is so is the 125 stronger than a merc 115?

 

[Frank Acampora]

Yeah, I would do it but I can not receive or send private messages so it would be difficult to get together. Obviously I will not post my address or phone number on the open forum.

The drilling and tapping is not really a difficult job. Use the part as a jig and spot drill all five holes with a 1/4 inch drill. Go just deep enough to leave a dimple. Then drill down with a 3/16 drill far enough so the stock allen head screws will fit but DO NOT drill through into the top crankcase. Be certain to keep the holes perpendicular to the engine block Buy a bottom 1/4 X 20 tap and tap the holes all the way. You will need to start them with a starter tap and finish with the bottom tap. Use plenty of lubricant and tap only 1/2 to 1 turn at a time. Back out the tap after each 1/2 to 1 turn so it does not gall in the aluminum.

Mercury is notorious for under-rating their engines. I doubt if the 125 is actually more powerful than the 115.

 

[Shifflett115]

frank ,you worked on my 125 a few years ago , i still have an old yahoo email adress of yours i can try to send you an email , i would like to come up to you in the off season to get you to drill and tap the holes , i have good machanic skills but rather have someone do it that has done it before