1963 75hp Carb Adjustment During Break-In

[yorab]

Motor in signature. I hope to have the break-in done in the next few days. The motor has been completely rebuilt. My manual says to set the carb's slow speed needles to 1 1/4 turns out from seated as a first adjustment. Then do the whole "lean it until it coughs then enrichen until it's smooth" thing. Should I wait until after a few hours of operation before tuning in the slow speed circuit? I'm thinking that the last thing that the motor needs is a lean condition-even for a short time-during break in. Opinions?

 

[Willyclay]

Re: 1963 75hp Carb Adjustment During Break-In

IMHO, making it run "smoothly" should be your number one priority BEFORE starting any break-in procedures because your motor and most two-cycle outboards use the low-speed fuel metering in combination with timing advance for 2/3-3/4 throttle. Then the high-speed jets kick in. Since you need to vary the throttle setting throughout the break-in period, the low-speed adjustment must be set properly. Good luck!

EDIT: Actually, first make sure that beauty is pumping cooling water before you put it in gear and load it up!

 

[tmcalavy]

Re: 1963 75hp Carb Adjustment During Break-In

Good advice from Willyclay. I would also make sure I had a tach hooked up to make sure the motor is in the ideal rpm band/range as you make your carb settings and afterwards. Tinytach has several models...easy to hookup and use, and you can move them to another boat/motor as the occasion arises.

 

[Chris1956]

Re: 1963 75hp Carb Adjustment During Break-In

Just set the idle adjustments to make the motor run as smooth as possible. Lower the idle speed as you get closer to the optimum setting, as the motor will speed up as you make the proper adjustments. Those older motors are not as finicky as the newer ones about the idle mixture. That motor should idle very well, very slow.

Does it have fixed high speed jets? If so, you are lucky..... If not, you need to adjust them while bouncing along at high speed.....

 

[yorab]

Re: 1963 75hp Carb Adjustment During Break-In

Thanks guys. I've got my tach hooked up. I also have fixed high speed. I'll take the advice and set the slow speed before the break-in.

 

[boldtr]

Re: 1963 75hp Carb Adjustment During Break-In

It should idle just fine at 1 1/4 turns out. ONE AT A TIME, you can turn a low-speed needle in 1/8 turn increments...wait 15 seconds for a response and then turn the same needle another 1/8 in. Once you get a cough, you can back it out 1/8 to 1/4 from the cough setting and it should be good. Then move to the other low speed needle and do the same. Since this is a new motor / rebuild you may need to do this twice....once when you first start the motor and warm it up in a test tank while not in gear and then again once you are on the water and put it in gear.