Tuning 85 horse carbs

[bashr52]

Finally got my 85/75 frankenstein combo out yesterday. As suggested with a used unknown motor, I'm running 2x the oil through it for the first tank just to make sure everything gets a nice coating of oil. I will go to 50:1 after that. It smokes like crazy though. That, coupled with the seafoam soak I'm sure doesn't help. Anyway, what's the proper procedure for tuning the carbs? Just set them about 3/4 a turn out and leave it, or do you tune at WOT or fast idle for best RPM? I think I may have an issue with the 75 horse carbs being to lean, and may have to turn the mixtures out farther than usual to compensate? Anyone know the size of 85 horse jets, or a place where I can buy some?

Thanks!

 

[jerryjerry05]

Re: Tuning 85 horse carbs

85hp needs to be out 1 to 1 1/8 turn.and let it set. Unless the carbs are 85 on a 75.Then you get into bore /stroke jetting and a few others.J

 

[Frank Acampora]

Re: Tuning 85 horse carbs

MY MANTRA AGAIN! Carbs are like women's breasts: They stick right out in front and men just HAVE to mess with them. And it will get you in trouble.

But here goes:

The 75 carbs usually run about .066 high speed jets with a 1 3/16 venturi. 85 carbs are usually somewhere around 0.074-.080 with a 1 5/16 venturi. Changing jets will screw up the mixture. Want to try a little richer? Raise the float a bit. Never checked but I have a suspicion that they MAY be Holley jets.

First adjust the carbs so all three open equally and substantially horizontal at WOT. Then, at idle--regular idle in neutral--adjust the mixture screws. Start at 1 1/4 turns out from lightly seated and go both ways--look up the past posts for the procedure, it's late and explaining takes longer than doing-- USUALLY the correct setting will be somewhere between 3/4 and 1 turn out from lightly seated.

 

[bashr52]

Re: Tuning 85 horse carbs

Well I don't HAVE to adjust them, but I'm putting my 75 horse carbs on an 85 horse so I figured some adjustment would be necessary. I had to switch power heads thanks to someone running the old engine way lean and cooking 2 cylinders, so I want to make sure I do this one right.