Evinrude 115hp to 135hp early motor.

[sparkroost]

Need some advice on carburation. this is a 1973 V4 crossflow. 3.5" bore oversized .064. I am using the tuned exhaust from a 140hp. I have the 140 carbs.<br /><br />My main question is carburation. The carbs have the number 324396 on the front as well as 1 3/8(venturi size?). The jet number on it is 30 and is located on the side of the carb. Air or fuel jet I am not sure of. I do not see anymore jets or orifices other than the main two brass tubes with holes in them. They do not look removeable. they also have no numbers on them.<br /><br />Is it possible to get 135HP from this block? are the exhaust ports lower/higher in the 135hp model? Intake ports different size?<br /><br />As for the tuned exhaust. There is not a "cutout" on the lower end for the exhaust to go straight through. There is that thin strip in the way that carries water. It does not block the exhaust completly.<br /><br />have I gone too far?

 

[Hooty]

Re: Evinrude 115hp to 135hp early motor.

Have a look at this diagram. The main jet is nr. 23. The low speed is nr. 7. I think you're looking (nr. 30) at the low speed jet. The main should be something like a 73 (.073").<br /><br /> Carb <br /><br />c/6<br /><br />Hooty

 

[sparkroost]

Re: Evinrude 115hp to 135hp early motor.

You are right. I didn't see the main jet. It's a 65C. The other is 30. no letters I can see.<br /><br />I am wondering if I need to change the jetting on the low and high side.<br />also, what would I expect to gain from a tuned exhaust and carbs on this model.<br /><br />for 1973 135HP they recommend 73c at sea level but nothing for the low speed jet.<br /><br />thanks for the pic. I don't have that carburator though. I have the late carbs vs. the early ones.

 

[sparkroost]

Re: Evinrude 115hp to 135hp early motor.

ok, I did some searching on this topic. Seems the major thing is the port size. I also read something on the megaphone(the tube that sits in the mid section. I don't have that piece, just the stock one from the 115hp. I also read that the 115's had the bubble exhaust(tuned exhaust)... mine does not.. <br /><br />Is porting common? Expensive? Is it easilly done when boring?<br /><br />I know it seems like alot of work, but I have the engine dissasembled, completly. I just rebuilt the lower unit. This is costing me much less than new. Comments, suggestions please.