4 bl carb and intake for 4.3 OMC

[Chum Slick]

Does anyone have a 4 barrel carb and intake for a 1987 4.3 V6 OMC that they would be willing to part with or can suggest where I may find one. I am currently running a 2 bl carb and would like to convert to 4 bl.

 

[Stanp]

Re: 4 bl carb and intake for 4.3 OMC

That's like hang'n diamonds on a jackass! if you want more power, get a bigger engine or a different boat. otherwise, save your money and your fuel economy and leave well enough alone. <br /><br />Oh God, I'm beginning to sound like my wife! truth hurts.

 

[Bob_VT]

Re: 4 bl carb and intake for 4.3 OMC

I have some interesting homework for you to do. Read the link on the Speed Formula posted by JB. <br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=17;t=011044 <br /><br />Do the math using your current set up and write down the results. Now increase the horsepower in the formula by adding say 20 hp which is allot (more than you will get by just changing the carb). <br /><br />I bet the differance in speed is less than 5 mph (and that is at WOT) In a way I agree with Stanp but my theory is .... bigger carb = bigger gas bills. The return on your investment will not be substantial. <br /><br />Consider the formula and consider your goal. That should pave the path to either a total rebuild (cam, carb, pistons, manifolds) or engine replacement. <br /><br />My top speed in theory is 38 mph with my 170 hp I/O (my actual GPS speed is 37). If I swapped out for a 220 hp I would get 45 out of the boat in theory. Heck I rarely run WOT now for a sustained time I like my MPG economy.<br /><br />Bob

 

[Lark40]

Re: 4 bl carb and intake for 4.3 OMC

Guys,<br /><br />Not so fast with the pronouncements.<br /><br />I have the same 1987 OMC 4.3 2-bbl. Now, normally, with car engines, putting a bigger carb on a stock engine is waste of gas and money. That's because the compression, valves, cam, exhaust, etc., also need upgrading to gain significant hp.<br /><br />However, I just looked at my OMC 4.3 parts manual.<br />Hmmmm.....the ONLY difference between the two versions is the manifold and carb. <br /><br />OK - that tells me that you gain 20 hp and 200 rpm by just changing those two parts. <br /><br />Based on these facts, his upgrade notion might make some sense....

 

[Chum Slick]

Re: 4 bl carb and intake for 4.3 OMC

Stanp,<br /> I already have a bigger boat with two bigger engines and one other with a smaller engine. I need another boat like a hole in the head. But if I had your money I would buy another one anyway. <br /> According to what my marine mech tells me, and he is pretty s$it hot, that adding a 4bl carb will increase hp between 20-25. He also suggested that a tru hull exhaust could add another 20 hp. Just doing a little research.<br /> I am not a complete idiot. I am 50 years young and have owned 16 different boats, not counting john boats, canoes, kayaks, float tubes, and fat women to float on. I know the pros and cons of changing carbs I just would like to know a good place to get one.

 

[Lark40]

Re: 4 bl carb and intake for 4.3 OMC

Chum Slick,<br /><br />What is the horsepower of our 1987 OMC 4.3 2-bbl engines?<br /><br />I've been told everything from 160 to 205, and haven't found an authoritative source.<br /><br />Thanks

 

[karayj]

Re: 4 bl carb and intake for 4.3 OMC

I have a 4.3 205 hp i put a 4bl on mine i went for 40 mph to 58+ it works i use the 2 bbl but when i go all 4 you can feel the pick up go to ebay there was one for sale for a 4.3