Carb jet sizes.

[LubeDude]

My manual for some reason doesnt list the WH-30 carb for the 1987 or so Black max 150-175. Does someone have the jetting #s both air and main for that carb for all cylinders.

 

[ob]

Re: Carb jet sizes.

The drawings I can find list different carb #s for different cylinders.WHM 30 - WHM 34 carbs for 150 - 200 hp.Do you have a serial number for that engine?<br /><br />Example : carb jets listed for a random serial number on a 150-175 Merc/Mar list jets as follows<br /><br />175 hp engine<br />progression air jet .050<br />bowl vent jet .084<br />idle air bleed jet .048<br />main fuel jet .064<br /><br />Here's a site that list some of the breakdowns. web page

 

[LubeDude]

Re: Carb jet sizes.

Thanks, Ill find the serial # and post it.<br /><br />The main jets are now 64s, but the Idle air bleeds are 70s. This will make the engine Idle very lean if my calculations are correct. Bigger #, = more air meaning leaner. There are no jets in the front of the venturi opening, I know some dont have them but they are threaded.<br /><br />This is a set of carbs Im working over to install this spring. The carbs on the engine are the same carb #, and has 64s for mains, and 54 for Idle air jets. Im going to drop to 48s on the Idle side, and go up to 66s on the mains.<br />Im right at sea level here so things seem a bit lean on both ends.<br /><br />Thanks for the link, very helpfull.

 

[Laddies]

Re: Carb jet sizes.

LubeDude the missing back drag jets are pretty common in the V/6 carbs, on alot of the engines they would cause a off idle lean condition so rather than the dealers playing around and finding the right size jets (and it did take alot of time going up one step at a time till you find the right size) the dealers would simple throw them away---Bob

 

[crbenny]

Re: Carb jet sizes.

I have the '87 135 Blackmax and have heard the only difference between the 150 and 135 is jets. Is this true and if not, what is the difference?