Diff in carb seats ?

[half fast]

Mercury makes two different carb seats and needle sets for the old style two float models.What is the difference ? I just put a stock 150 together all new stuff,six fresh bores ,all new merc .015 over pistons completely rebuilt for a 21 Bay boat for me.It seems very rich at idle and just off idle.It has wh 27 or 47 "I can't remember" carbs that call for 64 hispeed jets and 54 idle air jets and thats what its got.I am not sure which needle and seat kits I installed.We had both in stock at the time and they appeared to be the same.The odd ball ones got ordered and put in stock by mistake.Could this be my rich condition ? I want to figure it out before I attempt to bandaid the problem by leaning out the low side.Fuel pump new,bleed lines new,bleed valves new,fresh new fuel,no oil injection. hf...

[sosmerc]

I just did a carb rebuild today on a 91 vintage 135hp V-6...this one had the single float setup with the accelerator pump on the side. The needle and seats in this carb are TOTALLY different than the dual float setup...I don't think you could mistakenly use these seats in a dual float carb.

[sosmerc]

To the best of my knowledge, all dual float v-6 carbs used the 1395-7824 needle and seats.
I recommend setting the floats "wet"...so that you can confirm float level before installing the carbs. Setting them "wet" means hooking the carb up to a fuel line with the bowl off the carb and pumping them gentle full to see where the fuel level is when the seats shut off the fuel flow. hold the carb level, and pump very slowly on the bulb. You want the fuel level to be just at the point where the curve in the bowl meets the mating surface to the top part of the upper carb body. Be sure the carb bowl is level in a vice.
It takes a little practice, and some time to get both floats to "set" as equal to each other as possible.

[half fast]

The two part numbers in question are 1395-7824 or 1395-7624 ,these are the two shown for that type carb,not the single float carb. hf...

[Raceman]

Since a needle/seat is basically an on/off switch, how could they account for a rich condition unless they're leaking at idle fuel pressure?

In the early days of the Merc V6 Merc had a lot of trouble with the carbs leaking at the needles, even with stock fuel pumps. There was an aftermarket needle/seat arrangement that was used in a lot of cases to fix em. The needle was flat on the bottom instead of tapered and went against a flat seat that had some type of soft seat on it. They'd absolutely fix one that was sloppy down low, or in worst cases flooding out the front.

[sosmerc]

7624 does not supercede up to 7824 so I would gather they are for different applications. If you had "wet set" the floats and were trying to use the wrong needle and seats I think you would have encountered difficulty and thus discovered the problem.

[transomstand]

The 7824 is the common one, used in the majority of engines, including high performance.
The 7624 is used in limited application, WH3A, WH7A,WH9,WH11, looks like very early carb models.

Pete

[T-REX]

Halfazzed, Raceman iz rite on tha leeky seetz...If'in one or 2 carbs are rich, maybe U have a leek'in problem, but it iz easy to see...Juss trim ya mota a lil over zero trim, an let it idle...if it'z tha needle/seetz, ther will be gas runn'in out tha carb front...It could also be a float sett'in doin that too....If ya mota iz fat across tha board at idle, change tha idle jets and don't worry bout it if'in it cleenz up ya problem...All ov the jet listings in merc manuals are reely rich....Make sure them carbs iz stock, and sum genious ain't had thier way wit tha progression holes:eek:

Wh-20's called fer sumpth'in like 48's or 52's in tha idle holes, I have 76's in mine to make it do what I want...Juss treet dat ole mota like ya fantasy winch...U git it what ya want an make it like it...U da boss!!:rolleyes:

[half fast]

Found problem.I ran a six gallon tank today and it ran a ton better.Seems this station had some diesel dumped into the midgrade tank weeks ago by mistake,guess it is not all out of the system.I had put in thirty six gallons a couple of weeks ago along with a gallon of oil to break in with.Just never suspected fresh new fuel as the culprit. hf...

[Superdave]

In the early days of the Merc V6 Merc had a lot of trouble with the carbs leaking at the needles, even with stock fuel pumps. There was an aftermarket needle/seat arrangement that was used in a lot of cases to fix em. The needle was flat on the bottom instead of tapered and went against a flat seat that had some type of soft seat on it. They'd absolutely fix one that was sloppy down low, or in worst cases flooding out the front.
Those were Parker needle & seats. ;) Been trying to find someone that can get them, but having NO luck. Anybody know ???:confused: