Carb confusion

ngoodart

Seaman
Joined
Mar 13, 2012
Messages
59
Ok smart guys, I have an interesting dilema. I have a 1984 Mercruiser 2.5L 4cyl with an Alpha 1 drive. During my tune up (recently purchased the boat) I am doing becuase unknown when last was done. I had a issue with not being able to get the Idle RPMS down enough to where they are supposed to be. So after a weeks vacation to Montana, I ordered a carb kit for it, went to disassemble the carb last night and start soaking it I ran across something wierd... So here is my question(s)
I have what I believe is a mercarb (only 1 idle mix screw) I got the air horn off the float bowl no problems there, not starts the miss matching with the book. The accelerator pump doesn't look like the ones in the pictures in the manual for a mercarb it looks like the ones in the Rochester. Also there was no Screen, clip, or check ball in the accelerator pump well. Just a return spring that doesn't want to come out. so I get the insides apart and appears to be more of a resembleance to the Rochester carb the the mercarb, I turned it over to remove the throttle body assembly and to my surprise there are no screws to remove this, looked a little closer and the carb is just a single peice.... the gaskets that came with the kit match up so I don't think that is a problem its just a little strange. Any thoughts as to what type of carberator this is. I know its a marine carb has the stencil in the float bowl still but no tag. If I go by the numbers stamped on the carb it was MFG in August of 83. The boat is an 84 so thats fesilble..... Im stumped as to how to get this thing throughly clean and I don't want to screw it up by trying to use brushes ect to clean out passages...:confused:
 

ngoodart

Seaman
Joined
Mar 13, 2012
Messages
59
Re: Carb confusion

ktb I dont have any right now, I can take some tonight when I get home. I have it soaking to get the gunk out. Was just wondering if anyone has run across a carb like this before.
 

ngoodart

Seaman
Joined
Mar 13, 2012
Messages
59
Re: Carb confusion

As promised here are a few pics of my carberator. I got it put back together and on the boat this morning....grr still have the same problem. When I move the accelerator the butterflys open fully but no fuel comes out of the venturis verfied that there is fuel getting to the Carb. Fuel pressure is in spec and everything went back together well, no fighting and most importantly no extra parts....Any ideas I'm stumped and about reay to give up.
IMAG0115.jpgIMAG0109.jpgIMAG0110.jpgIMAG0111.jpgIMAG0112.jpg
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Carb confusion

That J1223 sticker was the first give away that it wasn't the correct carb for your engine. That spec didn't even exist until 93.
The carbs with the single piece base and midsection were used on the 3.0L in 98, and the 3.0LX in 96 and 97.

Might post all the numbers on the carb and see if we can't figure out which one you have. It may not even be for a 3.0L engine

Untitled5.jpg
 

thumpar

Admiral
Joined
Jun 21, 2007
Messages
6,138
Re: Carb confusion

864940 printed on the side comes up as 2003-2004 3.0l carb. The date code is probably 03 not 83.
 

ngoodart

Seaman
Joined
Mar 13, 2012
Messages
59
Re: Carb confusion

Fantastic, no wonder it wouldn't idle at the correct rpm! Now what do i do? Crap!
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Carb confusion

Get the proper kit for that carb number, rebuild it and see how it runs.
 

ngoodart

Seaman
Joined
Mar 13, 2012
Messages
59
Re: Carb confusion

So just to make sure that I get the correct kit this time, chock one up to a learning expierence For my carb I need to order Sierra Part # 18-7075 correct? I am still figuring out how to decifer the different numbers. When I order parts should I get different main jets? the ones that are in the carb now are 1.65mm and the venturi cluster has 412 stamped on it. I just want to get the right stuff and get this thing running and in the water I'm tired of looking at the "lawn ornament" as my wife calls it.... Thanks for all your help and thanks Don for giving me the Manuals in previous threads.... one last thing, with the different carb will the float drop and level still be set per the manual for the carb that is supposed to be on the boat? Thanks for all your help guys I really do appreciate it
 

Failproof

Petty Officer 1st Class
Joined
Sep 26, 2011
Messages
273
Re: Carb confusion

Are you positive you know which engine is in the boat? Maybe it has been changed around as well? Get the carb finished, and then when back on the boat, make sure the throttle blades (butterflies) close all the way. Then see if it idles high with them fully closed. If so you may need to adjust the mains, and or the air bleeds to get lower idle. Assuming the timing and all else is properly set!!!
 

ngoodart

Seaman
Joined
Mar 13, 2012
Messages
59
Re: Carb confusion

Yes I am positive on the motor, 2.5L 4cyl sn is 6719631. I just want to make sure I order the right kit this time. Any guidance on my previous post about the kit part number would be really appreciated.
 

ngoodart

Seaman
Joined
Mar 13, 2012
Messages
59
Re: Carb confusion

Ok a little google time and now i am really confused i searched the numbers on the carb and came up with listings showing that my carb is for a 5.0l... does anyone know what the part number is for the carb that should be on my motor. I'm lost...please help!
 

ktbarrentine

Lieutenant
Joined
Dec 12, 2011
Messages
1,296
Re: Carb confusion

Ok a little google time and now i am really confused i searched the numbers on the carb and came up with listings showing that my carb is for a 5.0l... does anyone know what the part number is for the carb that should be on my motor. I'm lost...please help!

Mercarb: 3310-860070A2
Rochester: 1351-8480A2 (mallory rebuilt # 9-34002)

Sierra replacement # 1348-818621 1 (18-7610-1)
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Carb confusion

In the picture below, you will find the Pick List (In Red) of the 4 Merc kits you need to rebuild the carb properly.
How those 4 parts convert into an aftermarket kit, I don't have a clue.

Pick list.jpg
 

ngoodart

Seaman
Joined
Mar 13, 2012
Messages
59
Re: Carb confusion

Ok thanks guys, I think im just going to order a remanufactured carb correct for my motor. I appreciate you help
 

thumpar

Admiral
Joined
Jun 21, 2007
Messages
6,138
Re: Carb confusion

Ok thanks guys, I think im just going to order a remanufactured carb correct for my motor. I appreciate you help
That is probably your best solution. You can put the one you have up for sale or maybe the place you buy the carb from would take it for credit toward the new carb.
 

ngoodart

Seaman
Joined
Mar 13, 2012
Messages
59
Re: Carb confusion

Any thoughts on my carb selection from my previous post before I order it? Your guiadance is extremely appreciated.
 
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