120 HP GM carb idle screw.

Ok, i have a 1972 sea ray that has a 120 HP Inboard engine. I am having an issue with it idling...the problem being that it wont. I can start it in neutral but i have to have the throttle pressed down for it to stay running. There is a hole on one bracket that has threads but i have ran a screw threw it and there is nowhere for the screw to go really. So my question is, how do i get his darn thing to idle. I will attach a picture of the carb,any and all help will be appreciated, and if you haven't noticed im new to the boat world, but i am some what mechanically sound, just not with boats.

how do i get his darn thing to idle.

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Rebuild it by giving it a good 12-24 hour soak in carb cleaner and blow out the idle circuits and venturi w/100 psi compressed air. If it has a single mixture screw it is a Mercarb and requires base gasket # 27-807982. The mixture will not adjust worth a crap w/any other thin gasket. If there are two mixture screws it probably is a Rochester. Buy a Merc. OEM carb kit w/accellerator pump...no aftermarket crap kits. You may need a float if it is heavy. They are cheap so replace it anyway. Make sure the stove pipe on the choke is clear and the exhaust passage in the manifold is not plugged w/exhaust carbon and gunk. If it is then buy an electric choke for it and wire it to a purple ignition wire w/16 ga. wire.
Overhaul kit # 823427A1. You can order the kit above in parts search.

there isnt just a idle screw on the carb......it is a Rochester carb because it has two mixture screws at the front of it.. i just thought maybe it would be like a car carb and have an idle screw i could just adjust. the boat runs good on the water i just have to manually hold the throttle back to shift from neutral into forward. once im in gear it runs fine...when i stop and pull my throttle back into the lock position it will die, so i have to push in the button (to place in neutral) and push the throttle foward and pump it and it will start....and as long as i leave the throttle down a little it will run all day but as soon as i pull the throttle back into the lock position it will die instead of staying at an idle.

check the operation of the shift interrupt switch. Adjust the throttle cable by the barrell nut if needed. IDLE RPM is 650 in gear.

ok thank you

the fuel line is incorrect, rubber should not be on a pressure side. I suspect its a auto carb because the hose from the valve cover does not go there.hi idle cam looks like its backwards

If it's a marine carb it looks like the valve cover is vented to the fuel pump overflow nipple instead of the flame arrestor. Does the fuel pump have a bare nipple on the lower half? It may have an auto fuel pump on it...dangerous if the diaphragm ruptures because it will dump raw gas into the bilge and blow up the boat.

I figured that my hi idle cam was backwards, as far as the fuel lines i will check them today. I have only had the boat for a very short time, and no very very little about the boat or boats in general. As far as the fuel line goes, would the boat still run as good as it does if it is actually in the wrong spot.

Did you check the fuel pump like I said? If it is not a marine pump you have a bomb on board waiting to go off and kill you and the passengers. This diagram shows the fuel pump it should have, the carb and how the valve cover should vent to the flame arrestor. There should be an amber colored plastic hose running from the pump to the carb where the valve cover now vents to the carb. http://www.mercruiserparts.com/Show...4&bdesc=FUEL+PUMP,+FUEL+FILTER+AND+CARBURETOR

Rubber line on the fuel inlet is OK if - and ONLY if, it is rated A-1 hose with approved clamps.

The WOT setting is made by way of the barrel nut on the cable; the idle speed should be set thru the link rod's adjusting nut.

if the fuel pump is original, it may not have the sight tube fitting. You may want to consider the 'newer style' replacement for two reasons: 1) You are highly unlikely to find a service kit for the original pump & 2) it is a much safer design.

Sorry its takin me so long to reply iv been working 12's all week...i have checked the fuel pump and it is a marine fuel pump, as far as the idle i flipped the cam the right way now i just have to re thread the hole were my idle screw goes because it is stripped out pretty bad (probably the reason there wasn't a screw in there in the first place).