Couple more carb questions

T Man44 · Aug 4, 2016

I put a carb kit, new float and bowl on the flo jet carb on my 74 AMF mower. I read that the top adjustment screw should be 2 1/2 turns out and the screw on the bottom of the float bowl one screw out which is what I did. It runs great at full throttle but at half throttle it runs rough, any thoughts on what I should adjust? Also, even with the fuel shut off I still get a slow drip from the screw at the bottom of the float bowl, even with a new bowl and washer. The fuel in the bowl slowly drips. Any thoughts how I could stop this?

BushogPapa · Aug 4, 2016

2 1/2 turns out on the Idle circuit should be very rich ( too much fuel), with the engine running at a good Idle speed, adjust the top screw for "Best Idle".

The bottom screw may not be tight enough, but don't over-do it..

The Bottom screw is the "Power Screw", or Main fuel control for when the engine is running fast and/or under load..

Set that screw with the engine running at "Hi Idle"...(probably about Full Throttle), until you have the engine running smoothly, with no Black smoke..

Usually you can tell if the bottom screw is set too "Lean", if the engine tries to quit, when the throttle is opened quickly..

BushogPapa · Aug 4, 2016

I must caution you about one statement I made that could be miss-interpreted..

The Bottom Screw is NOT itself to be tight..it is the nut that secures the float-bowl that may need to be tightened just a little.. it is next to the float bowl, above the Power Screw..

T Man44 · Aug 5, 2016

Thanks I'll try adjusting the idle screws, I thought 2 1/2 turns was a lot but that's what I read it should be. With the bolt on the bottom of the float bowl I'm sure I have it tight but I'll give it one more snug. I was wondering about putting a fuel resistent sealer between the nut and the bowl, but that could make it a real pain to get that nut off later.

T.R.K. · Aug 5, 2016

You don't say what engine you have. If its a Tecumseh, there is an 0-ring on the bottom adjuster screw, under a washer under the spring which can go bad and then gas follows the threads of the screw out of the bowl.

I am thinking that some of the Briggs engines used a packing around that lower screw. The nut was 2 parts and you tightened the lower part to compress the packing. If the packing nut cannot be tightened any more with normal force, it can probably be helped with 6 or 8 turns of thread behind the packing, to make it compress a little more, and put the nut back on and tighten it.

T Man44 · Aug 6, 2016

It is an 8 hp Briggs. If it needs packing between the nut and the float bowll what could I use, Teflon tape?

T Man44 · Aug 6, 2016

The parts diagram shows the bowl, the washer, then the nut which holds the screw to adjust the fuel. If some sort of packing will stop the drip though I'll do it.

Couple more carb questions

T Man44

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BushogPapa

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BushogPapa

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T Man44

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T.R.K.

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T Man44

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T Man44

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