Too rich - secondary float adjustments Holley

RoadRunning · May 2, 2020

Amateur here been SLOWLY rebuilding this 70 Road Runner 383 engine and have it running with a new 4160 Holley carb. The car has been reeking of gasoline every time we start it up. Today we (I think successfully) adjusted the floats on the primary bowl of the carb, gas was too high in the bowl so we lowered the floats so gas is below the sight line now. The gas smell is much better now but still things are running rich. A lot of exhaust is coming out the pipes. No gas leaks that I can see anywhere. Couple questions, we did not adjust the secondary bowl yet, could that be the cause of gas also at idle if there is too much gas in the secondary bowl? We are going to check the air adjustment screws by hooking a vacuum gauge to it as well. Lots of exhaust coming out also, any thoughts? Thanks!

bm02tj · May 2, 2020

Depends on the exact carb you have it may have a balance tube between the bowls
so you should adjust the secondary float as well

turbine68rt · May 2, 2020

I remember buying a 4160 new and had trouble with it within months. It would run excessively rich, smoked, until I would snug the float bowl screws down and it would immediately clear up. Few months later same thing. Had to keep doing it until one of the screws broke off. Must have had a warped bowl, body, whatever. Got another rebuilt one and no trouble after that.

91r/t · May 2, 2020

Check your idle transfer slot location too to make sure it isn't running off the idle circuit ad the main fuel circuit too. You want them set so they are square visually like below. Yes adjust both float bowls to ensure fuel isn't flooding the carb at idle.

bm02tj · May 2, 2020

turbine68rt said:
I remember buying a 4160 new and had trouble with it within months. It would run excessively rich, smoked, until I would snug the float bowl screws down and it would immediately clear up. Few months later same thing. Had to keep doing it until one of the screws broke off. Must have had a warped bowl, body, whatever. Got another rebuilt one and no trouble after that.

That is a common problem that is fixable by flexing the metering block strait so you get no vacuum leak to the power valve

Moparnocar · May 2, 2020

Possible leaking powervalve, or open too early. Look at vac at idle, stock.pw usually open at 6.5, it's in the side of the valve

Cornfed · May 3, 2020

Replying because I recently had a similar Holley 4160 issue on my 71 383.

Just my thoughts, please follow the advice from the others here, they know a lot more than me.

The balance tube is an open passage between both float chambers, above the normal fuel level. It could transfer flooding fuel from the secondary bowl into the primary. So I vote for bm02tj's suggestion, check the secondary bowl and needle situation.

BIGSHCLUNK · May 3, 2020

Had that as a major issue years ago... secondary throttle adjustment

BSB67 · May 3, 2020

Is the problem only at idle? What is the idle rpm? What is the initial ignition timing?, what intake manifold? And what camshaft?

And yes, if the secondary float is too high, it will bleed fuel out the secondary booster. You can look to see if that is happening.

Woodruff Carbs · May 3, 2020

Agreed, where is the timing? This fuel needs a little more time to burn.

RoadRunning · May 5, 2020

Thanks guys for the great responses. Going to adjust the secondary floats and check the vacuum and go from there. These responses help in case I need to dig even deeper also. Not sure when I’ll get time to work on it but will try to provide update later. Thanks.

RoadRunning · May 6, 2020

Checked the oil via dip stick, smelled like gas mixed with the oil. Going to adjust the secondary floats and check the vacuum then change the oil.

Too rich - secondary float adjustments Holley

RoadRunning

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bm02tj

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turbine68rt

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91r/t

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bm02tj

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Cornfed

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BIGSHCLUNK

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RoadRunning

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