Holley 1850 float settings??

[DanEC]

Anyone know the recommended float setting for Holley 1850 with non-external adjustable float bowls? I noticed my front carb (lead carb) is weeping into the intake on the primary throats when I shut it off hot. I have insulator gaskets under the carbs and the float bowl temperatures were around 116 degrees at shut down so I suspected the float setting is a little high in the primary bowl.

In this photo the right bowl is the primary and the left is the secondary. On the primary I can insert a 5/16 inch bit under the outside end of the bowl before the end curve. On the secondary I can insert a 3/8 inch bit. So the primary end float setting is higher which goes along with my theory.



I've Googled a lot and can not find any rebuild instructions for non-adjustable bowl 1850 carbs. I found some internet threads that suggested that with the bowl inverted, the top of the float should be approximately level or slightly higher (lower when right side up). Anyone know the Holley spec?

If I can't come up with anything I will probably adjust the primary side to match the secondary side since it is dry - of course it doesn't have an idle circuit.

[DanEC]

Also, can someone verify these are Nitrophyl floats and not Duracon (plastic) floats? I did finally find some information on the Holley technical site but I'm still trying to sort it out.

[DanEC]

After some more Googling I found several references to Duracon (plastic) floats as white. So I have Nitrophyl floats and can go from there with the Holley tech sheet settings.

[zrayr]

I never met a Holley carb in the last 50 years that didn't perform better when the float was set lower than when set to the Holley specification.

Z

[DanEC]

Originally Posted by zrayr

I never met a Holley carb in the last 50 years that didn't perform better when the float was set lower than when set to the Holley specification.

Z

That's my intent. This carb (2-4bbl intake) is weeping fuel after shutdown in the primary throats of this one carb when hot. Also braking for a turn killed the engine the other day - although it fired right up. Expected to find the floats set too high but they are actually just barely low on the primary side and quite a bit low on the secondary. Possibly the needle/seat has some gunk on it. I plan to lower the primary just a bit more, clean everything and see what happens.

Thanks

[Tim7139]

Originally Posted by zrayr

I never met a Holley carb in the last 50 years that didn't perform better when the float was set lower than when set to the Holley specification.

Z

Interesting point. Given that and the fact that Quick Fuel carbs can be considered "cousins" if you will, any reason to believe that holds for them as well?

Part of the reason I ask is that since I recently replaced my primary power valve on a SS780 Ive had to reset the primary float level and although the primary is about at factory spec [middle of the window] I have the secondary float just a wee bit low and it seems to be an improvement. Since I'm not gonna dyno test it with little tweeks, your post got me wondering.

[Gaz64]

Originally Posted by zrayr

I never met a Holley carb in the last 50 years that didn't perform better when the float was set lower than when set to the Holley specification.

Z

That's an interesting point.

How many flats down from the "true level" do you set your floats Ray?

[DanEC]

I had thought about chunking the fixed float bowls on these 1850 carbs with their non-external adjustment float bowls but I've gotten enough practice removing these things now and dry adjusting the floats that I don't know if there is anything to be gained from doing so. Interesting to note that the Holley specs for dry adjustment are pretty specific and result in a higher primary bowl than the secondary bowl. The theory being that braking and slight forward tilt of the carb contribute to the secondary bowl flooding the carb under hard braking unless the secondary side is a little lower.

They don't go into this on the wet bowl - external adjustment instructions. They basically call for a float setting that results in a slight trickle when the side plug is removed. Unless the primary and secondary bowls have the side plugs at slightly different levels, the fuel settings would seem to end up being the same by this approach. Of course none of this takes into account our 400 to 600 HP motors in 2600 lb cars that probably accelerate nearly as hard as they stop. I guess that's when you need to turn to the baffle and extension accessories.

And then if you run the Ford dual quad intake on your FE, the carbs are backwards - which is something further to re-think. I finally ended up setting my primary floats about 1/32 lower than Holley's instructions and raised the secondary floats up to match so they are basically equal. This is basically a street car so I'm not concerned with trying to get the last tenth out of it. I'll run it like this unless I start encountering some plug, flooding or fouling issues.

And by the way - don't waste time on Holley's support service. I sent them too questions (how to stop fuel percolation out of the accelerator pump circuit and should I reverse float settings on backwards mounted carbs) and there responses indicated a knowledge of carb theory and practices that's no higher than mine - "don't go lower than the recommended float levels", "if your carburetors are mounted backwards I guess you might try reversing float levels" and "Sounds like your fuel is boiling - you may need to use non-ethanol fuel or insulate your fuel line". They are pretty much a waste of effort.

[Gaz64]

The externally adjustable bowls do have different height level plugs.

The secondary level if set as high the primary will flood the motor on heavy braking when the carb/s are mounted normally. That's why the sight plug is lower.

When they are mounted backwards for distributor clearance, now the primary will flood the engine on heavy braking.

The reason for why the rear barrels flood the engine on heavy braking is the main well is all liquid fuel while not on the main system.

[DanEC]

Thanks for the clarification. I have an old Holley 4150 on an old Corvette but I never noticed the side plugs were at different levels. Sounds like on cars with the carbs mounted backwards, dry setting the floats may work better than setting them by the bowl side ports.

[crenbbf]

Dan,

We had the same issue,we set our dual quads as per Hollies spec. and they dribbled.

In the end we set them pretty much like your LHS float (brass in our case) in your photograph and are now OK

cheers

[zrayr]

Originally Posted by Gaz64

That's an interesting point.

How many flats down from the "true level" do you set your floats Ray?

It depends on the car of course. With my vintage Paxton GT350's running a Holley 650 Street HP carb, I would often have to turn at least 4 flats from the stock setting, sometimes a full turn. This was not a supercharger issue, the carbs ran the same way with the blower disconnected. Maybe it's a cautious approach on Holleys part, but the float levels seems to be consistanly way too high on most every Holley carb I've met.

Even when running the supercharged cars on high speed long distance endurance runs of over 100 miles at maximum RPM (In west Texas) I have never ran the float chamber dry with a dramacally lowered float.

Z

[Gaz64]

Originally Posted by zrayr

It depends on the car of course. With my vintage Paxton GT350's running a Holley 650 Street HP carb, I would often have to turn at least 4 flats from the stock setting, sometimes a full turn. This was not a supercharger issue, the carbs ran the same way with the blower disconnected. Maybe it's a cautious approach on Holleys part, but the float levels seems to be consistanly way too high on most every Holley carb I've met.

Even when running the supercharged cars on high speed long distance endurance runs of over 100 miles at maximum RPM (In west Texas) I have never ran the float chamber dry with a dramacally lowered float.

Z

Im glad you share that point of view.

I thought I was nuts at one point, and my friends thought so also.

I would set the level at "just" trickle, bit hard with a cam as we know, lol.

Then I'd experiment lower the levels a few flats at time, at not notice any power loss etc, so drop them again, somewhere the 3-6 flats from memory.

Any QFT, Holley HP etc with windows I run in the bottom third of the window.

Gary