Holley vent whistles

[Michael C Henry]

I had my Holley 1850s redone.When they went away they had the white plastic vent whistles.When they came back to me they had a small brass devise that partialy exposed the vent window diagonaly .It is hung off the pegs that hold the bowl gasket.It is formed from sheet stock. Anyone have experience with these? are they better than the vent whistles?Why do you think they switched ? Should I replace with the new white plastic vent whistles ?

[Woodz428]

To begin with the vent piece of brass you describe is the standard
vent plate. The plastic "whistles" are supposed to prevent fuel from sloshing out vent tubes under hard G forces (cornering,braking and acceleration). I would say thatthey should be installed if you plan on such activities. It makes me curious about the metering blocks. Since the whistle tubes require a small brass rivet to hold them in place, they either left the hole unplugged, plugged it with the regular rivet(minus vent) or swapped metering blocks all together. I would personally suspect the latter since I've never had to remove a whistle to do any carb work. You can look at the metering block and determine if they were ever used with a whistle because of the mentioned rivet/hole.

[427 S/O]

Probably better than the plastic, I used a
piece of aluminum tubing 3/8X1 and compressed one end in a vise, inserted in the housing and rivited. Works great.

[Michael C Henry]

The reply I got from the rebuilder said that the plastic whistle in a side pivot float application may inhibit float travel causing it to not close the needle and seat.

[Big-Foot]

Mike - your rebuilder is correct. The plastic vents were made to be used only on the center-hung float systems. There are new nitrofil (plastic) floats that are far more buoyant than the standard brass floats. If your carb was built using the new plastic floats, the float will ride up much higher and probably contact the whistle. You could use the brass floats and "maybe" get by.
Typically the venting is not a problem unless you are pushing the extremes in acceleration and braking and are having fuel slosh problems (fuel spilling from the vent tubes)..

[Michael C Henry]

If you aren't pushing the G limits then what is a Cobra replica for?They had the whistles before and worked fine .I had the black floats in the secondaries and the pink plastic floats in the primaries.I have the black material in both sides now. I did hear there are two lengths of whistles .What they are or what fits what I'm in the dark.

[Michael C Henry]

I ordered two new extra side hung floats. I'm going to try and notch them for some clearence. I've seen pictures where they alter the floats for special applications. Heck the secondary floats are altered originals that came with the metering plate kit.This situation is even more amunition for not choising dual inline carbs.