MTFCA Forum

I took apart the vaporizer off my 27 Tudor that is market “Holley” and it has a larger float than the two others I have marked “Ford.” I did some searching around it was mentioned that this was done to assist in controlling the higher head pressure from the cowl mounted tank. I was wondering if anyone has found this to be true? The larger float is also going to decrease the amount of fuel in the bowl, would this be a problem on hills? I know the elevated tank addressed the hill problem just curious about which float would be best to use. Right now I have a small float in and have intermittent overflows and starvations. Float level was set prior to assembly with a new Viton tipped valve. Float was tested for leaks. Obviously got an issue somewhere but was just wondering about the difference in floats.

The larger float is not only larger but heavier. Its design increases buoyancy to offset the higher head pressure of the gasoline. It belongs in your vaporizer and is set normally. Your fuel level in the bowl is going to be just fine, though the capacity of the bowl is somewhat reduced which makes the throughput of the float valve critical.

As for starvation, my guess is that this is happening either at higher speeds or during hill climbing...if this is true, then you are simply too restricted with an off-the-shelf float valve. They are all designed with a too-small through-hole.

As far as overflow, from the looks of the float, the whole carb needs a good cleaning and the supply of fuel needs cleaning up or else junk will hold the valve open regardless of the size of the float. Since it is a gravity-fed system, there is always some risk of leakage over time and the use of the shut-off lever at the sediment bowl is a mandatory safety feature.

Scott, That dirty float came out of the original vaporizer as found in the barn sitting for 53 years lol. Never ran that one yet that’s why I took it apart. I picked up a couple others that I cleaned and rebuilt but have not had much luck with. Car runs too poorly to take out on the open road right now and has been relegated to driving up and down my private road for testing and tweaking. The second carb I put on runs better but hesitates badly when trying to accelerate and will stall occasionally. A little tap tap on the bowl will get it going again but the hesitation remains. It will idle fine. Making progress with it just working out the kinks. I’m fairly new to the T’s and have heard good and bad about the vaporizers I’m learning the bad and searching for the good

John

vaporizer-type carbs are extraordinarily sensitive to vacuum leaks...meaning they can tolerate NO vacuum leaks. If everything is CLEANCLEANCLEAN, then ensure that you have a good mixture needle which is sharp (not ground down blunt) and has no groove in it due to aggressive crashing into the jet.

If you are having to constantly tap the bowl, then the float is riding along the inside of the bowl or from the casting that goes through it. Tweek the hinge so that it swings freely with no extraneous movement other than up/down. On the lifting tab, there will be almost certainly a tiny divot worn into it where it lifts the float valve. YOU MUST POLISH THIS DIVOT OUT ! Also, the lifting tab on the float must be curved and its arc generally parallel to the float. If the tab is straight and a simple ramp, then it will always be sliding the valve sideways while lifting and that will bind "open" frequently. The curve in the lifting tab should be such that in every position of the float from hanging down to all the way up, the tab in contact with the float valve should present perpendicular to the valve. A tab shaped thusly, with no divot to hang up on the valve, will stop your hang-up problems nearly certainly.

With respect to any fuel starvation issues, feel free to contact me by email for the solution to that.

Scott:I'm sure impressed by the way you provide technical advice and instructions. Obviously from many years of experience and maybe even a teaching background. Anyway your input is always correct, to the point, and easy to follow and very much appreciated. What a great contribution you make to an already amazing Model T site.

When I rebuilt my late ‘26 NH a vendor told me I had the incorrect float and to get the A version. Said mine was probably off an old tractor. I suspect he didn’t know about the mid-year change by Ford to the larger B float for cowl tank cars. I’ve been fighting mine for several years since. I’ve been asking around for one and haven’t found one yet. My float works well on a half tank or less Full tank and hiccups occur. If anybody has some spare B size floats they can part with Please mssg me.