holley vaporizer

[mike zahorik]

In the past, when confronted with a vaporizer on a Model T, I would recommend changing it an earlier carburetor. After looking at the ones I have seen, the exhaust manifold was either broken or badly warped and the entire unit was running badly. Recently, I came across a vaporizer that looked to be in rather good shape, but would not run a more than an idle. I've been battling vacuum leaks left and right, but seem to be zeroing in on obtaining good running car. The choke spring was broken, all the ones I've seen they are. To replace it you have to remove the choke plate and shaft pin. This one was very stubborn and I had to cut the shaft to get it all out. Lang's has replacement parts, which worked except for the choke plate, it was too big, by nearly 0.025". I had to reform an original. Then after horsing around with a difference vaporizer, I found that Lang's plate fit just fine. Both of these are Holley's, but was there different applications or manufactures that may have used different parts?
One other odd thing was that some of the vaporizers I've seen have a 10x32 machine screw that limits the travel of the weighted air damper. If the screw is in all the way, the damper can only open maybe 30 degrees. Other vaporizers do not have this limiting screw.
I may still recommend not using the vaporizers, they are stubborn, but maybe not. They do work once you get them right. Mike

[Duey_C]

That 10-32 screw is still a bit of a mystery for me too Mike.

[Thorlick]

Mike,

That is the automatic air valve set screw. All of my vaporizer carbs have one.

Ford says the air valve purpose is to automatically control air supply for maximum acceleration. The screw limits the air valve opening.

As near as I can figure it sets the maximum the air valve flapper can open. Screwing it in will effectively increase choke and mixture richness. Screwing it out allows less choking up to maximum air valve opening so a leaner mixture at full throttle and richer at less throttle.

I have never seen directions on how this should be set. I have just fiddled with it and if the car is running well left it alone.

I would welcome hearing a good explanation of how to best set the screw. Also I would like to know the proper screw length as my carbs have come to me with varying lengths and with lock nuts on some.

Vaporizer schematic

[OilyBill]

I have just taken a Holley Vaporizer apart, apparently a very good untouched original. I have been checking each part removed.
On this vaporizer:
A. The stop screw for the swing weight is .750" long, from the bottom of the head, to the end of the screw. It was screwed down all the way, so the swing weight was only opening about 25% of the way.
B. My screw is 8-36 thread. Triple checked with all my machinist tools, under magnification, and that is what it is. Not 8-32, and not 10-32.
I am making a list of each actual thread size, checked from the removed component, and then confirmed by installing a test piece with that thread on it, to insure it actually fits the screw holes.
C. The hot-tube outlet tube, that has the 45 degree cutoff on the end, and sticks into the venturi area has a finger-knurl nut that holds if on. It ALSO has a small copper gasket to assist in sealing. This is confirmed by the Ford parts books. I will post a number, as soon as I find it.
Mine carried the "Holley" nameplate, which looks to be original.
Looking at other Vaporozers, now, to see what differences there are.

[OilyBill]

The tube is labeled as part number 6269.
The copper gasket is labeled as part number 6270.
The knurled brass finger-nut is labeled as part number 6271.

[Duey_C]

Bill, is that 6270 copper gasket in between the 6269 tube and the cast iron-Hot Plate Cover (the bowl holder)?
If so, I need to get in touch with someone we know.
I didn't really like the connection between the tube and the hot plate cover ( bowl holder) but went with it and got lucky.
I put a file to the cast cover to clean it up, screwed it together and snugged the 6271 nut.
Have you unearthed a part number for the cover/(bowl holder and its proper name?
Fascinating research!
Fascinating carburetors!
IF I have my head on square, I used a regular -32 screw, 3/4" long and ran it down for the flapper but it's been two years.
"Lucky" the truck waits patiently for me.
Interesting!
EDIT: He's a three pull, crank start Vapo carb'd truck.