Vaporizer hesitation

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Model T Ford Forum: Forum 2012: Vaporizer hesitation
Top of pagePrevious messageNext messageBottom of page Link to this message  By Val Soupios on Friday, July 13, 2012 - 09:11 pm:

I finally switched my '27 over to a vaporizer carburetor but regardless of how I adjust the mixture I get a slight hesitation when opening the throttle. I also found that to start the car cold you have to choke the life out of it. I rarely use the starter and had to pull the crank through more than ten times with full choke before it would kick over. Is this normal? The car starts fine when warmed up and except for the slight hesitation seems to run fine. Would a float adjustment possibly cure the problem? Any suggestions would be greatly appreciated.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Danial - Veneta OR US Earth Solar System on Friday, July 13, 2012 - 09:14 pm:

My 27 vaporizer has the same issue - gotta choke the crap out of it when it's cold. I just assumed that was the nature of the beast, but maybe not?


Top of pagePrevious messageNext messageBottom of page Link to this message  By mahlon hawker on Friday, July 13, 2012 - 09:43 pm:

My 27 TT is the same.

Remember you have to suck the gas and vapor from the low lying float bowl all the way up through the two tubes to the venturi assembly on the intake manifold. Takes a little doing to get the system primed at first start! Its like a long straw!

Tony


Top of pagePrevious messageNext messageBottom of page Link to this message  By Greg Charland on Friday, July 13, 2012 - 10:05 pm:

Same issue with my vaporizer. Thinking about going with a Holley NH. Anyone have one for sale?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jim Kelsey on Saturday, July 14, 2012 - 01:24 am:

Val:

I run with a vaporizer and an Atlas exhaust manifold on my 1927 Tudor. I have the same issues, even after the car has been run and it sits for twenty-thirty minutes. My car is extremely difficult to start with the crank unless I prime it by hand-cranking a minimum of six times prior to turning the key. I don't have a slight hesitation with the throttle as you described and my car idles wonderfully when the throttle is all the way down. Many guys that look at my car advise me to switch to an NH until they ride or drive in it. After Rick and Tom Carnegie rebuilt the engine, people that have driven it say that it's the most powerful T with a vaporizer they've seen. I don't see a problem with it; then again, it's the only T I've ever owned so it's hard to compare.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Barker, Somerset, England on Saturday, July 14, 2012 - 05:20 am:

Unless run in the last 30 minutes, I have to turn over 4 compressions with the choke out and ignition off. Then, choke in and ignition on, it starts easily.
It runs fine as well, though its tiny venturi may make for less 'top end' power than other carbs.
It's important that the swinging 'thing' in the inlet is free to move, and that the joints are all sealed - the vap plate, the screw joint above it etc.
If it hesitates on opening the throttle, it's probably momentarily weak - that's why many carbs have accelerator pumps. Is it any better a quarter-turn richer?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Val Soupios on Saturday, July 14, 2012 - 10:08 am:

I can deal with the priming issue, it's just a matter of getting used to it. The hesitation is my big concern and I am trying to figure out how to eliminate that issue. The mixture adjustment seems to be much more sensitive than it is on other Model T carburetors that I am running on my other cars. Opening the mixture a 1/4 turn richer does not seem to make a difference and if I open it up more than that it starts to load up. I seem to have less than a half turn of adjustment without encountering other issues.


Top of pagePrevious messageNext messageBottom of page Link to this message  By James A. Mahaffey on Saturday, July 14, 2012 - 10:42 am:

I find it ironic that Ford advertised the new vaporizer as having many advantages. One was "less choke."

The choke strategy is complex, and I can see how it was supposed to work. Rotary valves in the choke-shaft completely re-configure the carburetor, letting the vacuum pull raw gasoline into the intake structure. Unfortunately, for this to work as intended, the valves must not leak any air. This may have worked when the car was sparkling new, but realistically I can't see the valve surfaces remaining tight for very long. The hesitation on acceleration is due simply to the long path for fuel vapor.

Wishing to restore my 27 tudor to authentic condition, I too wanted a vaporizer to replace my NH. I found that the Kingston B-1 "gasifier", which as installed on a small number of Ts near the end of production, was in several ways the better design. After about 40 years of searching I found a like-new example. I am thrilled by its performance.

For one thing, acceleration is instantaneous, and in this way it outperforms the NH. Fuel economy is definitely improved, as is engine horse power.

The choke, as well as other design features, is a completely different concept from the Ford/Holley vaporizer. A jet is installed at the mouth of the intake manifold, in back of the throttle, pointed up at a 45-degree angle. In choke mode, raw gasoline is sprayed into the intake. It's a minimum distance to the intake ports, and it's a downhill run. Choke is instant.

In fact, it's easy to flood the engine upon choke, and a flooded Model T engine acts completely dead. There is an adjustment: An auxiliary needle valve is provided on the face of the carburetor. Ford mistakenly labelled this the "low speed needle," which indicates that Ford engineers never really understood the Kingston B-1. It's not a idling screw. It's the choke adjustment valve.

Operation of the Kingston vaporizer is ingenious, and I will be studying it and evaluating its performance under various conditions for many years.

Jim


Top of pagePrevious messageNext messageBottom of page Link to this message  By Val Soupios on Saturday, July 14, 2012 - 12:41 pm:

I really want to keep a correct carburetor on the '27 but must admit that the NH I was running before was much better. I will tinker with the vaporizer I have and try to rebuild another one from the other vaporizers I picked up over the year and hopefully I can get the issues down to a minimum and get used to the slight hesitation. Thanks to everyone for the help. At least now I know its the carburetor and not me!


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