What's an IHC Teapot Carburetor?

Hi,
According to The Carburetor Doctor "... Governed models were used on IHC trucks into the early 1970's..." I never heard of these "teapot" carburetors before.

It appears a lot of effort was put into their design and they surely must have been much more expensive to manufacture, but why? What can anyone tell me about them? Can they be tuned like a regular carb? Are they more powerful, smoother or more economical to run?
What was supposed to be their benefit or how were they supposed to be better than a regular carburetor? Were they better, the ultimate carb, or just an over-engineered towering pile of junk? Do they have any advantages over a standard carb?

I never saw such a carb before in my life. Thought I'd include a couple pictures of one in case there are others who have never seen one before.
If anyone knows anything about them, please share. Let me know what's up with them, and if known, which models of trucks they were optioned for etc. Just really curious.

Thanks.
Steve
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Ford used them as well. It places the float bowl away from engine heat. I don't know how successful it was but we don't see many.
I think the sole purpose was to prevent "boiling" of gas in the float bowl and engine flooding on hard run truck engines.
The Carter Thermoquad was another attempt at the same problem.
Put another way, it places the float bowl in the relatively cool intake air stream, and isolated somewhat from the engine heat coming up from the manifold.
2bbl version were found on many truck engines, 4 BBL were on the larger 6's and V8's. The RD inline series used them as did some LV 8's.

I wonder if Carbking has tea parties with teapot carbs? Just wondering.

I wonder if Carbking has tea parties with teapot carbs? Just wondering.

May be he is a coffee drinker and likes a percolator!

I guess one of the biggest denigrators of them say a large backfire places the forces of the expanding gases and flame squarely on the float chamber. I guess theoretically, it could blast the float chamber loose and release the gasoline into the backfire, but haven't heard widespread problems with them.

Thank you for the information, cb.
I think I will just stay with my little Holley 2-barrel. I'm not that much of a tea drinker anyway.

Not sure where the term "teapot" originated; back in the day, we referred to them as "haystack Holleys".

The 4-barrel design, as used by IHC, was a continuance of the 2-barrel design which came out in 1952, replacing the older AA-1 2-barrel on larger engines.

The 2-barrel was type 1901, and was used by Ford, Mercury, as well as IHC. These were heavy-duty truck carburetors, and regardless of the various disturbed pixels on the internet, were virtually bulletproof.

The first 4-barrel to used this design was the 2140 which debuted in 1954. The 2140 was used by IHC up through the 1974 model year. It as also used by Ford, Mercury, Lincoln, Dodge, and was used for many military applications because the design was so rugged. Again, virtually bulletproof. Many of these units were fitted by Holley with throttle shaft BEARINGS, as well as seals.

The 2140 was slightly modified for passenger use, to become the 4000. Ford used these on the T-Bird, as well as factory dual quad and supercharger versions. I personally ran one more than 200,000 miles after a rebuild.

The haystack does seem to have acquired a bad reputation, apparently a vehicle using one caught fire, and also caught the attention of the news media. Many "parrots" on the internet have continued to badmouth the design, probably never having seen a haystack Holley.

The biggest drawback to the design today is the lack of availability of rebuilding parts. Yes, we still make rebuilding kits for all of them; but was forced to remove the secondary diaphragm from our kits a few years ago because my American supplier would not do a minimum run of 1000 diaphragms. I understand that there is one available that is being made on the other side of the world, but I refuse to sell other than USA-produced parts.

There are two "gotchas" as described in various Holley service letters: (1) the large washer on the original air cleaner stud MUST be used to seal the plug used for the idle circuit access holes, and (2) the secondary air bleeds are tiny, and can plug in really dusty service. These should be checked at some reasonable interval (depending on the type of service). A secondary function of these air bleeds is to break the syphon effect of the secondary jet circuit.

Most passenger use went to the end-bowl Holley (type 4150) when it debuted in 1957. If you are old enough to remember, hoods were trending down, and hood clearance became a premium. The end-bowl Holleys are significantly shorter than the haystacks.

And finally, yes carbking DOES enjoy his tea!

EDIT: Steve, just reread your original questions. Yes, all of the haystack Holleys are very tunable. All have removable/replaceable idle tubes, main metering jets, power (economiser) valves, and power valve actuating valves.

Jon.

Don't know if it is different terms in different parts of the country (like hogs head, third member and drop out on rears) but I always heard them called tea-pot. I had an IHC 406 which should have come with a 1901 but was a replacement block for a 450 and had its externals. Not sure why IHC used different carbs on the 406 and 450.
Thanks for the history lesson.

Don't know if it is different terms in different parts of the country (like hogs head, third member and drop out on rears) but I always heard them called tea-pot. I had an IHC 406 which should have come with a 1901 but was a replacement block for a 450 and had its externals. Not sure why IHC used different carbs on the 406 and 450.
Thanks for the history lesson.

CB - I would certainly agree on different parts of the country. Would doubt even here in the Midwest that many can remember actually seeing a real haystack. I not only remember them, I remember stacking them. But you couldn't slide down the haystack if there wasn't one, so guess stacking them wasn't so bad.

The teapot name seems to be the current term, and has been for a long time, but I still remember the haystack terminology.

Also remember when the end-bowl Holleys came out, and the standard joke with then current mechanics was to cough each time they said the word Holley.

Jon.

I see Haystacks in MT in some places and I bet in Amish country you might still find them. Not sure why I see them in MT, they have some religious "colonies" up there but the ones I've been to are big on modern equipment.