Carburetor conversion

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Oct 19, 2016 | 10:33 PM

#31

Gary Lewis

FTE Legend

Joined: Jul 2010

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From: Northeast, OK

Nope. Too small for mine as it is larger than your 400 CI cutoff - it is a 408.

Oct 21, 2016 | 08:46 PM

#32

LARIAT 85

Cargo Master

Joined: Dec 2004

Posts: 3,362

Likes: 22

From: Florence, SC

Quote:

Originally Posted by matthewq4b

And yes the 4100 is the single most underrated 4bbl ever made. It is superior to Carters, qudrajet's , holley's everything. It is stupid simple can digest filthy dirty fuel with little to no issues. It's super easy to tune and set up. They have excellent throttle response when set up for it. They have like 9 moving parts so they are incredibly reliable. They can easily be converted to AOD applications with stock Ford parts. They accept stock Ford air cleaners with NO issues. They maintain stock install height so no hood clearance issues. Rebuilding is a breeze and any fool with three functioning brain cells can do it.

For mid displacement Ford engines (to 400 Cui street ) it is the best there is. On the small block Fords it is the best vac secondary 4BBL carb by a very wide margin and even today there is no better vac secondary 4bbl carb on the market as far as I'm concerned .

I agree!

Quote:

Originally Posted by matthewq4b

If Ford had kept developing the 4100, Ford performance in the 1970's and early 1980's would have looked a whole lot different (for the better).

I wonder why Ford didn't do that? If they could update and modify the Autolite 2100 into the Motorcraft 2150 to satisfy emissions well into the 1980s, I wonder why they didn't update and modify the Autolite 4100 into a "Motorcraft 4150?" The same technology would have worked, considering the Autolite 4100 is basically an Autolite 2100 with secondaries.

Quote:

Originally Posted by matthewq4b

Holly did attempt to bring the 4100 back to life as the 4010/11 But it was a an abortion it was poorly engineered and had several issues, they strayed away from everything that made the 4100 such a good carb in the first place. Mind you this was during the time period when Holly's quality went for a dump so no surprise.

The Holley 4010 was certainly a disappointment. It looks like they have been improved and are being made again for Summit Racing.

Oct 22, 2016 | 07:31 AM

#33

Franklin2

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From: Virginia

I mentioned this in another thread, any carb with a power valve is not going to have superior fuel control compared to a quadrajet or carter style (edelbrock) with the power system with the needles that hang in the main jets.

The power valve is on-off. Yes it works, yes these are good simple carbs, I like holleys also and they use power valves. That may make them the best carb for you and me, but I don't think they are the "superior" design.

Oct 22, 2016 | 08:14 AM

#34

Gary Lewis

FTE Legend

Joined: Jul 2010

Posts: 32,875

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From: Northeast, OK

Quote:

Originally Posted by Franklin2

Amen, brother!

Most of you know my predilection so I've stayed out of this discussion. But, my bias is really just away from any carb that uses a power valve, a fabric-style accelerator pump, or holds gasoline in with a gasket. If you troll through the many threads on here about problems with carbs, I think you'll find the majority of them have to do with one of those three things. And the power valve has to be #1.

Carbs with a power valve were designed with, in my opinion, a fatal flaw - no check valve ahead of the power valve so any backfire through the carb is probably going to blow it. Plus, as the PV's and accelerator pumps age the fabric is prone to cracking and then lots of extra gas goes into the mix. But you won't have that problem with a Carter/Edelbrock, Rochester, or Street Demon because there is no way for the part to fail and leak gas. To me, that is a superior design.

No, I'm not saying there are no problems with the metering rod-style carbs. Nor am I saying they produce the most power, get the best MPG, etc. I'm just saying they aren't prone to failing like carbs with power valves.

Oct 22, 2016 | 11:47 AM

#35

ArdWrknTrk

pedant

Joined: Jan 2008

Posts: 23,576

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From: EXTREME southwest CT

I realize this is a tangent, but Holley did install two stage powervalves in the 4180's and other carbs if their manual by list number is to be believed.
They also have been installing check valves since 1991 (irrc)

Carters, Eddies, and Autolites do have their advantages, but your objections were addressed L o n g ago.

Oct 22, 2016 | 12:09 PM

#36

Gary Lewis

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From: Northeast, OK

Yes, I know the fatal flaw was addressed - in Holleys only from what I understand, and years after all of these trucks were made. So, the Autolite/Motorcraft carbs still have it, and they've been the topic of discussion lately in this hijacked thread. As for my other two objections, the fabric accelerator pump and holding gas in with gaskets, I think they still stand.

I'm not saying that anything with those things is a terrible carb. I'm just saying that those things have been cause for many, many problems - as seen here on FTE as well as my personal experience. So, I prefer carbs which do not have those "features" for my DD.

Oct 22, 2016 | 12:16 PM

#37

LARIAT 85

Cargo Master

Joined: Dec 2004

Posts: 3,362

Likes: 22

From: Florence, SC

Quote:

Originally Posted by Franklin2

The Quadrajet is a great carburetor, but it is sophisticated with a lot of moving parts. The Edlebrock is also a great carburetor, but the chokes aren't. Neither of these carburetors have the annular discharge boosters found on the Autolite 2100/4100 and Motorcraft 2150 carburetors. These boosters atomize fuel almost as good as fuel injection, and are superior to what is found on other carburetors. Tuned correctly, the annular boosters and thermostatic choke make the Autolite 2100/4100 and Motorcraft 2150 carburetors the most efficient and the most like a fuel injected vehicle than any other carburetor.

Quote:

Originally Posted by Gary Lewis

So, the Autolite/Motorcraft carbs still have it, and they've been the topic of discussion lately in this hijacked thread. As for my other two objections, the fabric accelerator pump and holding gas in with gaskets, I think they still stand.

I think you are exaggerating a bit. The Autolite 2100/4100 and Motorcraft 2150 carburetors are not like a Holley that has the fuel bowls sealed with gaskets. The *only* places these can leak are from the power valve cover and accelerator pump cover. Also, the power valves on these don't blow out nearly as easily as Holley's did. Yes, it *can* happen, but these trucks are over THIRTY years old now, and many of these carburetors are just as old.

I am curious to find out what carburetor Franklin and Gary Lewis thinks is better, in their opinion.

Oct 22, 2016 | 12:54 PM

#38

Gary Lewis

FTE Legend

Joined: Jul 2010

Posts: 32,875

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From: Northeast, OK

With no true data, here are my preferences, assuming the usage is a daily driver and the goal is good economy and part-throttle acceleration. Note that all of these use metering rods, so there's no PV to fail or even wear out. And the accelerator pumps are piston units that are inside the carb so there's no way they can leak. And they all have bowls that are U-shaped with tops that easily come off, so there's no way the bowl nor gaskets can leak fuel - with the exception of early QJets - see below.

Street Demon: This is the newest design of all carbs, having come out just a few years ago, and they took the best parts from several carbs. For instance, it has very small primaries with triple-stack venturi for good metering and part-throttle response. Granted the huge goggle-shaped secondary probably doesn't have the precise metering capable of some carbs, including Holleys, but at WOT I'm not too concerned. And, the recent dyno testing of my engine with the Street Demon vs the Holley showed little gain with a Holley - according to Cory, Tim's engine master, although I don't have the data yet. Also, this carb is available with a polymer bowl to cut the problems inherent in today's gasoline and hot engines. Mine has the polymer bowl. However, I've not yet installed the engine much less driven the truck so I can't yet confirm all of the positives I've read about the carb.
Thermoquad: These carbs got a bad rap because ham-handed mechanics over-tightened the screws and warped the plastic bowls. But, when done right they ran quite well and had the advantage of not heating the fuel, which is a significant problem today, as well as precise primary metering due to small primaries and efficient venturi.
Quadrajet: This comes in a close 2nd to the Thermoquad, and only because it doesn't have the plastic bowl. They are not as complex as most think. However, there are some tricks to fixing the leakage the early ones had in drilled passages in the bottom of the bowl.. In any event, they are easily tuned right on the vehicle due to the metering rods, and even the jets are easily swapped on the vehicle by removing the top. And the secondary opening is very easy to tune on the vehicle.
Carter Air-Valve Secondary (AVS)/Edelbrock Thunder Series: The advantage of this carb over the AFB is that the secondary opening can be tuned very easily. Plus there are 2nd gen carbs out there that use a 2-step metering rod for even more tuning possibilities.
Carter Alumunim Four Barrel (AFB)/Carter Performer Series: Pretty basic 4bbl. Easily tuned on the vehicle with the exception of the secondary opening point, and that is a bear to change.

I will admit that all of these either are, or will have to be used as, electric choke units on our trucks. And an e-choke isn't as good as some form of choke that senses the heat of the engine, like Ford's hot-air arrangement and GM's coil that was recessed in the exhaust crossover passage in the intake. However, millions of them are in use and the chokes are usable.