Pony Carbs in Mustang Times

CZLN6":1q65f89c said:

Howdy All:

Gentlemen- may I point out that the 1.08 is rated at 287 cfm. The 1.14 is rated at 300 cfm. Both have throttle bores of 1.55". All else appears to be identical. The only variable is the inner diameter of the venturis. My conclusion is that the venturi diameter is the determining factor in CFM.

Adios, David

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Thank you for that supporting evidence, David.

It is physically impossible for the CV of a system to be larger than the CV of it's most restrictive part. That is just common sense.

If you hook a garden hose into a 10' sewer pipe, how much is it going to flow - the amount of the garden hose, or the amount of the pipe ?

While it is true that a venturi is one of the least restrictive forms of flow constriction, it is still a restriction.

In this case, we are talking about reducing the cross sectional flow area by over 50%, which by any measure qualifies as a "significant restriction".

Now, cross sectional area isn't the whole story when you are talking about CV's, but it is a big part of it. Surface finish, transitions, bends, etc all factor in significantly.

The Frenchtown Flyer runs larger throttle bodies on his 350 holleys.
All the carburetor specialty shops offer thinned throttle shafts & oversizebutterflys for increased performance.
My opinion is they would not offer these options if it had no benifit.
Monday i'll call one of the specialty shops & get some flow numbers.

It requires more than a bigger hole in the log to handle more carb. It also requires more total flow, ie, cam, valves, ports, headers, exhaust, whatever. I'm sure my tri power wouldn't help me any had I not done the rest of it. I too ran afoul with Jon back when I started looking up carbs. He basically told me he wouldn't sell me three vaporizers cuz he thought they wouldn't work and I'd be coming back at him with complaints. I don't think he realized I would actually complete the head upgrades and stuff. I have read several sources that agree that a stock 200 head will only flow about 500 CFM. After all, a cylinder has is only so big and a piston can only travel so far, but it needs to be able to suck in everything it can. I'd hafta' believe that my head will flow more than 500 now simply cuz it has less restriction! I don't think that three 1100's with 1.20 venturies each will overload the flow characteristics. I could be wrong, I already have been a couple of times this morning, but I drive my six every day and I know what it does now compared to a year ago. I will very soon change the carbs to try to get a better idle. I'll be using 3 1100's this time.

I have not raced mine yet 'cuz I still need a shift kit, high stall converter, lower diff gears, and I just located a Maverick 4 lug 8" rear axle. After all that goes in I'll go down to Jegs and get on their dyno. Regardless, there has been a marked increase in power, especially at higher speeds, in spite of what I have been warned 'wouldn't' happen by the gloomy Guss's. I really don't expect to turn 15 second times, but I won't be suffering 20 second times either. Thus is the reality of a 'daily driver'.

I'm waiting for that tri power manifold to come available before I buy that aluminum head. I still believe that three barrels spaced along the length of a log will do better than two or four barrels jammed into the center.

I wonder if Santa can get this kind of stuff!

Harry

In case your wondering, the above post were editted by yours truely.

So far, all we've heard are assumptions, opinions, and theories. I for one would like to see some concrete proof, one way or the other, via flow testing and/or dyno results. I'd do it, but then I'd be accused of being bias because I’m trying to sell something, so I guess that's out.

I do feel the above comments are somewhat useless; as they don't take several other factors into account, such as velocity, flow restrictions, etc. While the cross sectional area of the venturi is a limiting factor, the primary function is to achieve a pressure differential in which to introduce fuel. If it were merely to restrict airflow, an orifice (or restrictor plate) would be much cheaper to produce.

One point that hasn't been considered is the change in velocity. When cramming two smaller holes into one large hole, the velocity decreases. On the other hand, cramming two big holes into a smaller hole increases velocity. While increased velocity is generally a good thing, it can be detrimental to the airflow when navigating tight bends. At a given point the air moves so fast it simply can't make the required bend, hence the airflow stagnates. This is precisely why we port our cylinder heads, and unshroud the valves. If you ever talk with a good porter, they will tell you to much porting can actually decrease airflow, which happens when the velocity exceeds a specific speed for a given radius.

I don't know if this is the case when using a 2V adaptor, but I'd have to guess that it's certainly a possibility. The flow when exiting the carb base is actually moving towards the centerline, then is required to navigate a ninety-degree plus bend in the opposite direction. That certainly can't be a favorable situation, can it? I certainly don't know, as all this is way over my head. Like everyone else, I'm just tossing out some thoughts.

Like I said, I'd like to see some flow test results and a few dyno runs, which would at least offer some evidence one way or the other. So far all the conclusions and assumptions have been based on incomplete facts and theories. So who’s right and who's wrong? Who knows....

When cramming two smaller holes into one large hole, the velocity decreases. On the other hand, cramming two big holes into a smaller hole increases velocity.

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thanks for editing the thread.

i just want to point out that your not cramming, your pulling.

pulling through a smaller hole will decrease the amount of air your pulling through the venturis, and pulling less air through the same size opening will decrease its speed. sure the velocity will be greater at the hole in the log, but it would potentially be less at the venturi.

I say potentially because the carburetor your using may be small enough that it won't matter.

Patrick66":2se909qu said:

i just want to point out that your not cramming, your pulling.

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Is the motor sucking air in, or is atmospheric pressure pushing the air in? How about if its under boost? I merely used that term, because it was used in a previous post.

Bort62":2se909qu said:

So while it is a case of trying to cram two holes into one, it is more accurately a case of trying to cram two small holes into one big one, which is a perfectly acceptable way to go.

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I say potentially because the carburetor your using may be small enough that it won't matter.

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Again, more assumptions. Why would the smaller size make less of a difference?

if your using a large carburetor, and the venturis can outflow the 1 1/2" hole in your log, then at WOT you wont be pulling air at the velocity your supposed to be though the venturis. if the venturis on your carburetor are small enough to still be the smallest orifice in the 'flow path', then it shouldnt matter. because the venturis will still be where the most restriction is and the highest velocity.

if the hole in your head (whatever size or shape you or Ford made it) can support the carburetor you choose, thats the important thing. if your using a carburetor thats small enough that you can still use the single 1.5" hole, your probably not getting the most out of your carb upgrade. bigger hole/flow, the larger carburetor you can use. and more air in and out is the goal. obviously the hole isn't the only factor (far from it), but you cant do much with the 1.5" hole in the log, no matter what you bolt on it. i guess what im saying is that using an adapter limits your choice in carburetors, and i don't think its worth it when you can direct mount one. why limit your potential, when you don't have to?


i wasnt trying to be argumentative, i hope it doesnt come off that way.

Mike you are right, the air is pushed into the engine by atmospheric pressure, but it sure feels like it is sucking when you put your hand over the carb.

At a given point the air moves so fast it simply can't make the required bend, hence the airflow stagnates.

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I can't say I agree with this. This makes it sound like there is a point where flow velocity increases to a point and then dies or "stagnates". Air flow is governed to a maximum velocity of the speed of sound, but we are not operating at that velocity in the intake runner on these stock engines. I know what you meant to say, but actually, fast moving air that meets a bend does not stagnate. It goes into more turbulence, which increases the friction and less pressure differential will be available at the venturi. Greater friction also reduces the pressure differential avilable to push the air into the cylinder.

I do feel the above comments are somewhat useless; as they don't take several other factors into account, such as velocity, flow restrictions, etc. While the cross sectional area of the venturi is a limiting factor, the primary function is to achieve a pressure differential in which to introduce fuel.

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Again, more assumptions. Why would the smaller size make less of a difference?

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I guess I am confused on what comments are useless and assumptions. What exactly are we arguing here now?

It is neither an assumption or useless fact that you can flow two pipes into one and not lose any flow capacity through the two pipes as long as the pipe they are flowing into has a larger cross section than the two pipes. And if you remove restrictions downstream of the venturis, be it porting or thinner throttle valves and shafts, then the total friction losses of the whole system will be reduced. That will have the effect of increasing the differntial across the venturi, and the venturi will be able to flow more air. Fact is though, that it all has to pass through the venturi. So Bill, you are right that you can affect the flow capacity through a system by minimizing friction losses. But as Ian stated, the maximum flow is going to be governed by the venturi diameter. And as Mike pointed out the purpose of the venturi is to provide a pressure differential that will allow atmospheric pressure to force fuel out of the fuel bowl and through the jets into the low pressure region at the downstream of the venturi.

Now is all this fussing and "assumptions' & "useless comments" about whether or not a 2 into 1 adapter is capable of moving as much air as a direct mount carburetor? No one has ever stated that the carb sitting on the adapter will out-perform a direct mounted unit. It is obvious that the adapter would generate additional friction if nothing else because it has additional length. (but that is an assumption on my part. Many times spacers under carbs increase top end horsepower, so maybe I would be surprised)

The reason a 2 bbl on top of the adapter offers increased performance is because the 2 bbl carb is bigger than the 1 bbl that came on the cars. I had the following specs handy. The larger 1 bbl YF carb in 1973 had a 1.38" dia venturi which is 1.495 sq in of flow area. The 32/36 Weber I installed has a 26/27 mm primaries. These have a total area of 1.71 sq inches. A 1.75" dia openning on the intake manifold has 2.4 sq in. A 1.50" openning has 1.76 sq in. The small 32/36 Weber is still the flow restriction in the system, not the intake openning. You can put a larger 1 bbl carb on the engine too, but at one point, your venturi diameter gets too large and the air flow at low speeds woulod be too low to generate sufficient pressure differential for the carb to operate well across the whole range. In order to get sufficient pressue differntial for the carb to operate at lower speed, you can use progressive carbs like the Weber 32/36. The carb will run on the smaller primary venturi until the engine speed requires addition flow capacity from the secondary venturi.

You can also help the drivability at low speeds of a large 1 bbl carb by adding annular boosters. The boosters are a small venturi that provide pressure differentials sufficient to operate the carb at the low speed regions. If you are going for maximum performance though, the annular boosters will reduce the flow capacity of the carb because they represent a reduction in the crossectional area upstream of the main venturi.

Those of us that have mounted the 2 into 1 adapter are not seeking maximum performance but rather a modest increase in performance and drivability. Heck if I was concerned about generating WOT horsepower and was worried about minimizing every little piece of friction in the system, I would have tossed the 6 cyl engine and shoehorned a $20,000 powerplant into the engine bay.
Doug

Doug, extremely well put.

Mike, thank you for removing the insults and other unnecessary stuff from the thread. I'm glad to see it wasn't just MY posts that were edited...

I don't think anyone is going to argue that a 2 into 1 2bbl adapter is as good or better than a direct mount. Certainly the direct mount benefits from a more direct flow path to the cylinders, if nothing else. As Doug stated, second order benefits (increase plenum volume) may out weight second order losses (less direct flow path) but we won't know that without much more complicated analysis. Dyno testing could easily show either to work better. Who knows.

The question, however, is whether or not the 2 into 1 adapter w/ a 2bbl can be any better than a 1bbl alone.

I think the definitive answer to this, both from the analytical and empirical side (How many of you running a 2 into 1 adapter feel that it works better than the 1bb? Most... ), is yes. With modestly sized 2bbls (1.08 Autolite, 5200, etc) the venturi still represents the lowest CV part in the system.

As such, it will have the largest differential pressure across it and serve as the limiting factor in terms of max flow at a given pressure drop. The statement by John of not being able to cram two holes into one would, on the surface, seem correct - however when the actual size of the holes is considered it can easily be demonstrated that it is not correct in this circumstance.

This isn't theory, this is just fact. The smallest orifice in the system will be the dominant flow restriction. With a 1.75" carb to intake hole, the pair of 1.08" venturis are still the smallest orifice, and hence the dominant restriction. Changing the 1.75" hole to a 5" hole will effect the SYSTEM CV slightly, but only by a very small (fractional) percentage. It is similar to putting a 4" exhaust on your stock manifold. Yes, it is slightly less restrictive, but in reality - you aren't doing yourself much good. The manifold is by far the most restrictive part of the system.

In addition to the added flow capacity of a 2bbl over a single 1bbl, a progressive 2bbl has the benefit of a much stronger venturi vacuum signal at low throttle. This is a huge advantage when it comes to fuel metering and will help low end tuneability and driveability immensely (as many who have used the 5200 on this board will testify).

A non-progressive 2bbl (autolite, holley 2300) won't give any advantage in that regard, but it does have some significant advantages in overall design.

The available one barrels are extremely simple carbs that achieve general performance by compromise. I had to ditch the 1bbl in my turbo setup (YF) because it's single metering rod/jet setup would not allow me to have sufficient fuel @ WOT (boost) and still have control over my fuel at part throttle.

It lacked adjustability because of the extreme simplicity of it's design. The Holley and Autolite 2bbls have more complex, and hence, more adjustable fuel metering schemes which allow them to meet a broader range of demands.

With all of this in mind, I think we can pretty easily conclude that mounting a 2bbl carb to the log via an adapter can certainly give better all around performance than running a 1bbl carb alone. It accomplishes this both by reducing the airflow restriction to the cylinders as well as by providing a more tunable interface.

It may not perform as well as a direct mounted 2bbl for various reasons, but it certainly should outperform a 1bbl.

This conclusion is based both on the analytical musings of myself and others in this thread as well as the empirical results of dozens, if not hundreds, of members on this board who have observed notable improvements in fuel economy, driveability, and performance when doing this modification.

John @ Pony's lack of understanding of the subject is understandable, and
merely suggests that he has not taken the time to look at the issue beyond the surface. If just asked offhand prior to this discussion, I would myself have probably come to the same conclusion he did. Sometimes, first impressions can be wrong. It's perfectly normal.

If anyone wants to read/learn more about flow restrictions and how to quantify them and make calculations based on that, this article is pretty good. It is specific to valves, but a carburetor is really just an air valve when you think about it...

http://www.engvalves.com/itemfiles/dv06computations.pdf

I've got more info on this type of thing if anyone wants to go there. I've done a fair amount of work modeling the flow characteristics of plumbing systems as well as injectors for rocket engines. It can be a fairly anti-intuitive thing on occasion, and has a steep learning curve. I am commenting on this subject from the position of having "seen the light" so to speak on system flow performance. From that position, some things seem more obvious to me than they probably would have 3-4 years ago (and than they would to someone who hasn't spent weeks fighting through the head scratching parts of figuring out fundamental fluid dynamics).

I'm rooting around my notes trying to find the equations (for summation of CV's) that make the point I'm trying to illustrate clear - but so far, no luck. Perhaps in the "hardcore" section we can start a thread on expressing the performance of a carb-intake-valve-exhaust "system" in terms of CV, and get a real handle on quantifying it's performance.

I've been contemplating that approach for a while.

Bort 62 wrote

John @ Pony's lack of understanding of the subject is understandable

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My interpretation from what Jon stated, was he does not believe in adapters, since they screw up the air fuel mixture & proper atomization of fuel.
He feels its nothing but aggrivation & wasted time on the phone to baby sit novices who do this. I don't blame him at all.
I maybe wrong, but the dyno tests of his vaporizer carb showed that this carb puts out.
Take it for what its worth. Bill

wsa111":18x9b58o said:

I maybe wrong, but the dyno tests of his vaporizer carb showed that this carb puts out.
Take it for what its worth. Bill

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This is probably tangential to the whole conversation, but...

We're still waiting for someone -- anyone -- to give us a real-world appraisal of the Pony 1100. Until such time, with nothing more than dyno results, we must remain skeptical.

From all I have read from numerous people who post here I see that people have had good success in improving drivability and power replacing their old stock one barrel with a two barrel and adapter.

Why is it some people think the only way to get their point across, is to respond with name calling and/or personal insults. Personally I’m getting fed up with it. I have better things to do than to sit here and constantly edit topics in an effort to keep the peace. Every member is entitled to their own thoughts and opinions, even if no one else agrees with them. To those who think their views are the only ones that count, and/or don't know how to respond within the forum regulations, BEWARE. Take that as a fair WARNING…… Instead of locking a topic, which is unfair to the rest of us, I'll suspend or revoke any member that continues to cause trouble.

wsa111":3blupe3y said:

Bort 62 wrote

Jon @ Pony's lack of understanding of the subject is understandable

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My interpretation from what Jon stated, was he does not believe in adapters, since they screw up the air fuel mixture & proper atomization of fuel. He feels its nothing but aggrivation & wasted time on the phone to baby sit novices who do this. I don't blame him at all.

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That is precisely why he didn't like selling 2V carbs for use on a six. In most cases, the carbs need to be rejetted and possibly the powervalve. While some guys know how to go about tuning a carb, many more novice DIY mechanics do not. The first thing they do is pick up the phone, call Pony Carbs, and start bitching. Hence, it was only a nuisance as far as he was concerned.

Like many others, Jon has never seen the six as a performance motor. Ford did a great job convincing everyone it wasn't, and promoted it as an economical and reliable grocery getter. Therefore he, like many others, thought it was silly to put a 2V on a six, as well as a waste of money. I think some of us forget the rest of the V8 world still thinks its a waste of money. How many times have we all been told to ditch the six?

However we did a pretty good job showing him that a six can make power, even equal to that of a SBF, and still get good fuel mileage. Since then, they have changed their policy and have started selling 2V carbs to inliners. He's just hoping it doesn't lead to a ton of phone calls and complaints. Can't say I blame him for that.

As for the new Vaporizer, we just need to give it some time. I'm quite sure we'll hear a lot of stories about them in the next few months, some from our own members. Personally I think its going to be nothing but good, but that's just my opinion.

I promised a follow up report on modifications to a carburetor either above the venturi & also below.
I called several carb shops & found on a 390 cfm holley 4 barrel carb if you just thin the throttle shafts & install button head fasteners for the throttle blades that you gain about 40 CFM in air flow.
So that is roughly a 10% gain in air flow without touching the venturi.
There are many things such as booster size in the venturi which can have a major impact on flow through the venturi.
In closing it appears my statements were as right on, & i just wanted to prove it.

Mike, if i was running close to a stock engine i would purchase the vaporizer in a heart beat.

On these small engines the annular discharge boosters are far superior to the down-leg booster.

If you had a 350" plus engine the annular boosters would produce more low end power but would possibly hurt top end power & because of too much booster signal would go too rich at the top end even beyond the control of the fuel air bleed. Bill

wsa111":3i4kv4wm said:

I

I called several carb shops & found on a 390 cfm holley 4 barrel carb if you just thin the throttle shafts & install button head fasteners for the throttle blades that you gain about 40 CFM in air flow.
So that is roughly a 10% gain in air flow without touching the venturi.
There are many things such as booster size in the venturi which can have a major impact on flow through the venturi.
In closing it appears my statements were as right on, & i just wanted to prove it.

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Bill,

I think that statement shows a lack of understanding about how this all works that is fairly fundamental to your original assertion.

Something projecting into the flow path, like a throttle plate (or booster) will impede flow regardless of the size of orifices involved. Yes, you can improve the flow through a carburetor by reducing obstructions in the free field, like the throttle shaft.

That doesn't mean that the venturi is still not the limiting factor. The are two independent parts, working in conjunction. Putting your hand across the inlet to your carb will impede flow as well, but this has nothing to do with the venturi.

At this point, no amount of arguing back and forth is going to convince you that I am right, that much is clear. I think I've made a pretty clear argument that has been supported by plenty of others, as well as plenty of empirical evidence.

We are going to have to agree to disagree on this one. I'm not going to continue to berate the point.

Corvette people argue about which floormat is best: Lloyds or genuine GM.

FordSix people argue about which carb is best.

In every forum, there's going to be one topic that causes more rancor than anything. And we're seeing it first-hand...

Relax and be happy, folks! 8)

Ian, thanks for the reply.
I assure you there is no misunderstanding here.

There are too many X-factors in an automotive engines induction system that you can use a simple equation to predict the exact results.

Like you stated we will never be in aggrement.

In your world you deal with a set design, unless its computer controlled to deal with variables.

I respect your input from your training.

I work in the automotive field & have for many years after college & have worked on induction systems from carters, rochesters to holleys & autolites & even corvette fuel injection systems.

I don't care what others have said, for instance David CZLN6, on that perticular instance the throttle plate diameter is sufficient to handle both venturi diameters sufficiently. That will not always be the case.


With todays technology via an innovate wideband air fuel tester i can now tune a fuel curve from the drivers seat. Years ago it was a trial & error deal.

Nuff said, end of conversation & posts. Bill

Benchracing at it's best. I have a bench so I will jump in.

As I see it, a 1.75 hole will out flow the smaller venturis. However, if you force both venturis to curve together, while trying to negotiate around the butterflies and square edges of the bottom of the carb baseplate, It will flow less than it would on a direct mount setup. This will be less than optimum. If you could make the adapter about six inches tall, you might not have much restriction. If you make it short enough to fit under the hood, there will be some restriction.

If you visualise a 2V carb on an adapter and think of the turbulence from everything involved, you will see that while you can get an improvement from an adapter on a budget, you should do it right and direct mount it.
I believe in having to do it for an improvement, but if I had the head off, I would direct mount.

Has anyone considered wet flow? After the airflow pass thru the venturi, it has fuel and the fuel must also negotiate these turbulent times. How does dry flow in the venturies compare with wet flow thru the adapter/hole?

The turbulence can actualy help with low speed drivability. I can restrict at high velocities.

Unless someone is going to get on a flow bench and follow up with a dyno. it is pointles to argue.

Bill has a very informative tool. I am getting some great info in the real world from my LM1. I am fixing to install the AUX box on mine and then I can get some more real world data.

Sorry guys, the clutch on my bench is slipping. After I get my clutch fixed, I will re enter the race. 8)

Gene currently has a stock log head and carb on his motor. We've been talking about putting it on a chassis dyno and doing a couple baseline pulls. Then install a Hollley 350/500, and a couple Autolites, via an adaptor and doing a couple more pulls. I'd really like to test a progressive Weber too, but I can't see spending the money for a carb and adaptor just to do a couple runs. I guess I could sell them as used afterwards, or see if anyone has one they would loan for the test.

Gene already has the modified head all set up and ready to go. But before he does the head swap, I could take it to my porter and have it tested on the flow bench. We could also test the log head after its yanked off the motor, with both the 1V and a 2V via an adaptor.

Once the head swap is completed, I'd like to make another trip to Pony Carbs. Not only would we gain some valuable information, it would also be a great opportunity to show Jon what can be done with a direct mount carb and to see which Autolite carb worked best. Not only is the dyno time free, their experience would be a big help. Of course, we'd test both Autolite and Holley carbs so we don't offend anyone.

While it may not be a prefect enviroment, at least we'd have some numbers to compare, which is more than we have now. What I'd eventually like to do, is to put a dollar amount per HP gained for the different modifications. Such as carb swaps, ignition upgrades, headers, cams, and high ratio rockers; both singular and in various combinations.

PS: I'm really pleased to see everyone agreeing, that its OK to disagree. Not only can it be fun, if everyone is civil, we can all learn a great deal from such topics. Thanks guys.......

AzCoupe":15niac95 said:

Gene currently has a stock log head and carb on his motor. We've been talking about putting it on a chassis dyno and doing a couple baseline pulls. Then install a Hollley 350/500, and a couple Autolites, via an adaptor and doing a couple more pulls. I'd really like to test a progressive Weber too, but I can't see spending the money for a carb and adaptor just to do a couple runs. I guess I could sell them as used afterwards, or see if anyone has one they would loan for the test.

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Awesome Mike. It would be great to see:

1.) How much power was made "stock"/
2.) How much power could be made w/ various carbs on a 2bbl adapter
3.) How much power can be made w/ a direct mount 2bbl.

I'll put my money down that they go in order, with the 2bbl adapter making more power than stock, but less than direct mount.

Pulling from my above statements:

Bort62":15niac95 said:

I don't think anyone is going to argue that a 2 into 1 2bbl adapter is as good or better than a direct mount...The question, however, is whether or not the 2 into 1 adapter w/ a 2bbl can be any better than a 1bbl alone.

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