Pony Carbs in Mustang Times

Mike, Jon Enyeart had a very nice article in this months issue of mustang times on the renewed interest in six cylinder cars & performance.
So far they have orders & sold over 200 "Vaporizer" carbs.
In may, Mike Winterboer from classic inlines came to our facility to do some dyno testing with his new aliminium head. We tested several types and sizes of carburetors with this head.With our spreadbore 4100 carburetor we were able to make over 200 hp at the rear wheels. The autolite 2100 blew away the holley 2 barrel that was on the car when we pulled it into our shop. Until this head was available, we NEVER recommended putting anything other than the autolite 1100 one barrel on a six cylinder. If you want more informantion on these tests or the new head available by Classic Inlines. Visit www.classicinlines.com/PCdyno.asp
Mike, i think Jon is now a believer. Wait till he sees a modified log.
Obviously not as much power but will out perform the one barrel carb. Bill

Bill,

I have been working for the last 8 months with Jon on my engine and a carb issue. He originally spec'd out the 1100 for my hot six..(I had sent him all the specs), It wasnt until last month that I was able to convince him to jump up to the 1101 ( a bore match to my 72 head). No instead of spraying gas everywhere..I can actually start the car and get it to run.

I too am waiting for the modified log tests. I believe the 2100 is the better carb, but Jon had refused to sell me one...maybe after the tests I can get him to lean our way. The 1101 is just barely keeping my car going, just enough to drive, but it will stall out after 10 mins. I am just patients and hope he keeps learning like the rest of us.

Jim

Except that he still thinks it is pointless to put anything other than the stock 1 barrel on a 200 with the log head. He is only sold on it if it has the aluminum head.

Don't get me wrong, I am stoked about the CI aluminum head and plan to get one eventually (when the rest of the car is done and can replenish my funds), but I still think he is flat wrong about 2 bbl carbs on a log head...

I just spoke with him yesterday, and that pollicy no longer applies. When we went down there and did the dyno test, I had a lot of time to talk with him. We had several good conversations over lunch and dinner every day we were there. He finally see's the light and is now willing to work with us. Once we go down and test a modified log, I think your going to see a totally different attitude. He's stubborn, but willing to change if you can prove your point to him, which we are in the process of doing. He's even agreed to make a custom carb based on the results of the dyno's. Who else is going to do that?

The problem many folks have is that their intuition tells them that "you cannot cram 2 bbl worth of air into 1 bbl openning". I suspect Pony Carb suffered from that belief too.
But when you think about it, the air flow around a partially closed throttle is no where near the flow capacity of the carb. During 90% of your driving, the plates are not even open 50% .
Doug

66 Fastback":316octei said:

The problem many folks have is that their intuition tells them that "you cannot cram 2 bbl worth of air into 1 bbl openning". I suspect Pony Carb suffered from that belief too.
But when you think about it, the air flow around a partially closed throttle is no where near the flow capacity of the carb. During 90% of your driving, the plates are not even open 50% .
Doug

Click to expand...

In addition to this (and, IMO, more to the point)

A 2bbl carb w/ 1.00" venturis has a cross sectional flow area of 1.57 square inches.

The 1.75" opening in the later logs has a cross sectional flow area of 2.40 square inches.

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.

Ian, i totally disagree with you. I believe the throttle bore diameter is 1.562 on a 1.08 carb.
I come up with 3.83 square inches of throttle bore area that you are trying to stuff into a 2.40" area. That dog doesn't hunt. that is why adapters do not do the job.
To get the full benifit of the 2 bbl it has to be mounted on a direct log mount. Bill

wsa111":406ohr0p said:

Ian, i totally disagree with you. I believe the throttle bore diameter is 1.562 on a 1.08 carb.
I come up with 3.83 square inches of throttle bore area that you are trying to stuff into a 2.40" area. That dog doesn't hunt. that is why adapters do not do the job.
To get the full benifit of the 2 bbl it has to be mounted on a direct log mount. Bill

Click to expand...

Well, I do not have one in front of me - but the throttle bore is not the pertinent #, the venturi diameter is. It is the smallest diameter in the flow path, so to speak - as such it is the primary restriction.

Am I wrong in assuming a 1.08 Autolite 2bbl has a 1.08" diameter Venturi?

Now, if I've got my #'s wrong then that changes everything.

Actually with a 1.08" diameter, I come up with 0.916 sq in per bbl or 1.83 sq in total. So that would not even be as much cross section as large as the 1.75" dia hole.

When you use a Weber progressive carb, then you really are not over carbed. You probably aren't posting much horsepower gain either. But the drivability and response is better. I like to think of it as splitting the flow demands between two bbls rather than relying on one bbl and its different circuits to handle the entire range.

Does anyone know if 1 bbl and 2 bbl carbs are flow rated at the same level of depression? For instance, I know the 4 bbl and 2 bbl's are rated at different pressure ratings.
Doug

66 Fastback":3w2ivayb said:

Does anyone know if 1 bbl and 2 bbl carbs are flow rated at the same level of depression? For instance, I know the 4 bbl and 2 bbl's are rated at different pressure ratings.
Doug

Click to expand...

I gather that 1 and 2 barrel carbs are rated at the same level of depression, yes.

66 Fastback":192gqikl said:

Actually with a 1.08" diameter, I come up with 0.916 sq in per bbl or 1.83 sq in total. So that would not even be as much cross section as large as the 1.75" dia hole.

Click to expand...

Yeah, I rounded to 1.00 for calculations sake.

Guys, this is not a nascar restrictor race.
Have you ever seen a performance manifold with the bores the size of the venturi & not the throttle body diameter??
Heck no.
Do you believe just the venturi diameter as the major flow parameter. Bill

Jammer":27a9fvee said:

Bill,

I have been working for the last 8 months with Jon on my engine and a carb issue. He originally spec'd out the 1100 for my hot six..(I had sent him all the specs)...Jim

Click to expand...

Jim (Jammer),

I thought I read in another post that you were 'beta' testing a Vaporizer 1100. I'm curious what you believe the problems with your 1100 from Pony Carbs was/is (eg prototype issues, cutomization issues, etc)?

Could you elaborate more as to whether or not you had problems with the annular discharge?

-Robert

Here is an informative reference I found on annular, downleg, dogleg, etc.

http://www.popularhotrodding.com/tech/0 ... index.html

-Robert

wsa111":w5bxj79h said:

Guys, this is not a nascar restrictor race.
Have you ever seen a performance manifold with the bores the size of the venturi & not the throttle body diameter??
Heck no.
Do you believe in just the venturi diameter as the major flow parameter. Bill

Click to expand...

Bill,

Funny how on one hand, you claim that you cannot "cram" two 1.5 holes (~3.5 in sq) of flow through the single 1.75 (2.4 in sq) yet on the other you don't seem to think there is any problem "cramming" two 1.5" holes trough two 1.08" venturis?

Which is it? You can't have it both ways.

The total restriction of a system is very much dominated by the highest restriction zone, providing is substantially more restrictive than the rest. (Which a 1.08" venturi certainly is compared to a 1.5" throttle bore).

But heck, I'm only a mechanical engineer w/ experience modeling plumbing systems to minimize pressure drop. What would I know about CV, flow, and restriction?

I suggest anyone interested start here: http://en.wikipedia.org/wiki/Flow_coefficient

Bill,
I am not arguing that the 2 into 1 adaptor is the performance equivalent of a direct mount set up. But the majority of us have used an adapter because it is easier and there are performance benefits to be had when placing the 2 bbl onto the stock engine. They aren't going to be the same magnitude of performance benefits that you have chosen to chase with the modified log, cam, carb headers etc. There is no question, if you want maximum HP and performance, then the 2 into 1 adaptor is not the way to go.

My argument is that some people just tend to focus on WOT and can't get past the notion that a you really aren't cramming 2 bbls into a 1 bbl hole because we don't run at WOT on our daily commute.
Doug

Ian you make a great point. As far s the restrictor plates go, it is a way for the governing body to ensure uniformity by placing an equal restriction across everyone's engine. They could easily restric the venturi size and acheive similar results. But we all know that the crew cheifs would find some way of recontouring the venturi so that it was not the same from team to team. It is pretty hard to measure all the points along a venturi. It is much easier to hand each team a restrictor plate of known and measurable dimensions.
Doug

ok, lets play nice. why is it that every thread involving pony carbs gets everyone up in arms, and ends up being locked?

im not debating the merits of anyones oppinion based on past credentials, but Ian's seems to make more sense. if you can only fit a certain amount of air through a 1.08" hole, then it won't matter how big it is afterwards, it can't pull more ait than the 1.08" hole will allow. this is most likely over-simplified, but thats the concept.

when you change out the venturi on a carburetor (assuming it has removable venturis), it changes the flow rating (CFM) even though the throttle plate stays the same diameter, right? this leads me to believe the venturi has a greater effect on the flow of a carburetor than the throttle plate diameter, and should used in the calculations.

Wow dude, really? Sorry if I disagree with your assessment.

I don't really care what your profile says or doesn't, I think you are wrong - and I have some pretty good reasons why (you're own argument conflicts itself, which is typically a pretty good start).

Edited my own post so as not to come off as insulting...

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